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Discussion Starter · #1 ·
I was replacing the intake and exhaust manifold gasket on my 2.5L 97' TJ after seeing bubbles seeping out from the manifold around the front exhaust port. It also has a pretty rough idle for the first ::20 seconds after a cold start and then runs fine. Replaced the gasket once before and it seemed to help. Any way, I got the intake and exhaust manifold pulled away slightly from the engine to replace the gasket and was able to see inside each exhaust and intake port. The front exhaust port valve you can see a little bit of green coolant pooled on top of the valve (and this valve only).

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I should note that I did not drain the coolant before I started. I never thought about it since no coolant lines needed to be disconnected and no coolant channels where ever exposed however looking back at the service manual it has you "drain the coolant" just to replace the gasket. Is that why I'm seeing coolant or is there something more serious that I need to investigate? 110k miles on engine. Never any oil in coolant or visa versa. Doesn't burn oil or lose coolant that I've noticed. Anyone have any experience with this.
 

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As far as I know there's only one way coolant can get there and I'm sure you don't want to hear this but you probably have a cracked head or I'm not sure but I think the valve guide runs through the coolant passage. Either way the head needs to come off.
 

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Discussion Starter · #3 ·
Roger that. Would there be any reason or way I could do a compression test or slightly pressurize the coolant system and see if it leaks? Or just pull the head and go from there?
 

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Roger that. Would there be any reason or way I could do a compression test or slightly pressurize the coolant system and see if it leaks? Or just pull the head and go from there?
Yeah you could preasure check the cooling system, I think you said that you didn't open up the cooling system yet. You should be able to look in that port and see the coolant trickleing in from the crack if it is cracked or from around the valve guide.
 

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Also if you pull your plugs you should be able to see the difference in that one plug if it's been burning coolant for a while.
 

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Discussion Starter · #6 ·
I've never pressure tested a coolant system before. I'm guessing that I would remove the radiator cap and hook up a water hose just like flushing but closed system? My well pressure only runs at about 42psi if that's going to be enough. Thanks for help by the way!
 

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A hand pump device with a radiator cap on it is connected to your radiator and pumped up to about 15 -20 psi then you let it sit and see if it drops or maintains pressure.
 

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Discussion Starter · #9 ·
Pressure tested the cooling system. Held pressure. Spark plugs all looked normal. Took the head into a shop. Cracked in two places around inside of number 1 exhaust port. New head on order. Thanks again for the help guys.
 

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Discussion Starter · #10 ·
I'm in the process of reinstalling the timing cover. The bottom seal from oil pan to timing chain cover is not making sense to me. The new seal is different. Directions say to put oil on the underside of seal!? I would think everything would have to be rtvd and sealed up. I already have the new smaller seal trimmed correctly and rtved to the bottom of the cover. It fits on nice and snugg when fitted but with that bottom seal being on the front it seems like it is a vulnerable seal point right into the oil pan. Just looking for some confirmation to go ahead and apply rtv to the sides ONLY and engine oil to the bottom seal (to help lubricate it as it slides on I guess) as per directions. I'd feel better with a thin coat of sealant instead of oil though.
 

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Jonah its one of three, first. bad head gasket, second. cracked head, third. the jeep grimlins thought to play trick on you. They put some coolant on valve while you were pulling intake/exhast manifold. We will show him hehehe. I would go with one or two here.
 
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