Running cold....when hot... -
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Unread 02-05-2006, 03:14 PM   #1
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1999 TJ Wrangler 
Join Date: Oct 2005
Location: , Florida
Posts: 1,419
Running cold....when hot...

'99 2.5L 60,800 miles

I had a wildly fluctuating temp gauge yesterday, I'd be driving around for....hours and it'd only be at 110 degrees, then shoot up to 1/4 of the way, then back down to 100. It even varied with turns and braking!

Took apart the t-stat housing and noticed the gasket was put in backwards (gasket on the engine, not on the housing).

Fixed it and put in a new 195* t-stat.

I drove it around and it was PERFECT. I can't emphasize how much better it drove. Idled smoothly, more power. Awesome drive...but it was only on water.

Drained the radiator and filled it with 50/50 anti-freeze.

Then I was spraying something next to the jeep and accidentally got some water on the inside (near the battery/distributor) and I got a check engine light. I pulled the neg terminal and let it dry out.

Started it up and idled rough (re-learning I guess?) but my temp was no longer normal. Now it doesn't fluctuate, but it still doesn't get anywhere near 210...stays at around 180ish.

I think I have a leak in one of my heater hoses though, would this cause that? Other than that, there's nothing wrong with my cooling system.

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Unread 02-05-2006, 03:36 PM   #2
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1991 XJ Cherokee 
Join Date: Oct 2004
Location: Denver, CO
Posts: 1,184
Hmm, doesn't sound to crazy to me, I'd be happy with it really. Only down side is that it never gets to "operating temperature" so you'll lose 1-2 mpg. On mine I got a new electric fan to replace the stock electric one (ebay $65) and I built in an override switch. Now when it's in "normal" mode it still kicks in at 210 and immediately drops to like 170! I love it. On a hot day I can let it get to 220 (have the fan on "off") and then turn it on and leave it on and it'll drop to 145.
"Nitrous? So is that like viagra for your Jeep?" -mom

"I flopped it"
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