Shawn's 96

So a little back ground info; I have a 96 Cherokee with a 4.0 and last summer my wife took it to pull a tenant trailer to the coast and when she started to see if overheat, instead of pulling over she thought “ Hmm I should hurry up and get there” and floored it. Needless to say she blew the head gasket. I think it originally overheated because the electric fan stopped working. I replaced the sensor and relay but it only works when you have the defrost or A/C on so I assume the issue with the fan is in the CPU. The continued to overheat daily and I have air bubble in the radiator.
So I replaced the head gasket and though I was done, but while sitting in rush hour traffic in 40 degree weather it would start to get a little hot, which is not SOP for my the jeep. No water in the oil, I’m not losing water but I am getting air bubbles out the radiator again. Could the head be warped now?? Anything else I should look at??

RTorrez1

It is possible that you could have blown the head gasket again. But just don't rush in. One of the main causes for over heating while sitting is a bad fan clutch. Change that out. It will under $40 and you never changed it before it is a good maintenance item anyways. I am pretty much betting that is your problem. Also you might want to change out your t-stat. That should be a 195deg. it also wouldn't hurt to check out the water pump and do a good cooling system flush while you are at it. Replace the coolant with a 50/50 mix of water and antifreeze. You can also do a pressure test on the cooling system to make sure that you aren't blowing water past the head gasket. Good Luck and let us know what you find.
BTW, Welcome to the forum.

lookin2wheel

If it was run to the point that the head gasket blew out, odds are VERY good you have either a warped or cracked head. Look up "cracked head" in the search. There will be losts of info about certain years being prone to cracked heads. I believe the casting number(?) for the head is"331". Hope this helps.

Brian3676

Did you make sure the head was not warped the first time you replaced the gasket?

Shawn's 96

I little more back ground. I replaced the radiator, house and water pumpabout a year ago; I replaced the thermostat last fall when I replaced the head gasket.The clutch fan seems to be working fine, unless they can stop working while you’redriving?

The engine is a 96 and the only number on the head I could find was 630. Myradiator fluid is green, my oil is black/brown and all the cylinder pressuresare between 160-170.
At this point I guess I’ll pull the head andtake it to a machine shop

DFlintstone

Ha! What coast? 40 of what degrees?

*****. I thought I had this "canned" so now I WILL can it.


An easy three minute test for a "pretty shot" head gasket is to power-brake it with the filler cap off. It adds a level of safety if it's nosed near a tree or power pole or something. You fill the coolant up enough so you will see any bubbles in the system, (to the top). Holding the brake on solid, give it steady, moderate throttle in drive. Your test will be shorter if you have a manual, a clutch will be getten pretty hot in 10-15 seconds. If combustion gasses are going into the water jacket you might see it. (steady bubbles). If it's bad it might slam into the hood. Some surging is normal. This test won't tell you you are good, but it can be pretty clear if have a real problem.

DFlintstone

I do believe that is 0630. Our E-Fan temp switch does not come until about 218* F. Are you boiling over? Maybe you are fine? If your gauge is showing hot and it's not boiling I might suspect the sender and cross check the actual temp.

Shawn's 96

I know the E-fan isn't working properly, it'll only come on when I'm in defrost or A/C. I've replaced the sensor and the relay so I'm told that the problem is in the ECM.
I already have bubble coming out the radiator fill at ideal but I'll see if they get wores when I power brake it. I think it's time ot break out the wrenches.

tjwalker

Was the head checked for flatness/warpage and cracks when you replaced the head gasket?

Always recommended when the head comes off......