Lucifer’s Hammer, Part 14
The continuing saga on fuel delivery and other more or less routine chores.
7/23/07
Pump shutdown problem showed up again. This near the summit of Independence Pass. My route included I-70 to the tunnels and the top of Vail Pass, Colo 91 over Fremont Pass, some congestion in Leadville, and some traffic from Twin Lakes to the summit switchbacks. This meant running at lower RPM, so possibly less fuel circulating thru the pumps resulting in heat buildup in the fuel (?) The shutdown occurred with air temps around 80 F and about 11500 ft elevation. Until pump shutdown, no fuel flow or throttle response problems had appeared. After ~45rmin with the pumps not operating (or at least making no buzzing) pumps began operating again and I was able to get the engine to catch. Drove down to Buena Vista/Johnson’s Corner, ~45 miles. Run from Independence to Johnson’s is mostly downgrade. RPM held to ~2600-3000, very light throttle without issue. Filled w/ 91 octane. Tank at time of pump shutdown was around 1/3 full–took 11.3 gallons. Subsequent drive back to Castle Rock was Trout Creek Pass FairplayKenosha Pass285 to C-470. Heavy traffic, so light throttle. No problems noted.
Noted later (8/2 meeting w/ Justin): Running at low RPM but under load, e.g., pulling up steep grades @ low speed, warm ambient air temps, high altitude, may result in the secondary injectors barely functioning due to low demand. The fuel then “pools” in the secondary rail and thus picking up heat via the engine block, turbine and especially the radiator. Low speeds = less air flow = more residual heat. This would heat the fuel being returned to the tank, potentially closer to its vaporization point. Having less fuel in the tank would amplify the problem. In all three cases the “vapor lock” problem has showed up with fuel at ½ tank or less remaining.
I think the problem is related to heat buildup in the pumps related to sustained use and heat buildup in the fuel; these factors creating the vaporization and loss of liquid flow to the pump proper. Worth noting, when I had the pump shutdown/vapor lock on Independence, fuel pressure gauge was showing ~10 psi, even with trying to get the pumps to turn over.
One thing that bothers me about all this is that other than the Loveland Pass problem (Aug ‘05), I had gone ~3000+ miles without an issue related to the fuel pumps. This included driving in some fairly warm weather–east of Greeley in late Aug ‘05, I-70 to GJ in May of ‘06, numerous short trips on I-25 in heavy traffic–all without incident.
7/26/07
Discussed problem w/ Justin. He thinks we need to move the pumps to an in-tank location. He assures me there is no potential fire hazard from the pumps used in an immersion environment; Aeromotive’s web page states that pumps can be used in-tank if proper wiring precautions are taken. This would (1) eliminate any potential cavitation issues due to the pumps currently being above the tank, and (2) further cool the pumps by having them immersed in the fuel [heat sink]. Justin has an idea of putting an LED in the pump power circuit which would indicate pump is operating. Not sure what this would provide, other than a backup to not hearing the pump’s growling.
Note to self: I want to get the car up on the lift and run a multimeter on the pumps. The somewhat quieter sound recently makes me wonder if one of the pumps may be in intermittent failure mode.
My concerns:
1. Potential fire hazard with the in-tank arrangement. We need to discuss this in detail with the tech people at Aeromotive as to feasibility.
2. Creating a layout where the pumps are readily accessible thru a top portal.
3. Proper sealing of the fuel filler spout components via a gasket under a surrounding flat plate. The appearance needs to be 100% stock, as the filler spout/cap has to pass the visual inspection at emissions.
8/2/07
Installed an LED alongside of the A/F meter. This in series with the primary pump. Its purpose is to be on when the pumps are on. If the pumps stop operating and the light is off, it will indicate the pump shutdown is due to an electrical fault. If the pumps shut down and the light remains on, the problem is (most likely) vapor lock. One interim possibility to go along with the LED is to put a tee at the fuel pressure gauge fitting on the fuel regulator and run an additional fuel pressure gauge back to where it can be mounted on the windshield wiper and observed when the car is running.
The electrical problem can most likely be resolved by using a bypass jumper connecting the PMP and BAT wires on the primary controller. This also bypasses the controller. The jumper must be removed when the engine is shut off, or it will drain the battery. If the jumper doesn’t restart the pump, we have a problem upstream–possibly in the ignition circuitry.
The vapor lock situation should resolve itself in ~½ hour or thereabouts as the fuel lines cool sufficiently to allow the fuel to recondense. To date, in the three incidents of pump failure/vapor lock, this approach has worked satisfactorily.
Michelin PS2s ordered; the Pneumants that came with the rims from Duke are just about shot. 235/45-17F, 255/40-17 R. Once mounted, will need to do a front end alignment. I want to set alignment at stock specs and see how things go.
8/8/07
Fresh rubber on the car; 136,187 miles. Dave S. out of town thru 8/15, so will get the thing in late next week for a look-see on the alignment and the fuel pumps issue.
