Jakesjeepmj1988 Posted August 17, 2012 Share Posted August 17, 2012 hey guys i have a 88mj 4.0l and it runs so hot after driving on the road for like 10 mins or more the hood is so hot sometimes i can't even open it with my hands i pay attention to my water level its always full it has boiled over on me twice i thought it was my electric fan not working but i found out it does i just replaced my fan clutch so now both fans are working and that didnt fix anything its still hot. so what are my options ps. i still have the dummy light dash and the light has never come on Link to comment Share on other sites More sharing options...
mvusse Posted August 17, 2012 Share Posted August 17, 2012 Without a gauge makes it harder to diagnose. If it gets too hot putting around town or idling in your driveway but fine on the highway it's an airflow problem. If it is fine idling in your driveway but get too hot on the highway it's a coolant flow problem. Link to comment Share on other sites More sharing options...
Jakesjeepmj1988 Posted August 17, 2012 Author Share Posted August 17, 2012 so if its a airflow problem what do i fix and if its a coolant problem what do i fix i just want to know all my options i will do all of them if thats what i have to do but i know for a fact when idleing and doing putting through so easy trails it when it really heats up Link to comment Share on other sites More sharing options...
cruiser54 Posted August 17, 2012 Share Posted August 17, 2012 Good chance the radiator is not up to snuff. How old is it? Ever have it rodded out? Have you ever considered using punctuation in your posts to reduce the fatigue it causes us old guys when we read them? Link to comment Share on other sites More sharing options...
Eagle Posted August 17, 2012 Share Posted August 17, 2012 so if its a airflow problem what do i fix and if its a coolant problem what do i fix i just want to know all my options i will do all of them if thats what i have to do but i know for a fact when idleing and doing putting through so easy trails it when it really heats up There isn't much point to doing anything until you know what the cause of the problem is. It's an '88 4.0L, so it should have the plastic coolant tank on the firewall (passenger side). If it's boiling over, that's where it will boil out. Is the tank cracked? Does the cap hold pressure? That tank isn't an "overflow" tank on the '88s -- it is part of the pressurized system, and if the plastic cap won't seal to the plastic tank -- the system won't hold pressure and that's often a cause of overheating. Check that first. Do not judge by how hot the hood gets. The hood on my '88 gets too hot to open without risk of burns on a summer day, and my cooling system works fine. Same is true for my wife's 2000 XJ and my 2000 XJ. So I don't consider that to be even a symptom of a problem, but obviously boiling over IS a symptom of a problem. You may need a radiator, and if it's the original radiator in an '88 with idiot lights I would almost bet that ultimately you'll be buying a radiator. But -- check out the pressure bottle first. Link to comment Share on other sites More sharing options...
Jakesjeepmj1988 Posted August 17, 2012 Author Share Posted August 17, 2012 yes it does hold pressure and yes it is the original radiator. also sorry about puncuation i an a F- in english class is there a way to check the radiator Link to comment Share on other sites More sharing options...
Eagle Posted August 17, 2012 Share Posted August 17, 2012 yes it does hold pressure and yes it is the original radiator. also sorry about puncuation i an a F- in english classis there a way to check the radiator If it's boiling over, how do you know it holds pressure? I don't know any way to test those plastic caps. Another thought: How full are you filling that bottle? It should be filled halfway when cold. Because there is no expansion bottle, it needs that air space at the top for coolant expansion. If you have been filling the plastic bottle to the top, that's whay it has been boiling over. The only effective way to test a radiator is to remove it from the vehicle and take it to a radiator shop to be pressure and flow tested. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 17, 2012 Share Posted August 17, 2012 yes it does hold pressure and yes it is the original radiator. also sorry about puncuation i an a F- in english classis there a way to check the radiator If it's boiling over, how do you know it holds pressure? I don't know any way to test those plastic caps. I ordered an adapter for my pressure tester to fit on the bottle 2 days ago. Costs $44. Got one on ebay for $28 delivered.There was one for the caps, too but I didn't bother checking the price, knowing it would probably be in the same range. Link to comment Share on other sites More sharing options...
Jakesjeepmj1988 Posted August 17, 2012 Author Share Posted August 17, 2012 i know it holds pressure because the one time it was really hot i don't know why but i decided i was going to take the cap off and all the hot pressurized air and steam came flying out so i learned from that misstake and burnt my hand a little ooops Link to comment Share on other sites More sharing options...
Eagle Posted August 18, 2012 Share Posted August 18, 2012 i know it holds pressure because the one time it was really hot i don't know why but i decided i was going to take the cap off and all the hot pressurized air and steam came flying out so i learned from that misstake and burnt my hand a little ooops Okay, then on to my next question: Are you over-filling the plastic bottle? Link to comment Share on other sites More sharing options...
Jakesjeepmj1988 Posted August 20, 2012 Author Share Posted August 20, 2012 No the water level is about half full Link to comment Share on other sites More sharing options...
Eagle Posted August 20, 2012 Share Posted August 20, 2012 No the water level is about half full I guess it's time for a radiator. The old one doesn't owe you anything -- my '88 XJ is on its third radiator. Link to comment Share on other sites More sharing options...
Jakesjeepmj1988 Posted August 20, 2012 Author Share Posted August 20, 2012 Ya thats what I'm thinking. All metal one i think what about you? Link to comment Share on other sites More sharing options...
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