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bubbling coolant

beakie

beakie

NAXJA Forum User
Location
Ontario, Canada
so I haven't had my jeep running well since I replaced the head gasket over a month back.
today after holiday travels I have it in the garage to figure out what wrong and I see the bubbling coolant that I have read about on here.
I had my head checked and decked its fine, so where does this coolant problem come from?
Could it be the block? Or more likely have I done something wrong when doing the gasket job?

Unless I can find some really good info between now and tomorrow afternoon I will be taking it into my mech, but I want to be able to tell him whats wrong so he can get right into it when I get there.

Any help is appreciated. Thanks
 
does it continually bubble? or did it stop after awhile?, if it stopped it may not be a problem, just air bubbles working their way out, if it continues then you have a problem......If you trust your machine shop, and you trust your work then you prolly have a problem in your block.
 
well I read about a test to find out if I have a leak.

I was told to take the rad cap off, and fill rad till fluid at the cap. Then with the engine running wait, and if the fluid level pulses with the engine and small bubbles occur I probably have a leak. The bubbles come from the compression from the combustion chamber, which also causes the pulsing of the fluid level.

Anyway, I trust the machinist, but I know I could have made a mistake. However I had problem before all of this which is why I did the gasket job in the first place. I am thinking maybe this is what blew my upper rad hose in the first place, and is why even after I did all this work, it still runs like crap anyway.

Well off to the mechs I guess.
 
just wondering if anyone has any new ideas on this topic?

I brought the Heep into the shop, and my buddy is working on it after hours to keep costs down. considering I had just torn it apart to do the head gasket, he doesn't want to tear it down again unless he has too. I would like to give him some other things he can check on top of the other diagnostics he's doing.

97 4.0L, just did head gasket myself. small bubbles at rad cap within seconds of startup, within a minute it is over flowing with small bubbles. Any other places a compression leak could come from?

thanks
 
Is there any external coolant leaks? If you have a cracked block or head you can block test it. Block testers can give a false positive if you have any sort of treament in your cooling system. Usually when coolant leaks into he combustion chamber white smoke is accompanied with it. If you have no white smoke I would begin to think the problem is somewhere else.
 
I would start with a pressure test of the cooling system. Look for leaks of any kind. A compression test may or may not reveal any answers, but wouldn't hurt. A cylinder leakdown test done a BDC may give an indication of the faulty cylinder. Keep us posted.
 
I would go with cylinder leakdown test to see if you still have a leaky gasket.
 
leakdown test is the test you want also you can get a kit to test you coolant for crank case gases to tell you if you head gasket is leaking
 
well these are all points I will pass on tomorrow. I know he performed a basic compression test on cyl#1 and it checked out fine, but I'll mention the leakdown test too.
talked to him this afternoon, he was having anothing look tonite, again after hours.

I appreciate the ideas, never knew of this 'leakdown' test. Hoping this will be rectified soon, missing the Jeep this time of year. Three months of the year I feel justified in spending the time and money on it that I do... and its off the road for this long.
 
Well if the compression test ends up being within spec. There will be no need for a leakdown test. A compression test verifies overall condition of the hole and a leak down is used to narrow down the problem. From there I would pressure test the cooling system and see if it holds pressure. If it doesn't hold pressure for 15-20 min, it has a leak. Perform a block test. Check your oil and see if if starting to turn into a whitish sludge or has an water in it and vice versa. The whitening only happens worse case scenario but it would be worth a try. If you do end up doing a leakdown test make sure and do it at BDC that way the entire cylinder is filled and not just the combustion chamber. If you still don't find anything and you have no external coolant leaks flowing as fast as the bubbles. I would for sure like to hear about this.
 
progress report.

so my buddy says after trying everything he could think of, he tried things again, and it turns out his compression tester was fubared, got a new one, #1 is 80psi. Pressurized the cyl and heard air escaping into the intake. Pulled the valve cover, took the rockers off to put pressure on valves and tried again, still air escaping.
Pulled the head and when holding a light behind the intake valve light can be seen.
So now I am taking the head back to the machinists, as I had him install the new stem seals on the valves. Hopefully he will repair this without cost and depending how friendly he is, I may not ask him to cover some of my costs involved.

Now after all this, I am unsure how it would affect the coolant, but either way I am looking forward to getting it put back together and running again. Just in time for me to head to Texas next Tuesday for over a month.
 
Just a thought...

What if the head gasket was upside down? Normal coolant flow is from the pump, through to the back of the block, up into the head then forward to the thermostat. If the gasket was upside down, most of the coolant flow would just go from the pump, straight up and out the thermostat. The low flow in the rear of the engine would overheat and blow the gasket.

You said he pulled the head. Any obvious signs of blown head gasket?

Light behind the valve could be from a bent valve, burned valve, or if you had new valve stem bushings installed, they were cut/installed at the wrong angle.
 
gasket was right side up, made sure it was before I installed it. TOP was facing me when I put the head on.
he said gasket looked fine, just sucks I need a new one, and new head bolts less than 2000km after I did the last one... all because the machinist may have made a mistake.
 
Did you check the block for flatness. A leaking valve wouldn't have anything to do with bubbles coming into the coolant. If your block is warped the gasket may not be compressed enough to keep combustion chamber pressures in the cylinder. It is possible, depending on the severity of the overheating. You should also have the head pressure tested. To make sure there isn't a crack somewhere that can't be seen. You might have more problems than you think.
 
Like I said, just a thought, a possibility.

As far as the machinist, you may have two issues. The valves and the deck surface.
 
when I originally started this project (the first time) I had the head decked .012" (12thousandths) He said it wasn't exactly warped, but for the cost of it, I figured it wouldn't hurt to get it back to perfect flat.

I have been worried it could be the block which is warped, really hoping its not, but I understand its a possibility. I am hoping my incompetence somehow got involved and I left a hair or drop of grease or something on the block which allowed for a leak.

Depending on his attitude (machinists) I'll either get it put back together properly, or get a 3 angle valve job done if he feels the need to make it upto me.
 
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