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radiator replacement on 1990

85xjwoody

85xjwoody

NAXJA Forum User
Location
Little Suamico Wi.
Ok, just replaced the radiator and thermostat in my 90 with the 4.0 and closed cooling system. I think I have most of the air out out of the engine but I still hear alot of air in the radiator when I squeeze the upper and lower radiator hoses.
I tried filling the radiator from the upper hose and got just under half a gallon in it before it would not let anymore in.
Drilled the holes in the thermostat for burping and took out the sensor for the air to get out.
I cannot get anymore fluid into the radiator! For some reason it the fluid won't flow through the radiator but the upper hose gets hot and the bottom get luke warm at best.
Am I missing something here? I have replaced numerous radiators on the open systems but this is my first on the closed.
Any thoughts? Thanks.

Kim
 
I never had a problem in my 88.... just filled at the pressure tank while running, drove around until the air worked its way to the pressure tank, topped off and drove some more and repeat... By the second top off, it was always fine.
 
I filled the tank while running and once it got to normal temp it started to rise. Put the cap on, drove it around for about twenty minutes and came home. Checked the level and it was the same.
Took another ride and still the same. Let it get back to a cold temp and still the same level. I just don't understand why I still have air in the radiator.
 
xjboy said:
Try "burping" it by slowly loosening the coolant sending unit air should escape and once coolant comes out you should have the majority out.
Click to expand...

Did this twice. First time lots of air and second time just coolant.
 
Maybe you did get all the air out then... I don't have fluid sitting in my upper hose at all times either... I don't think you should...
 
I drained over 1.5 gallons and only put in less than a half gallon. The radiator has to hold more than that. :dunno:
 
There is still air in the radiator but my temperature doesn't go over 170. There is no pressure on the upper or lower hoses and the lower hose still doesn't get warm.
I have let it run for almost an hour and still the temperature stayed low and the coolant level stayed the same. I took the cap off and the level came up and still nothing.
 
At the very back of the head on the drivers side is the sensor for your temp gauge. Point the nose of the Jeep down hill, and with the engine cold, remove the sensor. Fill up the cooling system at the bottle until you get coolant out of that hole. Put the sensor back in and top it off. Works every time.
 
I have done this four times now and still have coolant coming out. The air is out of the engine, I need it gone from the radiator.
I finally have pressure to both upper and lower hoses but still cool to the touch on the lower hose.
Temerature is sitting at 175 now and won't go higher.:dunno:
 
That's why you couldn't get all the air out... Now after you fix the pump your good for years of fun..... Or till you drive it once.. God i love jeeps
 
But what I don't get is that everything was working normal until I decided to replace the radiator this morning because of a minor leak. Pump worked then, why not an hour later?:smsoap:
It is still working at this point I believe, but it is starting to make the good old squeeling noise so it will be replaced tomorrow.
 
Personally, I like it when they break down in the driveway and not on the trail or on the highway when its 15 degrees and blowing snow!

You got lucky, your Jeep cut you a break this time!
 
85xjwoody said:
But what I don't get is that everything was working normal until I decided to replace the radiator this morning because of a minor leak. Pump worked then, why not an hour later?:smsoap:
It is still working at this point I believe, but it is starting to make the good old squeeling noise so it will be replaced tomorrow.
Click to expand...

Can't really say. My 88 is still closed and I replaced the rad with a 2 core, all metal one. Burping does require patience. I did mine like some of the others suggest. Fill 'er up, drive around like a madman, let it cool, top it off. Repeat as needed (usually only once or twice more).
 
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