Coolant in the oil, but head gasket ok?

For those that don't want to read the narrative: Had classic head gasket failure symptoms, coolant in the oil, ice cold air out of the heater, overheating problems. Pulled the head, head gasket AND head appear fine. Read on for more info.

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Alright. General coolant system nightmare. 99 Cherokee, currently 150K on the 4.0, AW4 automatic.

On the heels of the LAST oddball problem this truck had (AW4 cracking in half at the range sensor) now I've had an apparent head gasket failure, but now that its torn down, the head gasket is not, in fact, blown. At least not obviously.

When I got this truck last year, it's safe to say it had not been properly maintained. Naturally, since it was running and driving fine I didn't do my due diligence and check and replace the frequent offenders.

Started having mild overheating problems and discovered that instead of coolant, my motor was trying to run on what appeared to be mud. I flushed the system as best I could with the prestone flush kit, filled it back up with coolant and it was fine. For about two months.

So, most recently, the failure manifested itself as a detonated lower radiator hose, discovered that the water pump had one fin on it, and I did everything EXCEPT replace the radiator, because I couldn't get one locally at the time. This was when I was home for Christmas.

When I got back home, I had a radiator shop power flush it, and he said he couldn't believe how much sediment and corrosion was in the system. Doesn't know how the radiator didn't blow out. But he got it flushed out, and said to give it a try, but he wasn't holding out a lot of hope.

That was two weeks ago. The other night, driving home I had no hot air out of the heater. Then it started to warm up. Mild overheat, then cool back down. Then a few miles later, another overheat, then it cools back down. Then a mile later, it overheated hard, right on the peg. I was a mile from the house, so I beat feet for home. When I got home, no coolant hitting the ground or any problems. But I was suspecting head gasket problems.

Came out the next morning and checked the oil, and magically had acquired three extra quarts of very thin looking liquid. Yup, that does it. It's cold as hell here, so I limped it to work and called my buddy at his shop to see if he can get it in to look at it and had it towed over.

Got the head off last night.... and the head gasket is fine. At least it appears so. Can't figure it out. Either the head has a pile of tiny cracks in it, or the block is cracked somewhere. That's what I'm leaning toward.

Head is going out to be checked today. We'll see if that's the issue. Otherwise, we'll be swapping in my spare engine this week.

Anyone have any ideas? Something I haven't thought of?

Boots

You might not be able to see where the gasket was leaking.

I agree with Talyn, and until you actually have the block checked for cracks with a dye, you can't say that there isn't a problem with it.

Ditto on checking the block and head for cracks. When I first got my 88XJ I chased a random overheating problem for awhile. I had it pressure tested and it tested fine. Then one hot day I accelerated and looked into my rear mirror and saw a momentary puff of white smoke (i.e. steam) from the exhaust. Apparently what was happening was under normal driving conditions, the gasket was sealing properly. Then under acceleration and a hot day, the head would lift slightly and leak coolant into the combustion chamber and I'd see the momentary puff of white smoke in the exhaust. Solution was to have the head pulled, re-surfaced, and re-installed with a good head gasket. Also, I now periodically re-torque my head bolts to keep everything tight.

Another thing I do before re-installing a head is to clean all the surfaces with lacquer thinner until a paper towel is clean after wiping. Then, regardless of what coating is on the head gasket, I paint the surfaces of the block, head and gasket with about 3 coats of aluminum paint. That's an old hot-rodder's trick that seals everything really well.

Best regards,

CJR

I 2nd checking the head AND the block. We blew out the head gasket on my 22rte motor and it was clearly blown (White smoke, stumbling etc..) and when we pulled the head there was no signs of it blowing. But the head gasket was 'peeled' back in between the cylinders.

New head gasket and all was good. But we did double check the block/head for warpage.

CJR said:

Also, I now periodically re-torque my head bolts to keep everything tight.

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Do you notice them moving much? The only thing i would be concerned about is breaking the thread sealant on the #11 bolt.

Another thing I do before re-installing a head is to clean all the surfaces with lacquer thinner until a paper towel is clean after wiping.

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I do the same, but use brake cleaner.

I have had run-ins with chipped exhaust valves causing a blow-torch effect burning a hole into the water jacket of the head and sending the coolant out the exhaust. You might be having something similar. The other possibility is the block being cracked near the freeze plugs considering the amount of sediment that you mentioned from the radiator shop. The freeze plugs are close to the cam journals and could be a potential contamination source.

That can happen.. as well as a break in the gasket between cylinders which can the head and/or block. But that should be pretty easy to see.

Talyn,

I use a non-hardening sealant on the bolt threads, so it stays pliable and hasn't caused any leakage problems around the bolt threads when I re-torque the head. Re: head/block/gasket surface cleaning. As long as the surfaces are spotless after cleaning and a dry paper towel stays clean after wiping the surfaces-you're good. Then the aluminum paint gets into the cast iron pores and adheres to the surfaces well but the aluminum paint still allows the slight thermal expansion/movement of the head gasket during heat-up and cool-down. If the head gasket becomes "glued" to the surfaces, the normal occurring cyclic thermal expansions/movements will eventually tear the head gasket and leaks will result. The olde hot-rodders knew what they were doing!

Best regards,

CJR

I wouldn't use the paint with modern MLS gaskets. The old hot rodders may have known what they were doing, but they didn't have MLS gaskets back them. Unless the gasket calls for some form or coating, I would leave it bare.

