1990 Jeep over heating

GCT717

MEMBER
1990 JEEP

Hello, I have to check my coolant every week, to see if all the coolant drained out. Once, I do that, I fill the overflow with water or coolant. I use water becasue once I fill the overflow it drains into the radiator within the matter of seconds, then comes right out then I put more, that drains. When i'm done filling it up. I drive about 10blocks. Once I turn off the car I hear this rumbling loud sound comimg from my overflow tank. I lift my hood up, then all the coolant comes from the top of the over flow. I know, that the overflow cap does not fit. Could that be the problem? I changed my thermostsat, radiator, and fan, however; my a/c blows out warm air, and the a/c fan under the hood does not come on. Sohuld I just get a whole new overflow tank? Please help i'm tired of buying and putting coolant every week.

2 Replies

MIKEYBDMAN

MECHANIC
623 POSTS

Ok, your radiator should not overheat even if you have no overflow tank at all.
Here are the simple facts of a cooling system. If you have to keep adding radiator fluid, you have a leak. You must find where the leak is, and fix it to correct your problem. So, my first question is, where is the radiator fluid going when it leaks out? Do you see where the leak is?
Ok, if you see the leak, repair or replace what ever is leaking, and that should solve your problem.
If you dont see any leak, then maybe the engine is overheating and when it does so, it forces the water back out of the overflow. If this is the case, your thermostat may be stuck closed, and needed to be replaced. This is a cheap and easy fix that might solve all of your problems.
If your thermostat is not the problem, and you cannot see an obvious leak, then it is probably one of two things. Either your radiator fan is not working properly (Should cool some while you are driving without the fan on), or you have a leakinternal of the engine and the coolant is either going into your engine oil, or being burned thru the cylinders. What happens is either the head gasket is leaking or the intake manifold is leaking. You can check the head gasket by running a compression check on your cylinders and see if any or too low.
Good luck, and hopefully it is just the thermostat.