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Help Coolant System, lots of failures, searched...

StuckonTheDock

NAXJA Forum User
1990 Cherokee Lorado...It all started the other day when I had a plastic fitting break and dump my coolant, no steam cloud, no smell, so I didn't find that till too late. I noticed a tiny bit of steam from the corner of the hood, and since I had a small leak at the surge tank cap, I felt I could safely disregard.

About 3 miles from home the smoke started, soon it was a trail of smoke James Bond would have been proud of. By then I was very close to home and figured that it would be impossible to restart if I pulled over then. So with a quiet, yet fervent prayer, I continued to blaze my way home. She died in my driveway. I coasted on a cloud of smoke into my parking spot.

I opened the hood, and to my supprise there was no fire, but smoke WOW! She sat and hissed and smoked popped and pinged for almost 2 hours. When the show was over, the head was sparkling clean, not a drop of sludge left.

To my supprise, after filling with water again, she started right up, although she has a new exhaust leak at the manifold.

Well, the temp guage hasn't worked since I got her, so that is problem #1, the second is that I am sure that I haven't been able to get all the air out of the system. I had to replace a heater hose and the overflow bottle, when I fill the system, the radiator hose on the passanger side feels full of air not water. Also the electric fan NEVER comes on.

So, in the end, I suppose what I need to know is what typically causes temp gauges to quit (not the fuse). How to burp the system. What I should check on the electric fan. I replaced the sender below the tranny hard line on the radiator, to no noticable effect, other than that, I am stumped. I do have two "donor" vehicles for parts. TIA!!
 
On my '88 There was a coolant temperature sensor on the top of the motor near the firewall. I think it had a small electrical sensor on it. What you need to do is park on an incline so that sensor is the highest point on the motor and remove the sensor slowly and not all the way. Once it stops hissing air you should tighten the sensor and crank the motor a few times. Repeat the bleed as many times as you need to, until not a lot of air comes out.

I had to do this many times until the thermostat kicked in, then the fan came back on.

I hope this helps and is accurate. I did this years ago.

You can also apply power to the electrical connector on the fan to make sure it will still works.
 
i have had great success burping the system by removing the temp sender from the cyl head while filling the system until a steady stream of coolant comes out. then installing the sender very loosely, starting the vehicle, and continuing to let the air burp out around the threads until the stat opens and you get that steady stream of coolant again. tighten the sender snugly and you should be done. it's worked perfectly for me every single time. another good tip: if/when you have the t-stat out, make sure the little jiggle pin is at the 12 o'clock position upon installation. if there's no jiggle pin, drill two small holes on opposite sides of the stat flange, and install it with them at 6 and 12 o'clock. a quick way to test the fan: unplug the connecter at the fan switch and jumper it with a piece of wire. if it comes on, then the issue would be with the switch. if it doesn't, check for power at the relay, and/or at the motor. if you've got power up to the motor, but no action, the motor's probably toast. hope this helps...
 
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