V-12 Engine into 308 Build, over on Grassroots

I believe it is made by Pentosin. It is easily found as BMW branded coolant.

The way I’ve heard the story told is that BMW build an engine with too fine of coolant passages that were clogging with aluminum sulfates so, as mitigation, they commissioned (or at least licensed) a coolant specifically formulated to be easy on aluminum.

 

I saw clear signs of coolant migrating from the liners so put a thin film of high temp RTV in their contract faces with the block and where they touch.

Did you get the engine up to temp? If not it appears the problem is there before things start expanding. This suggests that your static sealing is not working and my guess is migration into the head gaskets from the liners. Before you pull the heads I’d put some coloured water into each cylinder at TDC and a little air pressure to leave traces of where it is going. I wouldn’t go with a copper shim as composite is more forgiving with movement due to different expansion rates.

I would get it sorted outside the car, can you rig it up to run outside the car?

 

I brought it to about 60C the first start theen 80C the second, so yes up to temp...but was it leaking from the get go after passing what I did to leak teat it?...sure it could have been. This leaks this go were a lot smaller than the last attempt, the leaking cylinder started without ether and would stay running as long as the mixture was rich so a definite improvement but also makes pretty much impossible for me to know when exactly the leaking began other than says the plugs were not noticeably wet after the first shorter run and did after the second longer run.

I don't think I will put water into the cylinders on purpose....it will get down into the rings and pit the iron cylinders. Maybe something like manometer fluid which is a red dyed kerosene or similar....I'd need to think about that and how to get it to flow...maybe if the engine was upside down? not sure. But I do know its the end cylinders and I'm quite sure I know why so I'm not certain this would tell me a lot more....the pressure sensitive film Scott suggested maybe could maybe add some confidence that the shims I'm planning to add are helping but I don't really know the acceptance criterial so helping and working are 2 different things.

My current thought is let Scott tell me what the factory gasket shim is and do something similar....although I'm remembering a pretty rigid QV head gasket that had shims where composites I have are the older more compressible style like were on the 400 when I pulled it apart so probably more shim is needed to get a similar effect....lots of guessing.

Getting my dyno setup or just the run stand part has been a topic of discussion for some time....but as hope springs eternal each time the engine is out I believe it to be the last time so not worth the time, expense, or delay to setup an external run stand setup. Each time I've been wrong, but this time will be different

 

When all else is lost, at least we have hope . Do you think it’s insufficient clamping at the ends? No chance of a tiny crack or hole from the welding? I would use a thin film of high temp RTV both sides of the gasket (except near the cyl rings), torque it down only lightly, full torque after 24 hrs, and use the dyno or run stand. You just know Murphy’s watching you and not putting it back in first will mean it doesn’t leak.

 

Love the optimism Mark. That is why you will win this fight.

 

It could be a welding issue....I don't see and odd its only the end cylinder, it but its possible. I'll probably retest the heads while they're off

I think its OVER clamping on the ends deforming the heads and creating a leak. The old gaskets that start life at 0.059" are now 0.055" in most places but are as low as 0.053" on the ends. Te studs on the ends are only acting on 1 cylinder rather than 2 so double the clamping force which is almost certainly deforming the heads and no doubt way ferrari adds metal shims to the ends of their head gaskets. I'll guess at the right shims and again try sealant and this time it will work

 

Checked, double checked, used two different gauges... Shim measures 0.007" but...buuuuut... It also wraps over the edge roughly 3.5mm and that edge is 0.009"~0.011" thick.
I can draw up a quick layout for the pattern if you want, but probably not till tomorrow. The shim also is constrained under the fire ring about a millimeter.

 

Maybe I missed it but why would your 12 cylinder leak due to lack of metal ends on the gaskets but not on other 12's? Ive used composite gaskets on 2V and 4V flat 12's without the steel ends and never had a leak, even bench testing before its run through a heat cycle and (knock on wood), none have leaked since.

 

I sketch would be great! I was kind of guessing the support need to increase with distance and again I'm pretty sure the comectic composite materials more compliant and what ferrari used on QV/TR engines so I probably need a bit more support.... PROBABLY...

 

hmmm, that is new information.

I thought ferraris switched to from the soft black unsupported head gaskets to the harder feeling tan gaskets with end supports at the same time they switched to the deck supported liners. My old use gaskets are 55 except the ends that are 53 thou....so there is for sure a 2 thou bow in the head in the last inch which I'm assuming is opening a gap just to the inside of the studs. So looking at the old gaskets and that its the ends that leak the need for additional support made a lot of sense to me.

Perhaps my challenges are in large part a problem of my own making. I converted the 400 block to deck mounted liners...but the deck is thinner than ferrari used on the later engines designed for this style liner. I also cleverly opened the bore up to from 81 to 86mm leaving only flame ring and no gasket material to seal the cylinders...hence the need for sealant
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If you mean the Elring gaskets that are black, I avoid them at all costs. Made in Brazil now I believe.