8/17/07
Alignment. Replaced tie rods, ends, center link, along with the alignment. Idler arm, center and outer tie rods all exhibiting some play. In any case, the alignment was set to the former values: Camber: -.9, Caster: 7.0, Toe: .08. Details on alignment sheet in records folder. As it is, handling and steering response are quiet, precise and show no drama.
Replaced the fuel pump relay and ran checkover on wiring. No issues as to connections, grounding, etc. at the controllers or the pumps. Keeping a spare fuel pump relay on hand in the car; I will drive the car and keep Dave and Justin advised on any issues.
8/21/07
Ray Avena in C Spgs. has advertised his Alpina 40 liter aux. tank and 70 liter euro main tank for sale. Will have a look this weekend.
8/25/07
Picked up the tanks from Ray. Both in fairly good shape. Ray sez they both have been pressure tested by a radiator shop and got a clean bill of health. There is one marked spot near the filler neck on the aux tank which shows the faintest trace of rust around the weld bead. This may need to be re-heliarced out of an abundance of caution. The main tank appears to be in good shape; no rust around the vent piping (a frequent rust/corrosion problem area). Per Duke’s suggestion, I have looked at the small-diameter vent tubes where they meet the main tank for any evidence of corrosion. Given that the area is still painted, I’m not seeing anything.
Aux tank trial-fitted. Can’t go all the way in, as the front locating pins are present and I didn’t pull the trunk bulkhead carpeting. Duke’s photos of his tank installation show location holes with grommets; installation will mean cutting holes in the bulkhead carpet. The fit is very close, but good. The only issue I’m seeing at this point is the aux tank is right on top of the fuel pump and controller wiring on the passenger’s side wheel well. Prudence, to me, says see if the tank can be trimmed to provide space around the wiring. Doing this will mean cutting and re-heliarcing in an aluminum end plate on the tank, or finding a way to shield and insulate the wires.
The aux tank has/had remains of 2-sided tape on the aluminum, along with three 1/4" neoprene foam strips on the bottom. These are for sound and vibration insulation where the tank rests on the trunk undercarpet padding. The tape and foam has been removed in order to expedite the cleaning and powdercoat prep. steps. The plan here is to have both tanks media blasted to bare metal in order to allow a close inspection for any corrosion, damage or rust prior to powdercoating.
The main tank will need to have a bulkhead fitting brazed or welded into place to accept the fuel return line prior to being powdercoated.
Again per Duke, the filler necks will need a 1½" ID piece of fuel filler hose to connect the tanks. Duke says this came from a Jeep, but he doesn’t remember what model or year.
Ray suggested that the in-tank fuel pump frame from an E21 320i is a drop-in for the euro fuel tank. I will need to see if the present setup on my tank will fit as well, Justin having modified it for the pickups for the A-1000 fuel pumps.
I hope so, as the 320i frame is about $250, and I need to be able to use the current fuel float level unit–don’t know if it is compatible with the 320i frame. If I have to use my present frame, it may prove necessary to modify the tank opening. We will have to have things out of there to see what’s going to be required.
8/28/07
Aux tank has been trimmed, end plate welded in, pressure tested OK. Aux and main tanks are at Blast-Tech being prepped for powdercoating. One potential hurdle is that fitting the pumps is going to mean opening up a fairly large portal on the top of the tank for access, then working out a way to reseal the opening. This will be around 6" x 8" so not a trivial matter. Derick at Spike Radiator (who will be doing the internal cleaning of the tank–fair amount of accumulated varnish, rust, mung, etc. in there--) tells me that they will have to open up a portal anyway in order to do the interior cleaning. This gets soldered shut when they are done. Once stripped, set up time @ BH to work on test-fitting of tanks, location of bulkhead fuel fittings, fuel sender opening exercise.
I am going to have to design a few things for this setup:
1. A locating plate for the pumps to be attached to at the bottom of the float level frame. This will have to be resting against the bottom of the tank, but also vibration-shielded.
2. Locating the fuel pickups both close to the pumps and where they are protected from fuel sloshing at low tank levels and/or various accelerations.
3. Reworking the fuel lines from pump outlet thru the fuel float frame and thence to the feed lines going forward to the rails.
This is going to be a fair amount of work. Installing the fuel return bulkhead fittings shouldn't be too bad (I hope).
In looking at the A-1000 pumps themselves, they are each about the size of a Foster's beer can. With these going in-tank, there will be a loss of about a gallon of capacity in the main tank, so adding the auxiliary tank has become more of a necessity.
8/30/07
Picked up the 1/2" neoprene foam for the bottom of the tank spacing/insulation and the 1/8" fuel-resistant neoprene gasket rubber from Mike Moon at Rubber, Inc.
10/6/07
Over the past 5 weeks or so, a fair amount of progress has been made, along with a number of delays.
Deal with the delays first. Getting the welding done on the tank is proving to be difficult. Mike Butcher at MPB Alumafab is one of the few people willing to work on a fuel tank–nevermind that the tank is bone-dry and has a foot-square opening in it. I suspect most weld shops have worries about potential liability.
