Engine/Transmission (1994 - 1998) Head Gasket leak near thermostat?

[Caterpillarman]

Hello, I am new to the forum. I have a 97 12 valve that has a head gasket leak near the thermostat housing. I was wondering if someone has a parts list, and or any advise on reparing this problem. My engine is stock with 202,000 miles on it. I just got done repairing the dowel pin, I had to learn the hard way after it went through the timing housing. Any help would be great, Thanks. Caterpillarman

 

[MMiller]

First off, Cummins has a "head gasket kit" that will come with every gasket and seal to replace a headgasket. I would encourage you to pull the injectors before removing the head to prevent damage to them. As far as the head gasket repair itself, you really need to decide what you are going to do with the truck. Are you going to BOMB it? If yes, then you need to think about oringing the head for better gasket sealing and retention. If no, or not much(read less then @ 40 psi of boost) then mill the head flat, buy a cummins . 010"(or . 020" if the head needs more taken off to be flat) over head gasket kit and new head bolts, and be done with it.



Caterpillarman, hmmm. I work on the yellow iron, do you?



Michael

 

[WDimig]

p/n for kit

caterpillarman - welcome to the site, i got the part #'s off of Cummins quickserve, according to the numbers, the upper engine gasket kit with a STOCK thickness gasket is P/N - 380497-01. the same set with a . 010 over headgasket is P/N - 3802364-01, and the gasket set with a . 020 over headgasket is P/N - 3802245. i got those numbers using my esn, all the parts should be the same. good luck with your project.



wes

 

[CumminsPower98]

My advice is to go with the stock gasket even when shaving the head unless you are going to be adding a lot of boost. The change in compression is so minimal you won't notice since the head is flat. The only change will be from the tiny spaces around the valves. The thicker gasket will give you harder cold starts and more smoke in the winter. . 012 came off my head and it has the stock gasket and is running just fine. You don't have to have new head bolts either. There is a gauge in the gasket set to check if they are okay for length. I have done a number of gaskets on moderately turned up engines (under 40 psi) and used the original bolts and had no trouble. Studs are also an option that will take your holding power up a ways if you don't want to go the o-ring rout. I personally run 12mm ARP studs on the stock gasket. I'm in the neighborhood of 300 RWHP and also under 40 psi boost. Studs are a bit of a chore at first as you need to re-torque them several times at first since they don't stretch as much as the stock bolts so they become loose as the new gasket settles in. My cousin 's 97 is running similar power to mine and is doing fine on the stock bolts. I went studs because I was towing for a living at the time and seeing lots of sustained high boost.

 

[Joseph Donnelly]

You will find that the new replacement head gasket, originally for marine applications will seal well with up to 60 psi of boost. In stock thickness, it is part number 3283335, which is stamped on the part in an area where the black composite material is visible. This gasket, and the . 010” thicker 3283337 and . 020” thicker 3283339, has more orange sealer embossed around water and oil passages and will seal a lot better.



You will probably find that it will take about 0. 008” off the surface to clean up the warpage near the thermostat and remove pitting near the sealing beads at the cylinders. It is critical that you choose a shop that can and will put a super fine finish on the head equivalent to OEM. You will not be able to catch or even scratch a fingernail in the finish. Very few shops can/will achieve this quality of finish. Also, you definitely should do a valve job. The intake seats will be pounded out and the exhaust pitted. At your mileage, you should consider new injectors while the head is off, and a three-piece exhaust manifold to prevent breaking ears off the head from the shrinkage of the stock manifold .

The material removed from the valve faces and seats in the head will roughly equal the amount you surfaced from the head in terms of “combustion chamber” volume, so the stock thickness head gasket will usually be fine. The valves are typically recessed about . 055” from the surface, so there is a definite change in volume from surfacing the head.

 

[FParisi]

I am just about to have the HG replaced on my '95 - leaking coolant at the thermostat housing. Is there always/usually pitting or does the HG just fail with time?

It just started leaking after new radiator installation + block backflushing by radiator shop.

I was debating getting the 3 piece exhaust manifold - do the stock manifolds always shrink? Would the 3 piece help much with EGT?

Thanks

Frank

 

[Joseph Donnelly]

There will usually be pitting around the sealing beads (“Fire rings”) at the perimeter of each cylinder. There will be rust/pitting/deposits elsewhere on the head and block, but usually not to a critical level on the block. Every 12-valve single piece, stock exhaust manifold that I have inspected was shrunk to some degree. Almost every one was shrunk enough to warrant replacement. With stock power or moderate power increases the benefit of the 3-piece exhaust manifold are durability and protection of the mounting bolts and the ears of the head from breakage. Do not look for some significant lowering of egt. The biggest exhaust restriction is the exhaust (turbine) housing of the turbocharger.

 

[Forrest Nearing]

yup, saw a truck today that was about to lose the #1 exhaust ear off the head because of manifold warpage!

 

[FParisi]

Thanks for the replies guys

Frank!

 

[SRehberg]

I read where it is suggested to shave the head when replacing the head gasket. At the risk of sounding ignorant, why? Reason being, doesn't everything warp together? If the block matches the head then it seems to me putting a perfectly flat head on a less than flat block increases the chance of leaks. Now I can see it if the gasket only warps and not the block.



Thanks

 

[GAmes]

I too had a small leak at about 195k. I respect Joe's knowledge, he has worked on my truck, but your problem may not be that bad. First off, I was losing about a pint of coolant every 2000 miles or so. I had a Cummins mech look at it in Oregon. He advised me that it was a common problem, that the leak was external and not to worry about it. I did worry about it, it bugged me. When I got back to TX I bought a head gasket kit from Cummins and pulled the head. There was no water in the cylinders. I put a straight edge on the head and could see no warpage. I put 60 lb springs on the intakes (already had them on the exhaust for my EB) and replaced the valve seals because they came with the kit. All the exhaust manifold bolts started easily by finger, so it wasn't warped or shrunk. I replaced the head gasket and bolted the head down using the specs from my Dodge manual. Nearly 350k later I haven't had any more problems, and I'm still running the original stock injectors. My advice is to look to see what the damage is before buying a bunch of parts.