[Dryseals]

Originally Posted by RowJ

Was willing to do that. Was going to do that, until I read this description of how to do the 'Combustion test Kit' test on the NAPA webite.......

....The vehicle should be started and at operating temperature before performing the test. Vehicles with head gasket leaks may overheat, and purge hot water and steam out of the radiator.....

Given my expansion and overheating problem, what good is that?
No way I'm removing the cap when it's overly hot! Am I missing something?
Anyone ever actually used one of these?

RJ

Does it bubble and over flow when running? Or just when you stop?

[RowJ]

Originally Posted by Dryseals

Does it bubble and over flow when running? Or just when you stop?

Yes, after warmed up and driven for 10 miles, We pulled over and checked it while ideling. Very hot...bubbling.... and overflow bottle was full. It I had the bottle at the "Full" line when cold (instead of the "Add" line") it would be shooting out of the air vent on top. From the add line it ends up 95% full.

RJ

[Dryseals]

Originally Posted by RowJ

Yes, after warmed up and driven for 10 miles, We pulled over and checked it while ideling. Very hot...bubbling.... and overflow bottle was full. It I had the bottle at the "Full" line when cold (instead of the "Add" line") it would be shooting out of the air vent on top. From the add line it ends up 95% full.

RJ

Now I say head gasket.

[Divinitous]

I had the same issue, replaced a bunch of stuff and found out that the cap was not sealing right.
Also when filling the coolant before i finish i like to rev the engine so the coolant level drops some them put the cap on. Seems to push a bit more air out.

[JB73]

How is it a cooling system still have pressure after it has sat over night? The radiator cap to the overflow would allow the release of pressure yes???? I have never had a vehicle that would hold pressure when the radiator cap was removed and it was bone cold. That part makes no sense to me....if im wrong please tell me.... unless its such a slight pressure and the cap isnt allowing it to bleed pressure off to the overflow container. Im suspecting a radiator cap being the issue here...my .02 cents.

[Cavitation]

I always thought the radiator cap was why my radiator blew up. The head gasket going was the the source.

[RowJ]

Originally Posted by Dryseals

Now I say head gasket.

Agree. Tried the original factory cap that was rust coated but had worked well for over 100,000 miles. No difference.
I'm convinced it's either gasket or a small crack in head that only opens up under load. Either way it's definately exhaust gas leaking into coolant!

RJ

[RowJ]

Pulled head yesterday. On head gasket - only one VERY small spot between #1 and #2 where fire ring was 'bulged' off the gasket material and could have allowed combustion gas into the coolant? Doubtful enough that I'm having the head fluxed to be sure no cracks.
Other problem - must have gotten too hot before I caught the problem (when lower radiator hose blew). Melted small section of top lip of #1 and #2 piston. Minor scoring on cyl. walls. While the head is off, will drop pan and replace rod bearings, pistons and rings!

Question - Any trick to getting the bottom exhaust manifold bolts tightened. They were only finger tight when we removed the manifold and I can see why. Can't get to some of them with anything but a short open ended wrench from underneath!

RJ

[Mike406]

I assure you they were tight at one time. They do tend to loosen with expansion and contraction. I did a header install and the bottom manifold bolts were reached with a gearwrench. Some from above and some from beneath. At one point I put the wrench on the bolt while my buddy cranked the handle. http://www.jeepforum.com/forum/f11/9...91/index7.html

[Guardian7]

Did you bleed the air from the head per FSM? This is an issue with the head design which the FSM makes not of and can cause erratic cooling behavior. The cap should not allow overflow until you reach the 16 psi setting but trapped air in the head can cause increased expansion and contraction.

[Mike406]

Does this apply to all Jeeps? I have a cherokee. I usually park facing uphill and fill the cap very slowly. I also drill an 1/8th inch air bleed hole in the thermostat. Just be sure to install with the hole at the top. I didn't know about bleeding the cooling system on an XJ. If I don't see a bleed bolt on the water neck then I don't consider it. But it makes sense.

[mcoh1030]

So, where do you stand with this? My 4.0 is having similar problems. Let me ask you, are you getting heat in the vehicle????

[George Dickel]

Originally Posted by RowJ

Pulled head yesterday. On head gasket - only one VERY small spot between #1 and #2 where fire ring was 'bulged' off the gasket material and could have allowed combustion gas into the coolant? Doubtful enough that I'm having the head fluxed to be sure no cracks.
Other problem - must have gotten too hot before I caught the problem (when lower radiator hose blew). Melted small section of top lip of #1 and #2 piston. Minot scoring on cyl. walls. While the head is off, will drop pan and replace rod bearings, pistons and rings!

Question - Any trick to getting the bottom exhaust manifold bolts tightened. They were only finger tight when we removed the manifold and I can see why. Can't get to some of them with anything but a short open ended wrench from underneath!

RJ

While you're there, Stroke that bad boy

As for the exhaust manifold bolts, I made lots of faces, made up new dirty words, used smaller wrenches than I wanted to, and moved from above then below and back about 12 times before I got 'em all tight. That's about the worst job you can perform on a Jeep straight 6 best I can tell.

[RowJ]

Originally Posted by mcoh1030

So, where do you stand with this? My 4.0 is having similar problems. Let me ask you, are you getting heat in the vehicle????

Heat in vehicle? If you mean from heater ducts.....No. Well...yes, when turned on!
Just got high coolant temps and exhaust in the coolant.

Ordering pistons, rings, etc and dropped head off for Magna Flux, to be sure it's not cracked..... but it's several towns awayl not picked it up yet.

RJ

[RowJ]

Originally Posted by George Dickel

As for the exhaust manifold bolts....... That's about the worst job you can perform on a Jeep straight 6 best I can tell.

Which manifold? My real question is are any of the after market manifolds easier to install?

RJ