Points to consider:
1. The tank appears to have galvanized in manufacture, so surfaces subject to welding or brazing will need to be ground clean to assure solid welds. Some of the potential weld areas still have evidence of rust, etc., so added attention is called for in preparation.
2 .The quality of the work has to be perfect in order to assure the welds are airtight, and despite careful cutting on the portal opening, there are gaps up to 1/8” wide between the reinforcing perimeter plate and the tank body which will need to be filled with bead. My cutting with the sawzall wasn't exactly neurosurgeon quality . . .
3. There are significant differences in material thickness between the reinforcing plates (3/16", 1/4") and the tank sheet metal (1/16") which make keeping things straight and properly aligned during welding difficult. This is doubly important for the pump mounting, where the fitting on the tapped holes is very tight.
4. Attaching the fuel pump sender reinforcing plate to the interior of the tank will be somewhat delicate, as it has to be TIGed to the upper body of the tank, but without affecting the six securing bolts (currently dummies) for the top plate.
5. The prior work (brazing) is poor, and realigning the aux tank filler neck and breather tubes is made considerably more complicated by both the workmanship and the dissimilar metals.
All this means this is a job that can’t be thrown together.
Add to this the scheduling issues at Alumafab–Mike is buried with several major jobs, so smaller ones such as mine have been pushed back. Had things gone quicker at BH and the tank put in his hands in early Sept, things would be different. Tank was dropped off 9/25; Mike thought it would be at least a couple of weeks before he could get to it; this was before these large $ additional jobs came in.
The scheduling--- MPB–>test fitting–>possible additional welding–>tank internal cleaning @ Spike–> (plus concurrent beadblasting heatshields and access plate @ Blast--Tech) –>powdercoating @ Premier –> internal coating @ Spike pushes things out on completion. This has created some tensions @ Bimmmerhaus as the car is occupying floor or rack space. I have had a conversation w/ Bob T. on the matter and outlined the issues. He understands that the delays are not voluntary, and will work with me, I think, on trying to keep matters moving forward expeditiously.
As to items in the work flow.
1. The access portal has been cut–the opening is about a foot square to allow both pump installation along with the internal fuel lines and reinforcing ribs. The portal has a surrounding reinforcing plate of 3/16" x 1 ½" steel strap. This does several things. First, it provides protection for the small-diameter breather lines inside the tank. These got exposed to potential damage when the portal was cut. Second, cutting the portal significantly reduced the tank’s stiffness. Third, it provides some measure of protection from injury while working inside the tank–the tank body is made of 1 mm steel, and even with cleanup around the edges, there is a real risk of getting cut. Fourth, the “ring” provides a securing area for the numerous bolts holding the access cover plate and its underlying gasket in place.
2. The fuel feed and return bulkhead fittings have been located and the tank drilled for their mounting.
Refer to "Bulkhead fittings welded in" photo.
Feed line connections to the pumps are by -8 Aeroquip braided steel flex hose. The internal fuel return line is fabricated from 3/4" OD soft copper tubing, and empties near the back of the tank.
3. The pumps are mounted longitudinally, roughly in the center of the bottom of the tank–this being about the only feasible space; the surge pot taking up the front third of the tank floor, and the aft third angling upward. The primary pump, on the passenger side, has the pickup located in the surge pot and feeds the primary thru a ½" OD soft copper tube. The outlet faces aft, feeding the bulkhead fitting thru about 15" or so of flex hose. The secondary pump is reversed, i.e., the pickup is at the back of the tank, the outlet being about 7" from the front bulkhead fitting. Fuel pickup for the secondary is thru a -8 AN 90 elbow which has the opening about 1/4" off the floor of the tank and right where the tank floor begins to angle upward.
4. Both pumps are secured by safety-wired AN4 bolts to ¼" x 2" steel reinforcing ribs welded into the bottom of the tank. These ribs both support the pumps and provide sufficient depth for purchase of the pump mounting bolts. While the pump’s functioning in-tank hasn’t been tested yet, there is a genuine concern about vibration and transmitted noise during operation. The safety-wiring and use of wave washers on the bolts should remove the possibility of the bolts working their way loose, but I have been unable to locate any kind of vibration-isolating bushing where the elastomer will survive indefinitely in a gasoline environment.
[replacing the pump mounts on a scheduled basis would be a fairly major undertaking–requiring complete disassembly of the fuel storage system.]
5. Power and grounding for the pumps will go through a 3/4" ID stainless steel ell welded into the fuel float sender plate. This fitting replaces the former -8 elbow used for the feed to the primary pump when it was located outside of the tank. The wires will be “potted” in the ell with 890B aircraft epoxy. This stuff has very high resistance to the effects of fuel and (so I am told), does not become brittle with curing. The exterior end of the ell will also get a plug of RTV silicone which should also bond to the vinyl insulation on the 10 gauge plug wiring.
