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My new TCD manifold and turbo arrived today.
It was resurfaced before it went back together. I dont think it burned any coolant on the test drive, but there was a lot in the oil. If its leaking that much into the oil at the head gasket I would expect to see a lot of steam out the tailpipe and some external leaks as well. The amount of crap in the top of the head leads me to believe its cracked right under the cam.
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I've got one thats cracked there too. It came on a junk motor, and I ended up using the block from that motor. The head came with the car, and had about 234k on it when it came apart. It worked good for a year or so. It never overheated in the turbo car.
I guess I will check the block when it comes apart. I hope to find a crack in the head though. That sure beats swapping the block out.
I guess I will check the block when it comes apart. I hope to find a crack in the head though. That sure beats swapping the block out.
I've got a complete 2.7L SuperETA engine, that is taking up space. I'll sell ya parts cheap, just to get it gone. Just really want some $$ for my time. Good head and all.turbodan wrote:I've got one thats cracked there too. It came on a junk motor, and I ended up using the block from that motor. The head came with the car, and had about 234k on it when it came apart. It worked good for a year or so. It never overheated in the turbo car.
I guess I will check the block when it comes apart. I hope to find a crack in the head though. That sure beats swapping the block out.
Took almost two hours to get the head off this afternoon. That may be a new record.
As soon as the valve cover came off it was apparent that it was a cracked head. I couldnt see a crack, but there was a little blue puddle of coolant right by the #5 exhaust valve. Theres no way thats going to pool up right there unless its originating right there. As soon as the head came off, it was clear that the head gasket had sealed properly. It looked great. So the block is good.
Even with the head fully disassembled I still couldnt see the actual crack. Looking at the junk head I have thats clearly cracked, I was starting to think I had a real mystery. It took about 15 minutes just looking at it to actually see the crack, despite it being about 2.5 inches long. But its definitely there. Its just in the sand cast part above cylinder #5, it didnt go across the cam bearings so it doesnt stand out. If you're not looking for it like you're absolutely sure its there you can easily miss it.
Thats good news. I got a head in town that I've got drilled and ready to go. I just need to swap in some double springs and check it for flatness and it'll be ready to go. Now that I found the problem I'm feeling pretty good about it this time around.
As soon as the valve cover came off it was apparent that it was a cracked head. I couldnt see a crack, but there was a little blue puddle of coolant right by the #5 exhaust valve. Theres no way thats going to pool up right there unless its originating right there. As soon as the head came off, it was clear that the head gasket had sealed properly. It looked great. So the block is good.
Even with the head fully disassembled I still couldnt see the actual crack. Looking at the junk head I have thats clearly cracked, I was starting to think I had a real mystery. It took about 15 minutes just looking at it to actually see the crack, despite it being about 2.5 inches long. But its definitely there. Its just in the sand cast part above cylinder #5, it didnt go across the cam bearings so it doesnt stand out. If you're not looking for it like you're absolutely sure its there you can easily miss it.
Thats good news. I got a head in town that I've got drilled and ready to go. I just need to swap in some double springs and check it for flatness and it'll be ready to go. Now that I found the problem I'm feeling pretty good about it this time around.
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I'm really thinking about lowering the compression ratio so I can run more boost this time around. I was considering it before but I ended up putting it together with a just slightly thicker stock HG. I dont know exactly how low it'll go from 8.5:1 with a .120" MLS gasket, but it should be good for more boost on pump gas.
![Very Happy :D](./images/smilies/icon_biggrin.gif)
![Very Happy :D](./images/smilies/icon_biggrin.gif)
I didnt get much done this weekend. I lost the water pump in my 83 on the way into work on Saturday, so I ended up doing a timing belt/water pump job on that instead. So I'll probably have the head resurfaced during the week and shoot for next weekend. I was just going to slap it on as is, but it would suck so much if I ended up having to do this again.
I'll probably check the block now too. I dont usually worry about that, but its got to be pretty much cherry to seal with a gasket that consists of three pieces of flat steel. I cant absolutely count on a 20 year old piece of cast iron to still be as perfectly flat as it was when it was originally milled. I know I've put it through hell, and I have no idea what it went through before I got it.
I do know that the head that was on the block when I got it was cracked across four cam journals. I didnt think much of it at the time, but then again I used to consider the M20 block itself to be pretty much indestructible. I know the block has worked well in the year since I've had it, but the stock head gasket doesnt require absolute flatness like the MLS does. I would hate to find that its not ready to put back together, but if the block does turn out to be faulty it would be a good excuse to order up a brand new super eta short block from BMW. That would be pretty sweet...
I'll probably check the block now too. I dont usually worry about that, but its got to be pretty much cherry to seal with a gasket that consists of three pieces of flat steel. I cant absolutely count on a 20 year old piece of cast iron to still be as perfectly flat as it was when it was originally milled. I know I've put it through hell, and I have no idea what it went through before I got it.
I do know that the head that was on the block when I got it was cracked across four cam journals. I didnt think much of it at the time, but then again I used to consider the M20 block itself to be pretty much indestructible. I know the block has worked well in the year since I've had it, but the stock head gasket doesnt require absolute flatness like the MLS does. I would hate to find that its not ready to put back together, but if the block does turn out to be faulty it would be a good excuse to order up a brand new super eta short block from BMW. That would be pretty sweet...
