Advice on - MLS head gasket leaks

[Duke]

A lot of good advice from some very high HP FI BMW guys from BimmerForums on the Cometic MLS gasket leaks. You will find that removing the rivets and using Hylomar/Permatex between layers is becoming very common for high HP engine builds. Additionally, the head prep...i.e. RA below 20 is important.

Take a look at this thread on BimmerForums FI board - Click Here

[chrism]

The last post as of right now says it all:

First to track down the weak point of the head, we need to compile stats of where exactly they tend to fail, so we can see if it follows a pattern.

They dont know the cause of the failures any more than you do. If there were 20 of the headgasget failures lined up side by side and the failures were all at the same point there would be something to go on. The only picture I see is of a BURN OUT between cylinders. If as the first post states the gasgets are work hardening and cracking your hylomar idea is nothing more than a longer term bandaid. the metal is still going to flex and sooner or later the goop will not hold. Try a tuning improvement

MLS gasgets work too well on too many other aplications without all the intensive BS. There is more than likely a user-error problem occuring. Maybe it is the RA, maybe its headstuds not being tightened or being overtightened, maybe the design of the head really isnt solid enough to support the use of a MLS gasget..

[Shawn D.]

Chris,

The word is "gasket," not "gasget" -- even Duke gets that one right!

-Shawn

[Mark 88/M5 Houston]

I read that thread and didn't find any definitive conclusion or fault defined other than "the" head gasket is the weak link in the system. Adding a turbocharger or supercharger to a normally aspirated engine at home is all ways an adventure; especially when few of us have engineering degrees (related to internal combustion engines) or the engineering departments of a manufacturer to resolve or suggest resolutions to the problems encountered. The problems related in the thread are the same as encountered when boosting beyond the designed limits of a turbo engine provided by a manufacturer.

Expecting reliability out of a relatively small displacement engine when turbo or supercharged to high horsepower levels is not logical in my opinion.

[Duke]

Expecting reliability out of a relatively small displacement engine when turbo or supercharged to high horsepower levels is not logical in my opinion.

I agree completely. I found the post informative in the different methods that are used to prolong the MLS gasket life. There are ways insure a MLS gasket never leaks: O-ring the head and block and use adhesives. Problem with that is, you will then destroy engine components and not be able to get the head off.

[chrism]

oops...kant you sea I kant speel?

Chris,

The word is "gasket," not "gasget" -- even Duke gets that one right!

-Shawn

[Ken H.]

The problems related in the thread are the same as encountered when boosting beyond the designed limits of a turbo engine provided by a manufacturer.

Expecting reliability out of a relatively small displacement engine when turbo or supercharged to high horsepower levels is not logical in my opinion.

True, dat.
A few points which I outlined in my "Lucifer's Hammer" screeds. When Dinan was working on turbocharging the M30 motors back in the late '80s and early 90s, they found that turbocharging materially shortened the life expectancies on the motors. To establish some baselines, they obtained a tape which was used to "manage" the loadings on an engine dyno. This file duplicated a very quick lap at the Nordschleife. Run in a loop, this allowed them to run a bone-stock M30B35 motor in a high-stress simulation virtually indefinitely.
The motor was shut down at appropriate intervals to change oil, etc. and do essential repairs, such as replacing water pumps, plugs, adjust valves and so on. The motor went for about 160,000 miles before the rings and bearings began to give up.

They then went thru the same drill with a turbo'ed M30B35. This was set up in the same configuration that Dinan was planning on releasing to the public--T04 turbo @~12.5 psi, air-to-air IC, O-ringed block, Crower rods, forged pistons with IIRC, around 8:1 CR. and a first-generation Turbotronics engine management chip. These motors were turning out somewhere around 390-400 hp. Russ C may have a better memory than I do on this topic.

These motors went around 40K before things began to Go South--rings and bearings showing the strain. Since Dinan was offering a 36,000 mile/36 month warranty on parts and labor, some clients were bringing the cars back . . . not a good thing from a business standpoint.

The end of this story is that the costs and reliability issues on the FI M30s were a major factor in Dinan's decision to get out of the turbo market.

In effect, the turbo setups doubled the power output over a stock M30B35, but at a cost of about 1/4 the life expectancy.
Not a good tradeoff in Dinan's opinion. Note that this was with boost at less than 1 bar.