6. The in-tank reinforcing plate for the fuel float sender frame has been removed from the original tank.
The euro tank sender was secured via an interrupted thread arrangement and had a stamped metal “guard” to locate the gasket. The one from the M5 is a steel ring roughly 5 mm thick, tapped for six securing bolts and was spot-welded into position. This has been TIG-welded to the inside of the euro tank to locate the external plate for the fuel float sender; this external plate also holds the pump wiring port mentioned in #5, above.
7. Test-fitting of the euro tank identified several problems.
A. The alignment of the aux tank-to-main filler neck tubing needs reworking. The elbow on the euro main tank is misaligned by over an inch (18 deg. off), and so will have to be aligned and rebrazed. Parenthetically, the brazing on this elbow and the extended filler neck is very poor workmanship and needs to be redone.
B. The breather hose fitting on the aux tank is 9/16" OD and will not accept the -8 Aeroquip hose used for the breather line, so this stub will need to be trimmed off and a piece of ½" OD aluminum tube ~1 ½" long TIG’ed in to replace it.
C. The extended filler neck is very close to the top of the fuel filler box– there is barely room to remove the gas cap; in order to close the cover door, the plastic holder for the gas cap had to be removed. The proximity of the top of the filler neck to the fender makes it questionable whether a gas filler spout could reach into the neck, let alone put the nozzle thru the constrictor door which is 3" or so into the neck. It might be possible to use a funnel to open the constrictor door @ each fill-up, but the solution points to the need to shorten the filler neck extension by at least an inch.
Doing this may also provide sufficient clearance for the cap holder on the filler box door.
D. Concurrently, the connecting pipe for the aux tank breather hose has several potential problems:
One, this pipe on the filler neck is 3/4" OD, and so will not work with the -8 Aeroquip hose. Thus this will need to be removed and a tube ½" OD x 1"-2" long substituted.
Two, the present location of the stub places it nearly on top of one of the three small-diameter breather lines coming from the tank. Shortening the filler neck extension may solve this problem.
Three, the proposed location for the aux tank breather hose runs the line very close to the bottom of the filler box. Drilling thru the filler box itself doesn’t appear to create any problems, but the location is very close to some frame structural members, which do not need to be cut.
Four, the contemplated stub location is (I think), below the level of the top of the aux tank, so there may be a fuel/air flow problem when filling the tank–effectively creating a siphon in the breather line.
Worth noting is the photos Duke has of the breather line installation in his M535iT show the breather hose just below the gas filler cap. This put the breather well out of the way of the three small breather hoses which go to the in-trunk evaporative capture box. FWIW, Duke told me there is no restrictor plate in his filler neck; this makes sense as the restrictor plate is a US EPA/DOT requirement, and his tank was strictly a European proposition.
I don’t have a problem with relocating the breather hose stub to Duke’s location, but I certainly don’t want to run afoul of any issues which might arise during an emissions/safety inspection for plates. I am aware of the pressure test that is done on the gas cap; I believe the emissions nazis also use a plug gauge to test the restrictor door, so I don’t want to give them any cause to look further.
With the tank welding done, the only way to confirm all this will be with a test-fitting and see what we’ve got for clearances before doing any metal-cutting.
8. The in-tank pump location means that the use of a pre-pump 100-micron filter isn’t feasible, both from a space and replacement access perspective. This means a number of things.
A. All metalworking on the tank will need to be done prior to the tank boilout/cleaning. This especially applies to the drilling and tapping for the access plate securing bolts.
B. To reduce potential foreign object contamination to a minimum, the “pickling” of the tank to eliminate the rust, scale, and corrosion now present is essential.
C. This will be followed by urethane coating of the tank interior after the powdercoating has been done. Powdercoating precedes the tank coating as the temperatures in the powdercoating process (~450deg. F) will damage the urethane.
9. The in-tank layout has realigned the fuel hoses between the hard lines leading forward to and from the rails. Both feed lines contain a 10-micron filter, and both still traverse the unibody in the space above the top of the diff housing, but the configuration is simpler, as the pumps have been moved. I don’t think this will affect flow at all, but there are fewer
bends in the hoses. Fuel return is basically identical to the former layout.
The pictures included in the Part 14 addendum (previously posted) are not in any particular sequence, but are for reference in this discussion.
10/18/07
Interior of the tank cleaned @ Spike; filler neck shortened about an inch, breather stub on the filler neck has been relocated to just below the cap closure—this in the interests of hose installation and avoiding the possibility of a “fluid lock” occurring during filling of the aux. tank. Tanks, cover plates and heatshields have been bead-blasted and are at Premier for powdercoating.
10/25/07
Carl has gotten the tank cleaned. Most of what I was worried about--rust, corroded zinc, varnish from fuel left in there--came off during all the internal work over the past month-plus, so the actual cleaning process (media-blast then high-pressure wash with methyl ketone) went fairly easily. The coating is only a couple of thousandths thick, so won’t affect threads on the bulkhead fittings. Pump location bolt holes had dummy bolts in place as a precaution.