I can tell you that when I did my MLS I did not fool with the block. (other than cleaning it off) I did check it with a straightedge. It wasn't out much anywhere. I believe the issue with the MLS is more about the head prep. As long as it doesn't try to expand with both the head and the block it should be okay. What I mean by that is that since the head and block have different expansion rates, and it is steel like the block, it has to be able to expand at a different rate than the head. If the head is not prepped properly it will "snag" lets say, on the viton of the MLS. Over time with the heat and cooling cycles experienced it fails.
Certainly the more perfect your surfaces are the better it will work.
The fact that you cracked the cam bearing journal may have something to do with the fact your head was lifting on the back 2 cylinders. I can't imagine the cam likes to flex while rotating and I would say that your head did flex.
Certainly the more perfect your surfaces are the better it will work.
The fact that you cracked the cam bearing journal may have something to do with the fact your head was lifting on the back 2 cylinders. I can't imagine the cam likes to flex while rotating and I would say that your head did flex.
The motor is back together, it just needs a valve adjustment and a couple oil changes. I think I'll drain it out and run it up to temp once, then drain it again and see how it looks in there. There is a lot of nasty in there, and I think its going to be a pain to get rid of it. If I'm lucky I wont have any more coolant getting into the oil, so I should just have to get rid of the muck from the last little episode.
I am looking forward to tuning for the lower compression ratio. With an MLS and studs it should be good for 400+ at the wheels as far as I know. I'll probably spring for a knock sensor before I get back on the MBC though. I dont want to jack anything else up.
I am looking forward to tuning for the lower compression ratio. With an MLS and studs it should be good for 400+ at the wheels as far as I know. I'll probably spring for a knock sensor before I get back on the MBC though. I dont want to jack anything else up.
And it runs again. I'm cautiously optimistic about things at this point. No more coolant in the earl, no leaks that I have found so far, and it still pulls like hell. My restraint lasted about ten minutes, but thats okay. I figure with an MLS HG your probably alright to wait a little while on the head stud retorque. Its not going to squish much, if at all, being nothing more than three pieces of steel.
The cooling system seemed not to have a whole lot of pressure, but this could be due to my leisurely drive into the 'hood with the heater on full blast. I dont see any leakage on the block, but its hard to see the exhaust side with the TCD system. If its leaking coolant internally, its not leaking much, and I would expect rock hard hoses and system purging if it were a leak into the combustion chambers. And I know is that its not leaking into the oil, which looks perfect. So I think all is well at this point.
I'll have to wait until this weekend to say for sure that I've got it fixed for sure. But so far, no problems...[/i]
The cooling system seemed not to have a whole lot of pressure, but this could be due to my leisurely drive into the 'hood with the heater on full blast. I dont see any leakage on the block, but its hard to see the exhaust side with the TCD system. If its leaking coolant internally, its not leaking much, and I would expect rock hard hoses and system purging if it were a leak into the combustion chambers. And I know is that its not leaking into the oil, which looks perfect. So I think all is well at this point.
I'll have to wait until this weekend to say for sure that I've got it fixed for sure. But so far, no problems...[/i]
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Im going on two years with no retorque of the ARPs in my 240sx with a MLS headgasket. 18 psi daily with no signs of any leakage. Maybe I'll get around to it one day it just sucks having to pull cams to get to the nuts on the studs. BMW SOHC heads make this so much easier though. I wouldn't really worry about the retorque a whole lot - basically do it when it you aren't freezing your ass off outside in the cold.
After 24 hours and some retuning, it looks like its going to be good. The cooling system holds pressure, no leaks. No visible smoke from the exhaust, no oil loss. No problems.
I didnt expect the TCD manifold to be good for so much more power. Its a huge difference. I dont think it was able to blow down and fill the cylinders running the turbo diesel manifold, because its running harder on 12 psi than it was before on ~20. The midrange and top end are frightening. I could add another degree of timing anywhere on the map as it is and still be clear of detonation. Its quite remarkable.
I'm looking forward to getting on the boost controller in the coming weeks to see what it can really do with standalone injection, head studs and a 3mm MLS gasket. I guess I'll see how long it takes to get used to the vulgar kind of power its making on 12 psi.
I didnt expect the TCD manifold to be good for so much more power. Its a huge difference. I dont think it was able to blow down and fill the cylinders running the turbo diesel manifold, because its running harder on 12 psi than it was before on ~20. The midrange and top end are frightening. I could add another degree of timing anywhere on the map as it is and still be clear of detonation. Its quite remarkable.
I'm looking forward to getting on the boost controller in the coming weeks to see what it can really do with standalone injection, head studs and a 3mm MLS gasket. I guess I'll see how long it takes to get used to the vulgar kind of power its making on 12 psi.
Thats awesome! It's great not to be constipated!!
It is pretty amazing how adversely significant exhaust backpressure affects an engine. It's not surprising that it takes more timing now without detonation as, like you said, were most likely killing VE with hot combusted end gas diluting your charge due to the inability to blow down. Having things work the way they are supposed to is a great feeling.
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