Talyn,

We'll have to agree to disagree on applying paint to some type gaskets. I routinely paint all my gaskets and never look back.

Best regards,

CJR

The reason paint was used back in the day was because machining processes used to deck a block and to mill heads were very crude compaired to today. Multi layered metal heads gaskets were also the norm.

The machine marks left by the tooling was rough at about 125 micro-inches. The standard is 32 micro-inches today. The larger the number, the rougher the surface.

Paint was used as a poor mans sealer to fill irregularities in these surfaces. Todays gaskets are composit/steel/silicon which seal much better and have a longer life.

However, steel sealing head gaskets are still used in a lot of high compression HO engines due to that they can be reused a few times if your block and head are prepared correctly and studs are used in stead of head bolts.

Drag racers and NASCAR have been doing it this way for decades. Unless you have a high dollar, heavily modified stroker, just buy a new head gasket and call it a day.

CJR said:

Talyn,

We'll have to agree to disagree on applying paint to some type gaskets. I routinely paint all my gaskets and never look back.

Best regards,

CJR

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There is no agreeing to disagree, it is just plain wrong.

Talyn said:

There is no agreeing to disagree, it is just plain wrong.

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LOL, ROTFLMAO!!!

:yelclap:

Ah, let's see if I can comprehend all these complicated statements;

Paint was used as a poor mans sealer to fill irregularities in these surfaces.

I seem to recall very clearly buying many Ford gaskets that were coated with aluminum paint. So let's include Ford in that "poor man's" group. Likewise, aluminum paint to seal heads, was used regularly by racers who raced for money. And of course there's the late Smokey Yunick, a racer, who used to recommend "good old aluminum paint" until good sealants finally came along. Likewise, I bet Smokey was putting the best surface finish on his block and heads that was possible. But eventhough GM contracted Smokey to do research, etc., hey, what did Smokey know? Today, there are many money racers now using solid copper gaskets instead of all the "super-duper" marketed multi-layer proprietary coated wonder gaskets. I wonder why that's the case? Could it perchance be, multi-layer gasket failures and DNF which resulted in no prize money?

And the statement; There is no agreeing to disagree, it is just plain wrong.

Well before we trot out all our engineering credentials, achievements, international awards,and experiences may I ask what is your basis for pontificating that something is "wrong"? Please spare me the response, "it's the latest state-of-the art and therefore it's good". This humble servant is always willing to learn new things and I eagerly await my forthcoming illuminating education.

Best regards,

CJR

CJR said:

I seem to recall very clearly buying many Ford gaskets that were coated with aluminum paint. So let's include Ford in that "poor man's" group. Likewise, aluminum paint to seal heads, was used regularly by racers who raced for money. And of course there's the late Smokey Yunick, a racer, who used to recommend "good old aluminum paint" until good sealants finally came along. Likewise, I bet Smokey was putting the best surface finish on his block and heads that was possible. But eventhough GM contracted Smokey to do research, etc., hey, what did Smokey know?

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You are referencing old style & racing which is not what we are working on. He isn't pushing high levels of boost nor running some high compression number. I doubt he will go out and purchase a custom Cometic or SCE gasket. Even the Cometic gaskets are coated with a sealer and are installed dry.

Today, there are many money racers now using solid copper gaskets instead of all the "super-duper" marketed multi-layer proprietary coated wonder gaskets. I wonder why that's the case? Could it perchance be, multi-layer gasket failures and DNF which resulted in no prize money?

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Actually its trending toward more use of the MLS gaskets than the cooper gaskets. MLS are easier to use, no leaks, and no o-rings (although there are cooper gaskets that include o-rings in the gasket). There are still cases where a cooper gasket is called for, but there are many more situations where a MLS is replacing cooper. Not only that but you are referencing information that is old. I never said that paint was never used nor that it wasn't effective on old style gaskets or cooper. I am talking about this case and modern/ regular gaskets.

Well before we trot out all our engineering credentials, achievements, international awards,and experiences may I ask what is your basis for pontificating that something is "wrong"? Please spare me the response, "it's the latest state-of-the art and therefore it's good". This humble servant is always willing to learn new things and I eagerly await my forthcoming illuminating education.

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I'll take the gasket maker's word for it as well as the experience of other using MLS gaskets and my own experience. There is 100% no reason to coat/spray/what ever the block or head with some crap to get a good seal using a MLS on this engine. All of the MLS gaskets for this engine have sealers already impregnated in them, not just a few bare steel shims. I don't know why people have to take a gasket like the Felpros with all the research that went into them & spray crap on them they do not need.

Popcorn, peanuts, right here....LOL.:roflmao:

I am enjoying the debate

And hell, I might even learn me something, LOL.

FWIW, I have leaned more towards not coating gaskets with anything, but that said I have done some fancy gasket coating of my head gasket and the exhaust gaskets in recent years, with no problems. I did it on the exhaust because I needed a little extra due to a not quite perfect manifold surface (issues with flatness and parallelism.

I have coated exhaust gaskets in the past with cooper RTV due to imperfections in the surface and flatness issues like you stated. Its not quite as a crucial seal there though.

Talyn said:

I have coated exhaust gaskets in the past with cooper RTV due to imperfections in the surface and flatness issues like you stated. Its not quite as a crucial seal there though.

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yep, it was copper RTV I used. I also used some thin copper shims on it, on the inner two ports, and not the outer 2 ports. Worked like a champ!!!

And yes, the seal on the manifolds is under far less pressure than the head!!!! Hell the radiator sees more pressure than the exhaust.