In a way it's too bad that the tanks aren't going to be out in view for everybody. The combination of the media blasting and the 40% matte black coating makes them look
quite spectacular.
10/30/07
The urethane has given me the world's one and only candy-apple red gas tank!
What makes this really special is it's the interior. The coating is, according to Carl, just about immortal and impervious to gasoline, alcohol and virtually any other compound I might use as fuel. Ought to prevent anything bad happening in the way of corrosion . . . .Tying in the pumps took a bit of doing. The mounting bolts locations are hard to reach; getting them into place with requisite lockwashers then putting in the safety wires required hands several sizes smaller than mine. That being done, the braided hoses with the Aeroquip ends were tough to do, as they have to line up perfectly with their respective fittings. Clearances in-tank are tight, so I had to hunt down some crowfoot wrenches to get things snugged up.
10/31/07
Wiring went fairly easily. Connections at the pumps themselves wasn't an issue--just not much room. Running everything up thru the trunk floor portal got a bit tight, but ende gut, alles gut, no?
With all the interior stuff done, portals got sealed with 890B. So the thing looks relatively clean--absent the ooze around the edges. Hopefully not too much of the excess 890B got down inside the tank, and what did has stuck to the interior. I am having a big paranoia attack over this, as the stuff sets up to the consistency of bubble gum and it would totally screw the pumps if it gets suctioned into them. That, and opening everything up would be a Royal PITA. Both sides of the neoprene gaskets got a coating of 890B. Hopefully the pumps will run forever because opening this puppy up is going to be a genuine joy
Fitting the tank back into position took a bit of doing; the added 3/8" of height created by the access portal bolts wouldn't let the mounting bolt holes line up properly with the frame, so a bunch of reworking on the mounting holes in the flange of the gas tank. No big deal, but it added a couple of hours to the exercise. Why the height issue would cause this, I dunno; when we did a trial fitup yesterday, the access panel wasn't bolted in, but everything lined up just fine.
11/1/07
Other than that, the installation has gone relatively smoothly, as it should--we have had the various components in and out of the car at least 8 or 9 times each, so we ought to be getting good at this.
Getting the aux-to-main connecting hose installed was anything but easy. Space and clearances are more than a bit tight, and the short length of the hose doesn't allow much maneuvering room.
Taking as much time as I have playing with the exterior fuel feed hoses is paying off, as they are lining up directly with the AN fittings.
No problems with the aux breather hose, given the relocation of the stub in the filler neck.
Partial fill on the tank sez the pumps are working jes' fine. The internal location seems to have muted much of the noise that was present when I had them up in the wheel wells., tho' they still transmit a fair amount of growl when operating. Unfortunately there is no way around this that I'm aware of. I have been unable to come up with any kind of vibration isolator (similar to a trans mount) that will live long-term in a fuel environment without the elastomer giving it up.
So I go to fill the tank(s). Everything is cool, then I notice this . . .puddle . . . about the size of a dinner plate and growing appearing under the car.
Closer inspection shows it is coming from the brazing at the bottom of the aux-to-main filler neck right in front of the sender plate. <<sigh>>. Back to Bimmerhaus. All hands, GQ. We pull the exhaust, disconnect the pump wiring and the breather hoses; 25.7 gallons goes into the Yukon.Note: the 25.7 gallon figure = 97.2 liters. Figure the euro main tank = 70 liters or about 18.5 gallons. The aux tank = 40 liters or about 10.5 gallons. 18.5 +10.5 = 29.0. Subtract about 1.50 gal equivalent volume for the internally mounted pumps and plumbing and I should see 27.5 gal. capacity. Why the difference, I dunno, unless the location (height) of the breather vent isn't letting the aux tank pick up the remaining 1.8 gallons.
In any case, assuming 16.0 mpg and leaving ~5-6 gal in the tank to avoid any issues with pump feeding, I should have a range of around 320 miles or so. If I cool it on long distance cruising, keeping speeds to around 70-75, I think I can bring the mpg # up closer to 20. We shall see.The only drawback I'm seeing on fillup is the tank is slow to accept fuel thru the filler neck. This is because the constrictor is very deep in the pipe and the gas spout won't quite get thru the opening, so the routine looks like dribble it in, or fill, burp and wait a moment.
Drop the tank. With 3 guys on it, the foregoing takes about 15 minutes, max. Screw this. It's late and I have an hour drive to get a reheated dinner.
That, and I get home to find that the market is beating the snot out of a number of our holdings. My 'tude leaves a great deal to be desired, especially so as I am out of alcohol and I need a very stiff drink.
11/2/07
Got a really good look at the source of the leak. Seems that there is a fatigue crack in the body of the tank running laterally between the vertical filler neck and the portal for the fuel sender. The crack is about .750" long, maybe .010" wide. Totally invisible, as it is covered by the powdercoating. Wire-brushed and surface-ground the area clean which was the only way we could find it--the media cleaning left a matte finish which hid the damage, which was further covered up with the powdercoating.
