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89 XJ overheating-vapor lock?

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Joined: 23 May 2007

PostPosted: Wed May 23, 2007 4:43 pm    Post subject: 89 XJ overheating-vapor lock? Reply with quote

First off, hi, and thanks for having me to the site. It's nice to be here.

As we all know, the renix system is a pita to get an air lock out of.
My wife has an 89 XJ 4.0 auto and it's overheating like a mofo.

It started with a small leak at the overflow bottle which I fixed up by double clamping the hoses. BUT the coolant level dropped enough to get air in the system when I topped up the bottle.
I've replaced the thermostat, the pump is pumping quite fine, the thermo is opening ( I can see it on the gauge when it reaches operating temp). The rad isn't plugged. I've flushed it 3 times. SOOOOOOOOOOOO the only thing that I can think of is a vapor lock. I've put the front end in the air and bled out the lines. I've put the ass end in the air and pulled the temp sensor and a bit of air burped out too.
I am sick of driving with the heat on to keep it cool, not to mention the fact that I am scared of cooking the tranny.

Any ideas would be great.
Thanks in advance.
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Brad The Best

Joined: 14 Jan 2007
Location: Kamloops B.C Canada

PostPosted: Wed May 23, 2007 6:44 pm    Post subject: Reply with quote

welcome to the site

1. you could convert to the open system .

2. i have the stupid closed system on my jeep , the best way to put coolant in is to drain it and then use the mityvac kit that creates 25lbs of vacuum in the system and sucks in the perfect amount of coolant air free .
MV4535 Cooling System AirEvac Kit is the one im speaking of , however its not very practical because i believe its over 100$ but can't remember .

3. the air should work itself out eventually , as long as you are sure nothing else is wrong with the cooling system .

4. if your worried about the tranny a transmission cooler is around 40$ and is easy to install .
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Joined: 12 Aug 2006
Location: Hinesville Ga

PostPosted: Thu May 24, 2007 4:39 pm    Post subject: Over Heating Vapor Lock Reply with quote

My 1988 XJ was converted to a an open system about 2 years ago.
That article is OK for starters but is outdated.
Go to a local auto parts store. I used Advance Auto parts.
The radiator is a two core from a 1991 XJ. The rad comes with a plug
for your coolant fan switch, no rewiring or cutting it out of the system.
Mine has a 14 inch fan instead of the fan clutch which comes on at 185
degrees and my condenser fan comes on at 206 degrees as a backup.
The factory coolant bottle is replaced by an overflow bottle for about
$10.00 from Advance Auto parts.
I have never had my temp gauge come close to 210 degrees even in
low range in 97 dgree heat. My method of purging the air out is take off the top rad hose at the T/ Stat and fill the hose until you see coolant coming out of the T/stat housing. I also blow into the hose to force the air
1988 Wagoneer Limited XJ Tellico Tested
Rocklizards panels, Tomken rear bumper and front Tow brackets, Rocket air intake, 2 inch lift,
30x950x15, 1991 coolant system with electric fans, 8,000 mile marker winch
1991 Cherokee Limited
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