Mistral/Sebring 4liter head gasket problem

Tom it sounds like you may have machined the head and the grooves no longer are there to contain the small ball bearings. These grooves are very important to prevent the rubber from being pushed out from the water pressure. I feel this system is by far the best way to seal the head on these inline six cylinder engines. It does take extra effort to install them but if done right will last a long time.

 

The one piece gasket isn't available for the 4.0L. So you will have to use the fire rings/rubber head gasket and 11 ball bearings. The perimeter of the cylinder should have 2 small grooves per side. Shops often re-surface the head but omit the grooves. The grooves and ball bearings prevent the gasket from squeezing out. rubber gaskets thickness should be 0.010" thicker than the fire rings. I always glue the ball bearings on the gasket to prevent them from falling out during installation.Hope this helps.

 

I have a question. is there anything different between the 3.5 liter six and the 4 liter six other than the bore size for the pistons? I'm referring to the water passages, cylinder head dimensions, etc. If not, then Cometic Gaskets can make a gasket that can be properly sized for the 4 liter bore using one of the modern gaskets than have been run up for the 3.5 liter engines as their pattern. I know this as I have had Cometic make up replacement gaskets for my Bora including an engine with a larger than standard bore size. Unfortunately, I don't have enough information about the six cylinder cars to know if this is possible or not. I'm looking for enlightenment!

 

The 4.0L engine has an 88 mm bore vs 86mm on the 3.5.
The issue with the 4.0L and using the single piece head gasket has to do with the fact that there isn't enough room for the gasket to compress completely without extruding inside the liners. This is mostly due to the fact that the liners are too close to each other. The fire rings is the way to go on the 4.0L. The other problem, is finding an experienced shop to do the job correctly.

 

I think they may have supplied a couple of extras since they are easy to lose. You do not need them on the outside front since the spacers keep the gasket in place. To keep the fire rings in place when installing the gasket I spray the fire rings with Copper spray gasket. Make sure you have the grooves in the head and do not use a gasket sealer for the rubber gasket.

 

My suggestion is go back and read the answers supplied in the above post.

 

What's your torque sequence?very important!
What thickness fire rings are you using?
Thickness of the gasket?
Did you use glue to hold the ball bearings?

Head could be warped.
Liners could be misaligned.

 

What pleasure is your radiator cap? Max 7 lbs.
Have the liners been decked?
All liners should be flush with the block, are they?
Rubber sealing ring should be +- .075 thousands
Fire rings and spacers should be + - .051 to .054
that would give you a 20 thousands crush on the rubber sealing ring.
Something is very wrong if you have the above specs.
Having done 3 of these on 3 different cars in the last 3 years including AM101.1121 most recently (see below photos) I can tell you this works!
Good luck.
FGM
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Eogorman was very right. Your head surface may have been machined too much which would eleminate a small groove which runs around the gasket sealing surface area, this groove corresponds with a small triangular protrusion on the rubber gasket.
This protrusion and the groove work together to retain the gasket in the proper position.

Frank is also correct too much pressure could also be your problem. These engines are very particular and we're carefully engineered.
MHO

 

After all your pain and effort I'd suggest you meet all the check mark conditions outlined above for a successful build this time, including the groves in the cylinder head.

 

That was number one on my list....
FGM

 

There was a guy on ebay that had some gaskets made that were too thick for the 6 cylinder engine. You might call him and get the measurements. I know I bought one several years ago and never used it because it was too thick. To use it you would need to get larger ball bearings to lock in the gasket too the head and have new shims made up for front and rear. I think the listing is under ovrst2. I just checked and He is still selling head gaskets but I do not know if he still has any of the old ones. I may have one around some where if you are interested. Of course the right solution is to machine the liners to be the right height

 

We could never get that rubber/fire ring/ballbearing setup to work either so we had a run of regular head gaskets made for the 6 cylinder cars. As I recall they were terrible and came apart at the fire rings, so we had solid copper gaskets made and we were so happy with them we now only use solid copper. I have reused them 3-4 times on the 16 plug V8.

It's not going to solve your sleeve machining problem, but good to know you have another option.