Stepping back for a moment, if I were to fill the main tank to its normal capacity and not use the aux, the chances of seeing the problem aren't really high. The problem showed up when the fuel level went up thru the aux-to-main filler neck, thus creating about a 4"-5" "head" of fuel above the top of the main tank. This supplied the liquid which then took the line of least resistance and seeped thru the fatigue crack. What got really scary about this is the seepage was going along the sides of the tank and onto the exhaust. If I hadn't noticed the puddle under the car at the gas station, and immediately drove the half-mile back to the shop, the probable consequences are fairly ugly.
This leaves me with several unappetizing choices.
1. Tank is drained of fuel, but will need to be totally dry and free of any residual fumes before attempting to end-drill and braze in the crack. Trying to weld over the brazing really won't work, due to metallurgical incompatibilities. If I do braze this thing, there are significant issues with both the powdercoating and urethane--removal and redoing, to say nothing about pulling the pumps and internal wiring and plumbing.
2. Cut out a section to include cracked area and the filler elbow, add in a new elbow and weld in the new piece. This after having urethaned the interior of the tank and powdercoated the exterior. See comments above.
3. Find a new euro tank and repeat all the fab. stuff that was done to accept the pumps, bulkhead fillings, coatings and so on.
4. End-drill the crack and coat the area and a few inches around it with 890B. The 890B is elastic enough to deal with any flexing, and the tank, once reinstalled, shouldn't place any stress on the filler neck.
Oh yeah, it gets better. Seems I beefed it when mixing the 890B batch--while I followed the directions, what I wasn't told is that in Colorado's low relative humidity (~15-20%), the mix requires (a) about 1/3 more accelerant, (b) once mixed, the stuff needs to be misted lightly with water as it is put into place--higher humidity being needed for proper curing, and (c), the compound needs to be kept at around 77 deg. F for the 12-15 hours it takes to cure. Since I didn't do this, the compound was both uncured and incredibly sticky to the touch. Faaaack.
So everything has to come apart and have this . . .mung . . .scraped off and everything washed in Methyl Ethyl Ketone to get back to bare metal..
Anyway, it got done.
We decided to try for plan #4, above, largely out of some kind of time consideration on getting things back together. Mark Hutto, one of the techs at Bimmerhaus is also an A&P mechanic. Mark has some experience with 890B and his assessment was the drill-and-cover approach would probably work, as long as the filler neck isn't used as a stressed member. Upon close examination, the crack isn't something that just happened during the course of the test-fitting that I've done over the past month or so. As I've mentioned in the past, the quality of the brazing on the tank sucks rocks, to put it mildly. So it is anyone's guess what kind of treatment the main tank had to cause the crack in a steel sheet that is about 1 mm thick and (as far as I can tell) shouldn't be a stressed component. So we shall see.
Mark mixed up another batch of the 890B, and drawing on his experience, put in a HUGE amount of the accelerant. Only downsides being the normal 2-hour pot life goes down to something like 15-20 minutes and the smell it gives off is truly astonishing.
But the portal covers are back in place.photo: 890B elastomer epoxy for sealant around fuel sender/ wiring portal.
11/3/07
This was a kind of special day @ BH. Shop is closed on the weekends, but today Dave and Brad (two of the techs) were working on their own iron, so Dave told me to come on in and work on LH.
My results from yesterday evening.
There is still the tiniest of fuel seeps around the fuel level sender. Rather than pull everything back out, the next step will be to build a bead out of JB Weld or somesuch and close off the seam at the sender unit. This is at the base of the elbow with the pump power wires coming out of it. The big shiny area in the picture is the sealed patch to deal with the crack I mentioned earlier--much wider than the damaged area, but I was being careful . . .
The fuel level needs to be below the level of the top of the sender to eliminate any fuel seepage into the leaking area. It also needs to be bone-dry to allow the JB Weld to bond properly.
The seep at the fuel sender is, we think, a result of the weld bead near the wire feed elbow being somewhat uneven even after being ground; the result being the gasket doesn't give a 100% seal, and I didn't gob a whole lot of 890B into this area. This last point was in case I ever have to pull this thing apart. So there is still a bit of work to do, but at least the seep isn't dribbling onto the exhaust.
So the qar got driven home this afternoon, totally without incident. Remaining steps are the epoxy bead, reinstalling the cover plates and the wheel well carpet. I also need to get a pattern for the floor carpeting up to Euro Auto Interiors.
Having sat in the shop for the past two months, it badly needs a bath and rewaxing.
11/07/07
Built up a dam around the wiring elbow and filled things in with JB Weld. Thus far, no leakages after three days. Cover plates reinstalled, carpet template made.
Plan is to take the lump back to KC this weekend and let Samouce and Couvillon have a chance at the thing.
11/9/07
To KC. First really extended trip with this sled. Getting around 21+ mpg at a steady 75 mph cruise. Experiencing some measure of “hiccupping,” with an abrupt fuel cutoff when I go into trailing throttle mode. This is showing up when I’m running 3000-3200 rpm (75-80 mph) on steady loadings. Also noticeable when accelerating from standstill.