This information was related to me by two of Dinan's (now) senior people, Declan Doyle and Jeff Hecox, who were intimately involved with the original turbo project and knew all the details. I have known these gentlemen since the early 80's. These conversations came about as I explored the "Lucifer's Hammer" concept with them before I began the project. Bottom line in that regard is that Dinan Engineering was out of the engine modification business. If you want details, pull up the "Lucifer's Hammer" posts I did on the FI subforum a while back.

What's worth noting in the BF.c thread is the problems seem to occur when the boost levels are pushed beyond 15 psi (1 bar). The people who have experienced the failures are not supplying much information regarding how their engines were prepared, other than "yeah, I used ARP studs," etc.

Somehow, the expectation seems to be that one can simply stick an MLS gasket in there, screw down the head fixation and go for the roses at (plug in whatever boost number here) and never see any consequences.

"oooh. we got XYZ hp on the dyno but the &*()$%! thing let go after six pulls. The HG is a piece of shit."

Where I'm going with all this is I do not think the issue lies with the gaskets themselves. I am of the opinion that drilling the rivets and coating the surfaces with Hylomar will extend the gasket's life expectancy. Some of the posts in the BF.c thread allude to heat-cycling frequency as a possible failure cause. Paul B. advised me that my motor, as built, would require allowing the engine oil temps to get into the 150-180 degree range before putting any severe stress on the motor. This means that temps throughout the power plant--block, head, internals, turbo, oil cooler, etc. had 'normalized,' and clearances were where they were designed to function. That, and there was some pretty sound reasoning done in limiting boost to 15 psi.

On this latter point, the generation of HP is a function of moving a given mass of air, not necessarily doing it at a higher pressure. In other words, using a GT-35 at 10 psi might give you 55# of air per minute, whereas a T-04B might require 18 psi to deliver the same mass. Concurrently, the lower the boost pressure, the less heat added to the air charge, which means more efficient combustion. Obviously there are a lot of tradeoffs that go into the turbo sizing and boost level analysis, but I come away with the impression that the boost junkies are all about wham, bam, thank you, ma'am as far as power outputs are concerned. If this means once-a-month rebuilds on the motors, so what?

Given that our engines were designed for sustained running (see recent posts about people getting 200K+ miles) I'd rather have something that can see 120K or more with a moderate boost level, than drop my wad after one or two evenings at Midnight Auto Club.

My $.02

[Jeremy]

Given that our engines were designed for sustained running (see recent posts about people getting 200K+ miles) I'd rather have something that can see 120K or more with a moderate boost level, than drop my wad after one or two evenings at Midnight Auto Club.

And here I thought nobody understood my desire to keep the boost (relatively) low on my cars.

Jeremy

[Duke]

In effect, the turbo setups doubled the power output over a stock M30B35, but at a cost of about 1/4 the life expectancy.

That is why I have alway felt that bolting a turbo to a high millage M30 is just wrong. The ability to replace the engine with another "junk yard" engine is a very bad argument.

[Jeremy]

In effect, the turbo setups doubled the power output over a stock M30B35, but at a cost of about 1/4 the life expectancy.

That is why I have alway felt that bolting a turbo to a high millage M30 is just wrong. The ability to replace the engine with another "junk yard" engine is a very bad argument.

In a high stress application, sure. Nothing puts wear and tear on a motor quite like a demanding track does. However, most of use are driving these on the street, with possible occasional track usage and short instances of using the full power available. I've got 26k turbo miles on a 233k mile original block with no changes in oil consumption or compression. To me, that says a built engine is not neccessary for the street.

Had I put the system together for a dedicated track car, I probably would've done things very differently.

Jeremy

[M. Holtmeier]

So, what the guys from the BF thread are saying is that you are better off to run a lower boost with stock gasket and studs? If our engines weren't designed for them, wht use them. Or, do I have the block o-ringed now while it's still at the machine shop? (Stock bottom b34,b35 head)

[Duke]

So, what the guys from the BF thread are saying is that you are better off to run a lower boost with stock gasket and studs? If our engines weren't designed for them, wht use them. Or, do I have the block o-ringed now while it's still at the machine shop? (Stock bottom b34,b35 head)

If you O-ring the head and block and use a stock HG you will be set. You can also use a MLS gasket with the O-ring head and block. How much boost do you want to run daily is what you need to consider.

[Boru]

In effect, the turbo setups doubled the power output over a stock M30B35, but at a cost of about 1/4 the life expectancy.

That is why I have alway felt that bolting a turbo to a high millage M30 is just wrong. The ability to replace the engine with another "junk yard" engine is a very bad argument.

This is a good argument if you are going to run at boost for every minute that the engine is running.

