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89 Closed Loop Over heats

B

BobbyD433

NAXJA Forum User
Location
Montclair, California
1989 Closed Loop cooling system over heats. Thermostat and water pump has been replaced. New gaskets and sealed properly. New fan shroud and electric fan has been installed. Do any of y'all have an idea on why it overheated?
 
Thanks for the response and your right those little details are needed. This is what has happened. I had just made some changes to the XJ and was in route to the emission control test center. I drove 4 1/2 miles and the jeep over heated. And that's been the only time I've driven the vehicle. No heat indicator warning, no lights or bells sounding nothing, just seem bellowing from under the hood.
 
OK....where is the steam coming from? The overflow bottle, the radiator, a hose?

Background info?

We charge if we have to be clairvoyant.
 
Definitely air in the system. The older 4.0s are a pain to get the air out. best way is to use a mity vac or similar tool.
 
In response to the question about the events coming to the over heating. I had installed a new thermostat and new hoses 1 at a time to the water pump then the thermostat housing. Then started the XJ, and poured 50/50 coolent into the cooling bottle and watched it draw into the heater hose and into the cooling system. After that I drove the distance to smog check. At that time the XJ over heated and I lifted the hood. That's when I saw the steam had been escaped from under the bottle cap. I had poured 2 gal. of Peak 50/50 coolent in the radiator while the motor was running.
 
Why did you replace the water pump and T-Stat?

Being a Renix, closed coolant system, One high probability is that the top half of the radiator has air trapped in it. There is one easy trick to filling it, pull loose the driver's side heater hose at the T-Stat, it by passes the T-stat and lets air out of the block, then fill the coolant bottle till the block overflows. Then try again. It is the only easy way I know of that is fool proof for getting the radiator filled. Test the top and bottom of the radiator as it heats up to see if the top is as hot as the bottom.

You may have other problems, like a clogged radiator or....so we need more input.
 
I usually park it nose down on a hill and then pull the rear temp sender from the head.

Fill until it overflows. That should get all of the air out of the radiator.
The coolant bottles are also notorious for not holding pressure. So check the cap and the neck of the coolant bottle.
There's a volvo cap that fits, has a higher pressure rating and isn't a steaming pile.

If the radiator is clogged, leaking or otherwise suspected to be the culprit just swap it to the open system 91 radiator. It's just much easier to maintain.
 
87manche said:
Fill until it overflows. That should get all of the air out of the radiator.
So check the cap and the neck of the coolant bottle.
Click to expand...
This. You said you had steam escaping from the cap; I've had this happen on my '87. A new bottle and cap solved my problems. Pressure release should be at the radiator cap.
 
87manche said:
I usually park it nose down on a hill and then pull the rear temp sender from the head.
Click to expand...

On a renix? There is no rear temp sender on the head?
 
Some aftermarket thermostats are taller than OEM units, and can bind slightly when installed without proper indexing. This can result in overheating or slow warmups. OEM equipment does not suffer this consequence.

Food for thought from a Man with 57 years of wrenching experience.
 
87manche said:
there is most certainly a temp sender on the drivers side at the firewall.
Click to expand...

Hmm. memory is not what it once was, is that the one that runs the dash gauge? Been ages since I messed with one. Gave up on them ages ago, never could find new ones that worked right anymore, forgot they were even there.
 
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