11/10/07
Localized driving around the Leavenworth, KS area. Mixed bag of low speed plus some aggressive pulls where appropriate. Boost getting up to around 5-6 psi then BOV is opening up. Keeping boost controller in low setting. Duke and Brad are impressed.
11/11/07
More assorted news.
1. Paul had the opportunity to drive this thing yesterday afternoon. He thinks the A/F ratios are too rich and could be leaned out which should smooth out throttle changes.
2. Talked to Stackhouse. Described the problems on the hiccup. His thoughts: (a) possible vacuum hose has come loose which would explain the idle hunting and poor response coming from a constant throttle setting--regardless of RPM or loading. (c) possible pressure hose has come loose at the wastegate. Game plan is to get it into Bimmerhaus this next week and have a look.
3. Talked to Justin as well. We need to have the car out to see if we can replicate the problems and do datalogging at the same time. NOT a good idea if the roads are snowy.
Justin agrees with Dave's thinking for the most part, and thinks that the deceleration cutoff coding on the TEC may be too sensitive.
There may also need to be some further readjustment on the boost controller settings as well.
The tip-in on throttle got more noticeable over the drive home. The "hiccuping" is especially apparent on decelerating/trailing throttle transitions. Lift my foot and I was getting near-total fuel cutoff, tho' fuel would come back right away when I added throttle again.
Fuel economy coming west was right at 17.0 . . .vs. the 21.7 I got going to KC. This with no appreciable difference in speeds or driving patterns, i.e., steady 70-75 mph in 5th over freeway driving. Coolant temps holding around 180; oil @ 190. EGT temps 1000-1150 or so vs. 920-950 on the trip down.
On a couple of stops where I let the car idle, hunting was noticeable. If I let the car sit at idle for 2-3 minutes, it would stall and die. Restarted readily, but the dying is something new.
11/19/07
Numerous items at the once-over @ BH.
1. Oil change-no issues, other than the oil is dark chocolate in color. This is due (per PB) to running rich and the result is fuel contamination in the oil. No foreign matter seen in the filter.
2. Changeout of 10-micron fuel filters. A few metal particles and some bits of urethane; both from the work on the tank internals. Shouldn’t need to revisit the filters for some time.
3. Several oil pan bolts loose or missing (
!!). Replaced, w/ wave washers added for security. Two of the loose bolts were caught in the lower bell housing cover. No indication of any harm done, but the absent or loose bolts may have contributed to some of the minor oil seepage I had noticed over this past summer.4. Small fuel leak noted at the O-ring on the #1 cylinder primary injector. Not sure if this is due to a defective O-ring, an assembly problem, or fuel reacting with the O-ring material. Solution is to replace all the O-rings with Viton ones, out of an abundance of caution.
5. Inspected the BOV and lines to & from the wastegate. No evidence of any loose hoses, breaks or whatever.
So the remaining items are:
6. Hunting @ idle. If car is allowed to idle for 2-3 min, problem seems to get worse, then the car stalls.
7. Severe fuel cutoff when letting off throttle ~3000-3200 rpm in 5th. Speeds ~75-80 mph. Cutoff is near-instant; severe stumble for 1-2 sec when rolling back into throttle.
Decel and tip-in on throttle aren’t smooth. Problem is also present when coming off-idle and accelerating in lower gears, e.g., coming off of a stoplight.
8. Throttle transitions have become more balky after having done numerous full-throttle acceleration runs with turbo boost going into the 5# range.
9. PB noted smell of fuel in the exhaust. He is of the opinion the car is overall running too rich--soot deposits @ tailpipe, less than ideal throttle response at lower RPM.
10. EGT on trip east ran 900-920; trip home was in the 1000-1100 deg. F range. Oil temps consistently around 190deg thruout trip. Coolant ~175-180deg.
Possibilities:
TPS going bad
vacuum leak(s)
boost line loose from wastegate, BOV or plenum
bad spring in wastegate?
boost controllers worked their way out of adjustment.
bad spark plug–noted some discoloration on porcelain insulator when doing valve adj/leakdown this past spring.
Deceleration fuel cutoff settings too sensitive or abrupt in the TEC-3r BIN file or in the firmware
12/14/07
Followups from the 19 Nov. work. Paul has sent a set of Viton O-rings for the injectors. (See item # 4, above.) Both injector rails pulled, all 24 O-rings replaced. This seems to have (a) stopped the leak under pressure at #1 primary injector, and (b) stopped the flickering seen in the fuel pressure gauge. As regards this point, I had noticed the press gauge needle was flickering rapidly over a 4-5# range at idle, where the pressure s/b stable at ~42-43 psi.
