I recently lucked into an '89 XJ for dirt cheap. The previous owner told me that the engine needed replacing. I jumped the dead battery and it ran just fine, until the coolant begin "boiling" over. I've read most of the forums info on this and think I have a pretty good grasp on the problem. I had a mechanic replace the fan clutch and he used a vacuum system to refill the coolant into the system. This seamed to work for about a week but then it began bubbling over and overheating. I'm worried the head gasket may be bad but when the mech used the vacuum system, we let it sit for about 5 minutes and did not notice a drop in the vacuum pressure so we assumed there were no leaks. Could the defect in the head gasket be small enough to not be noticed in a vacuum but when exhaust pressue is applied, it leaks into the cooling system? I replaced the thermostat with a Checker Auto one, but was not familiar with the breather hole and may have installed it wrong. I am going to get an OEM one and install it soon. Also, I plan on replacing the "closed" system with an "open" system. Will there still be a problem with the cooling system if there is a defect with the head gasket but I update the radiator first? This is a budget spare Jeep and I can only do a little at a time.
Thanks,
dgoxj
Thanks,
dgoxj