Looks like your liners are embedding into the gaskets nicely. Maybe the steel ends are the answer in your case if the head is bowing. If it was bowing .002" I would want to know what the cam saddles are doing. You can check them on the bench then torque on the block to get a good idea of how much the head is bending and where.

 

The 400i had black head gaskets when I pulled it apart, that is what I was talking about and just assume that is what ferrari had used on all the older "pressed liner" engines...but it was just a guess.. This looks very similar to the material cometic is using and just feels different to what I'm remembering as tan gaskets in the QV..I remember those feeling hard to the touch buit maybe I'm just imagining this....its been 15 years now I guess

I reamed then lapped the cam jounals with the heads on...so they should be straight in run condition......until I add shims I guess

 

I know it a pain but I would be inclined to set up a run stand at this point

Then they should be out of alignment on the bench. Ideally the journals would be lapped after some heat cycles and the heads took a set in the gaskets as impractical as that is.

Were you getting pressure in the cooling system? I didn't see mention of that, just consumption and funny readings. If not then your coolant is being fed into the cylinder on the intake side of things.

 

How would I know? The cap will dump anything above normal won't it?

I do know there was no sign of anything in the ports or anywhere else after pressure testing the system @15psi for a week so I'm pretty sure it was sealed before I heated it up. I'll probably use a higher test pressure this time.... I tested the heads at 45psi I think it was after fixing the coolant leaking holes my port welding had left so for sure they were sealed at that point in time.

 

The opportunity to check for combustion gasses is lost with the engine out and apart. More time diagnosing it in car would've eliminated certain things that are hard to test now, just sayin.

Might not be a bad idea to bolt the heads back on and pressure test it as an assembly. You could even introduce air into the cylinders and see if you get bubbles into the water you fill the block with.

 

Just my O2 but I second pressure testing the assembly before you put it back into the car.

You mentioned earlier it was leaking from the get go so temp had little to do with the sealing for the previous attempts.

It would be a simple loop of hoses joined with a radiator cap fitting plus a standard coolant pressure tester.

Yes it is possible it might pass a cold test and leak when it gets to temp but for sure if it leaks on a cold test it will leak on a hot test.

 

As I said a few post back....it spent a week @16.5psi before going in last time with no sign of a leak, no loss of pressure and I put a camera in the ports and bore, it was dry.....this time I'll use 30 I guess
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Evans is mostly propylene glycol. While it expands in volume a little bit it doesn't build pressure like water based coolants. Hence there's little to no pressure on the system when at temp.
It's the surface tension, molecular size and gaps that create leaks.

 

I think Paul was talking about the cylinder pressure leaking into the coolant creating pressure in the coolant system....which must have been happening but the cap also must have dumped it.

I love not worrying about corrosion...but back to water I go and hopefully both the leaks and heat issues will be gone.

 

Yes thats what I meant,

Im not so sure 30 psi is required but 150 psi in each cylinder 1 at a time might reveal something. No cams, pistons at tdc or bdc doesn't matter. See if you get bubbles in the cooling system.

 

I’m not even sure of 150psi is enough. Cylinder pressure when running dynamically well exceeds that not to mention the heat. Any harm in machining a steel strip nearly the width of each end of the cylinder head that is close to or slightly thicker than the fiber gasket crushed thickness, perhaps combined with increasing head torque 5lbs.

 

Better than not trying. 150 in the cylinder might be better than 30 on the coolant side.

 

I agree. In the end it comes down to sealing off the water passages from the combustion chambers. I would become an alcoholic by now using the car as a test stand. I have had to pull engines multiple times and there is no joy in the process or hoping that this time.....it hangs together.

 

You guys reminded me of this
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I got 1 head off yesterday and sure enough #6 is spotless inside
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1&3 were black so they were much improved...but I was too slow with the camera. They were a little glossy so I wiped them and they wiped clean pretty easily so a slow leak I guess
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A couple other things caught my eye like were the heck is the sealant? I see traces were the gasket wasn't touching anything and maybe a tint of color but this head sure wasn't glued on.
The other thing is other than #5 there were small cleanish patches on all the pistons and looking in the intake ports there is a corresponding bit of gloss on a portion of the intake valve above. None are wet/glossy across the bottom like coolant pooling in the port other than maybe #6 the valves are soaked everywhere......but there is nothing similar on the port itself and last assemble the valves in 1 & 3 looked just like 6, soaked. This is telling me they are getting wet from coolant spraying on them when they are opened.

.....which brings me back to where the hell did the sealant go? Maybe I should have let is sit at very low torque as Derek suggested or try a different sealant....need to think about that.