In the course of removing the intake plenum to do the rails, we noticed that one of the two breather hoses leading from the top of the intake plenum was open to the atmosphere. The other hose feeds into the Intake Air Control (IAC) valve. Other fittings on the intake plenum–MAP sensor, MAT sensor-- appear to be tight. Also noted is the interior of the intake plenum shows no traces whatsoever of any oil. This is a good thing. Back to the open breather hose. A polyethylene hose cap(?) slightly larger than the breather hose ID was found resting on the LH side frame rail. The open hose was then plugged with a copper pipe cap and secured with a hose clamp.
Over the past month, no oil drips onto the floor have been seen, so the pan bolt reinstallation may have solved the issue, but will need to reinspect in the spring.
With the breather hose secured, everything buttoned up. Car restarted without issue. To be noted, with reference to the above enumerated items:
# 6. Idle has smoothed out noticeably, with minimal hunting.
The other items, 7 thru 10 inclusive, were not able to be evaluated, as poor road conditions (frozen, snow) meant serious road testing could not be done. On one brief stretch the throttle was taken into boost, around 2-3 psi for a few seconds without incident.
Upon inspection, the wastegate appears to be functioning correctly.
Much of the problems on the KC trip may be traceable to the manifold vacuum/pressure problem. Nonetheless, smooth running for the most part, good gas mileage–as the breather hose plug may have been in place. With the hard pulls under boost (Duke) the plug may have become dislodged (blown loose). This would explain (a) idle hunting, (b) inability to get any appreciable boost, (c) poor throttle transitions on deceleration, (d) BOV activation under engine loading.
12/17/07
Some difficulty in getting engine to catch. Usually car will fire on 2nd cranking pass after fuel pressure has built up–5 to 10 seconds of cranking. This time it took 6 or 7 cranking efforts, close to 30-45 seconds of cranking before firing, then 2 or 3 tries to catch. Possibility that the tuning Justin did to the TEC-3 this past June may have had the open breather line (vacuum leak) condition and the settings were(are) incorrect as a result.
4/13/08
It was nice out. So I thought I’d leave it out.
First really decent weather in several weeks. Streets dry, tho’ still a bit of sand. Three tries to get it to catch; some roughness for a few min until coolant up to about 140deg F. Pulls readily from idle, as long as one is judicious about the clutch. Runs thru neighborhood. Vacuum gauge moving readily up to ~3 to 4 psi. Nothing more aggressive attempted due to locale, surroundings. Moving from ~14 in of vacuum to 3-4 psi boost was smooth and uneventful, with no hiccuping. We just may have addressed the stumbling with the vent hose fix. (I hope.)Oil is clean, very light amber–as I would expect with only about 180 miles on it since the
change in mid-November.
4/29/08
Emissions run-thru in Castle Rock. Failed test.
HC 5.0452 fail
CO 20.8228 fail
NOx 2.6997 pass
The techs had let the car sit for nearly ½ hour, so cats were stone cold.
5/1/08
Car into MileHigh Perf. At Jay’s suggestion, swapped out the Elston exhaust for the 2-cats-in-series one Justin and I built. Run thru emissions on a retest at the Mansfield Ave. location. Passed without any problems.
HC 1.4927 pass
CO 9.6020 pass
NOx 0.5306 pass
Jay’s analysis was correct. High HC and CO probably a function of valve overlap leading to unburned fuel in the exhaust. The location of the 2 cats in series–much closer to the downpipe --probably gets thing hot enough to burn off the HC and catalyze the CO into CO2. “Emissions” exhaust swapped for the regular unit after the tests were completed.
Plates renewed; now on a May-to-May cycle.
5/28/08
New trunk carpet fabbed at Euro Auto Interiors. This covers the aux tank. Underlayment is ¼” felt and is attached with 2” wide industrial Velcro. The main trunk floor area got a fitted piece of 1/8” lauan plywood to provide some floor rigidity and protect the spare. Carpet is loose over the plywood; depending on how well it stays put, I may attach some additional Velcro pads for location purposes
7/29/08
Took That Thing up thru Poudre River Canyon behind Ft. Collins for an extended session of twisty bits. Thence over Cameon Pass (lots of sweepers) into Walden and North Park. Lunch @ River Rock Cafe. Killer French Dip. South out of Walden towards Granby and Berthoud Pass. Lots of open country with big straights. Caution advised, as this is ranching country and often as not you will find farm equipment occupying a lane-and-a-half when you don't expect it.
Got a bit froggy on the pull up the west side of Berhoud; big switchbacks, relentless grade. Well and truly into the Loud Button. I expected more drama pulling thru the hairpins, but the Quaife diff really keeps things dug in.
Point. Brake. Turn in. Throttle. Leave. Repeat.9/18-9/21/08
Photo opp for elder kid to try out a new lens on his digicam. Pics on Loveland, east side of Independence. A number of these got posted on the mye28.com "Eye Candy" subforum.
Additionally, we got about an hour of video on the North Park/ Berthoud/Independence runs. What's interesting to note is the vids are absolutely unforgiving in displaying poor driver technique
. Additionally, the vids don't convey the speed levels terribly well; the center stripes don't appear to be going by all that quickly, and I know how fast I was going at the time.