Given that the majority of these engines will be at boost for, say, 1% (and that's being generous) of the total mileage then your 200,000 mile expected engine life might be reduced by 1500 miles.

The transparency of what is going on in this forum is laughable.

[Boru]

The transparency of what is going on in this forum is laughable.

Good, why don't you go away too then? Go laugh elsewhere.

Hey! Now there's a good idea!

[chrism]

No that isnt a good idea.

The transparency of what is going on in this forum is laughable.

Good, why don't you go away too then? Go laugh elsewhere.

Hey! Now there's a good idea!

[M. Holtmeier]

Cometic Phusion.

I emailed Cometic about this. It's only available in 0.051" thichnesses, but isn't the b34/b35 combo already around 7.3/7.6 cr with stock pistons?

[M. Holtmeier]

The transparency of what is going on in this forum is laughable.

Good, why don't you go away too then? Go laugh elsewhere.

Hey! Now there's a good idea!

No, this is laughable.

[Kyle in NO]

Why would it be wrong? If you have much more time than money, who cares if you use it for 30-50k and swap it out? Driving the damn thing on the highway is the same with or without the turbo, which is where mine spends the majority of its time anyway. I'd rather swap mine out after 50k than buy a factory long block and have it last maybe twice as long. If you do something stupid like overboosting or running lean with a high mile motor OR with a brand spanking new unit you will end up with the same result....damage. Your wallet will just be signifigantly lighter with one of the methods. Why do you think hot rodding has always been based on readily available, cheap components and junkyard runs? Sure a technological marvel is nice to gawk at, but it has never been for the average Joe hot rodder....

I'm also wary of trusting your ideas of how to do BMW performance, as to me your efforts have never really performed particularly well (for very long anyway) while those of us using your suggested "bad ideas" have enjoyed many trouble free and great performing miles? Its all how you look at it...you've done some cool things with your cars, why talk down to those who'd rather not dump all their money into having the ultimate ride? What's wrong with being 98% there and happy with it?

[M. Holtmeier]

To each thier own.
So no one cares about looking into better solutions for combustion sealing? I've already been through high school and spent enough time with junkyard builds. I think we're moving backwards here a little. My head gasket never failed, but it was the resilience of the engine that nudged me to start fresh, because I want something nice.

[Jeremy]

The question is, where do you want it to fail?

If you manage to spike the combustion chamber pressures, either with bad pre-ignition or an overboost situation, where do you want the system to fail?

Personally, I think headgaskets are cheaper than rods and pistons, so I'd rather have the headgasket as the weak point. If you make the headgasket absolutely indestructible, it'll just fail at the next weakest component if something goes wrong.

Jeremy (stock headgasket and ARP studs for 26k miles)

[turbodan]

I'm another one for the stock head gasket with some good studs. I lifted the head off the stock gasket at about 22 psi. Thats not the fault of the gasket, but the stock bolts.

When the gasket deforms and literally blows out, its time for a gasket with more integrity. I dont think an MLS gasket should be automatically included in a rebuild just because its supposed to be better. I'll think about one if I actually destroy a stock gasket, but I havent done that quite yet.

Thats the way I see it.

[M. Holtmeier]

I'm another one for the stock head gasket with some good studs.

I think that's where I'm at too. I got a reply back from a Brandon Hare at Cometic Gasket and the Phuzion MLS won't be out for any of our apps. for at least 6 months. With a fresh engine, I'm not thinking about pushing it. It's going to live at .5 bar for awhile until everything is nice and broken in. A couple of questions for you guys running stock hg and studs;
What brand or source do you recommend?
Jeremy, what's your boost set at for daily driving?

[red535t]

interesting;

If I were to do it again,and i probably will,I'll install studs and a a MLS gasket.

at the moment im running 15lbs with a steel/graphite gasket with stock bolts.did a re-torque at 1000 odd miles to 120nm.
this was after the engine was broken in and then the blower was tacked on

no dramas but its running only on weekends and have only clocked up 2000+- miles with the extra power.
so I dont know how long its got before extra $$ will be need to be spent.(at this rate it will last longer then me,hopefully)

Whats info out there on intake temps?
lower is better for power and head temps.but will it also lower the combustion chamber pressures??

just a thought,marty

[turbodan]

I believe the reduction in intake temps will increase combustion chamber pressures. Colder is denser, so you pack more fuel and air in there with lower intake temps. More fuel and air means more combustion chamber pressure.

[Jeremy]

I run 10psi on Pokey, 12psi on the red car. Red car has MLS + studs.

Jeremy