1FastRedSC

Ok, here's the story, it's a 951 with 104mm steel sleeves, je pistons, blah blah blah. Anyhow, we can't get the head to seal right. It seems to leak more when cooling down, then when warming up/hot. And it doesn't leak at all when cold. We are trying to use a factory head gasket to seal it (have a steel head gasket but took it out when other things started going wrong). Oh, also, it's got arp headstuds, anyone want to take a stab at how to approach this?

David Floyd

Head and block have been checked ?

I use a Cometic MLS gasket with similar setup to you, 106mm sleeves, JE, ARP.

How are you torquing the ARP headstuds ?

Matt Sheppard

Yes, how flat is the block deck and same (?) on the head.

1FastRedSC

I checked the block deck, flat all across, not even the smallest of my feeler gauges could be tucked under the straight edge. Plus i checked the head for warpage just in case. Torques, i used the factory torque since i didn't get any other torque spec with the head studs. Everything was cool the first heat cycle, after that it would start to slowly leak.

David Floyd

I torqued at 25-45-75 ft lbs factory pattern, let set overnight (per ARP) then go over once again at 75 ft lbs, continue build.

Are we talking coolant leak ? from what area ?

1FastRedSC

Coolant leak, and not out of the block, but into the combustion chamber. Actually in retrospect i think running straight water may have been a bad idea too. When we slapped it together, we didn't have any antifreeze laying around, so we just put in straight water so that we could fire it up and start tuning.

Sam Lin

Straight water is not the cause of your problem.

Sam

David Floyd

I would retorque the head studs and cross your fingers.

Beyond that a teardown is in order, check head, block and sleeves with a straight edge.

How are your sleeves installed ? Do they have a ledge up top that bottoms out against the milled down stock bore or are they just pressed inside the bore with nothing to stop the sleeve from moving up or down ?

1FastRedSC

They have a ledge. And the last time we were having other issues with the motor, i took it apart and measured with a straight edge across the deck several times measuring all four cylinders at different angles. And as stated above, the smallest of my feeler gauges couldn't fit under it, that tells me that it's perfectly flat.

m42racer

If you are leaking into the Chamber, then the H/G will show signs of uneven clamping of the Fire Rings. If the Fire Rings look good, then its not the H/G. Have you pressure checked the Coolant system, when the engine is hot and cold? Has the Head been pressure checked and Zyglow checked? If water is getting into the Chamber, then the water system should be pressurized under boost above the Cap value. Your not seeing something. There is dye you can buy to see if combustion gases are entering the coolant system. Re check the flatness of Block deck. Lap it to see if there are any high spots. Look to see if the BTM of the Block bores are machined further than the BTM of the Liners. Re check the Flatness of the Head. See if it has any high spots. The installation of the Liners is also very critical. If the block was machined to receive the Liner Flange, and the relief on the corner was too small compared to the radius on the Liner, this can cause the Liner to lift under temperature. Something else, the smallest feeler gauge shim in a typical set is normally 0.002". You need to be measuring less than 0.0005". How straight was the straight edge? If you cannot get 0.002" under a good straight edge, then you have 0.002" or less. 0.002" becomes somewhat larger in theory when it comes to some mystery water leak.

I would highly recommend you use the MLS Gasket next time over the stock Gasket. Also, you do not have to retorque the MLS Gasket after the initial torquing. The embossments on the Gasket will certainly help more than any standard type Gasket. If you had problems with this type of Gasket in the past, then there was something else wrong. If you cannot find it and do not have at your disposal all of the tools to check, get it done by a professional. It may cost upfront, but at least you won't be going back in to find it again.

1FastRedSC

When i speak of previous problems, it was when we were assuming that the head was leaking, and it turned out that the turbo we had just boughten had a hole between the water and oil passages. The straight edge is a snap on straight edge.
Oh, and what is an MLS gasket, i have a custom steel gasket laying on the shelf, a copper one made by broadfoot racing, and the factory one inside the motor.

David Floyd

Copper head gaskets are very very hard to seal correctly.

MLS = Multi Layer Steel from www.cometic.com

m42racer

There is nothing wrong with Copper Gaskets. some are even made from Aluminum. There is a special technique to sealing them. I've seen it and it works real well. The MLS is still a better choice when available. I have sent you a PM regarding who has them for the 2.5L Block in 104.00mm bore size. They can also do all the checking for you if you need help.

m42racer

Did you find out anything?