Need a little advice about my 88 jeep. Not showing signs of blown head gasket.?

Question

Ok so I think I narrowed it down to why my jeeps is still overheating. I replaced the thermostat and fan clutch with no luck, so here is what it is doing...I turn it on when its cold and it warms up fine. As it gets to the point of the thermostat opening up, it opens normally and keeps the temperature normal. At the same time the expansion tank that holds extra fluid completley drains into the motor and the temp. goes back down to 195 momentarely so I know the water pump is working fine. As it goes through the motor, the temp spikes again well past 210 and the water comes back into the expansion chamber boiling and steam comes out of the cap. After it cools I check the cap and the pressure almost shoots the cap off. I inspected the cap and noticed that the small rubber seal in the middle on a spring is warped and doesnt really look like it can hold a seal. So my question is, am I right...is all this mess just a faulty seal on the cap?

Answer 1

you could be right. but i would buy a whole new radiator cap. there set for a certain pressure. and caps are known to go bad. if that's not the issue which it probably is i would check your radiator. there under size in my opinion on jeeps and after they age a little or get plugged a little they don't cool the engine efficiently. good luck

Answer 2

It can be, a radiater cap has to release pressure at a given psi. I don't want to be the bearer of bad news but after doing the cap change, and looking in the radiator as it's at operating temp and seeing that the vanes are clear and flowing well, pull your plugs, if your notice that one or two of them are so clean they look steam cleaned, you may have a crack in the head next to the exhaust passage, this slowly superheats the water until the thermostat and the radiator can't keep up with it, the thing about this is you will not normally see water in the oil as with some cracks or blown gaskets as it goes out the exhaust as steam, and does not leave water dripping out the exhaust. Another way to see, is to run it until the thermostat opens and looks down into the radiator and if you see bubbles, or thick foam, this is another indication.

Answer 3

Cooling device rigidity assessments are no longer a competent attempt for head gasket leakage because of the fact combustion pressures are as much as one hundred cases as great as coolant pressures. for the reason which you're no longer having head gasket indicators i think of you're ok, yet there is an common attempt you're able to do. With the engine chilly, eliminate the rigidity cap. you do no longer point out make, form, or twelve months, yet on some autos the cap is on the radiator and there's a separate reservoir and on others the cap is on the reservoir. start up the engine, place the palm of your hand on the situation the rigidity cap replaced into, and if there's a separate reservoir pinch closed the hose between the situation your hand is and the reservoir. in case you sense gradually becoming rigidity interior of three-5 seconds the top gasket is leaking. If no longer, that's not. I even have on no account generic this easy attempt to be incorrect.

Answer 4

The warping of the resevoir cap is probaably due to the extreme heat and pressure from the hot coolant. Are you sure it isn't the head gasket? There are kits that measure the amount of fuel in the coolant and give you an idea of your head gasket's condition. Is it the Inline-6 motor? I had the same problem and it was the head gasket.

Answer 5

Uhhhh......
The expansion tank is supose to slightly fill up as the engine warms and the coolant "expands".

Next time the engine is cold, start it up, remove the radiator cap and fill the radiator untill it's full. (with the engine RUNNING)

Then fill the expansion tank half way.

JOB DONE!!

Answer 6

you could be right try a new cap, if it does not solve the problem it will definitely be the head