Do I need a new thermostat? (5.9L) - JeepForum.com
 
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post #1 of 11 Old 11-14-2013, 01:30 PM Thread Starter
leftfield6
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Do I need a new thermostat? (5.9L)

So, cooler weather is upon us, and I realize my 5.9Limited takes quite a while to make some dang heat.

Think I may need a new thermostat. This pic shows where my temp gauge sits after about an hour of interstate driving. Sorry for the fuzzy, but I'm snapping a damn pic at 70MPH, as you can see.



That's too low isn't it? Ambient temp that day was mid-50s or so.


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post #2 of 11 Old 11-14-2013, 01:41 PM
RWC
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Could be a bad sending unit too.
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post #3 of 11 Old 11-14-2013, 02:37 PM
StPaul59
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Almost looks like you have a 180 stat in there.
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post #4 of 11 Old 11-14-2013, 03:27 PM
riot1987
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Could be a thermo. Pull it out, put it in some boiling water and check to see if its opening up or not. Get a 195* one if you decide to replace it

http://www.jeepforum.com/forum/f22/riots-97-grand-1436100/

Build thread^^
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post #5 of 11 Old 11-14-2013, 04:46 PM
pageman
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the old boil test is ok but if you went through the trouble of taking it out just replace it since its a whole 7 bucks.mine drives at that temp all the time too so your not alone
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post #6 of 11 Old 11-14-2013, 04:51 PM
PolkaPower
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Looks like it's stuck open. That happened to me when I was using a POS Failsafe. I replaced it with a stock Mopar T stat. The difference in quality when the two are side by side is obvious.
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post #7 of 11 Old 11-14-2013, 06:04 PM Thread Starter
leftfield6
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Yeah, I think that's the weekend project. Just replacing it. I'm going to the dealer to get an OEM one, too many bad units from the FLAPs

Jeepless for now, probably not for long


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98 Grand Cherokee Laredo
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post #8 of 11 Old 11-14-2013, 06:44 PM
Gearhead31
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mine isn't wanting to get above ~130, gonna replace mine tomorrow morning.. Not sure if you have a 180 therm, yours is shot or if it's something else. If you're willing to put in about $10-12 for quality parts and half an hr of work, go ahead and replace it. With that little cost, it wouldn't be much of a loss if it turns out it's something else and it gives you a definitive answer. Be sure to have two gallons of antifreeze to throw into it afterwards though!

1995 ZJ ltd, 4.0 i6, *cough stock cough* 253,xxx and still pumping strong
1998 Chevy Cheyenne K1500, 5.7L Vortec, mostly stock
*In peace, sons bury their fathers. In war, fathers bury their sons. - Herodotus
Quote:
Originally Posted by JasonStebbins
We can call it the Whoosh King Catalog System. :D
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post #9 of 11 Old 11-14-2013, 06:55 PM
steve_up
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Flush your heater core as well if possible. I second replacing the tstat, they're cheap and fail.
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post #10 of 11 Old 11-15-2013, 05:42 PM Thread Starter
leftfield6
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Okay, it was the thermostat. I went by the Mopar dealer, picked up an OEM thermostat for about $15 with gasket. Super easy R&R. Lost about a 1/2 gallon of coolant, most of which somehow managed to miss the basin I had placed underneath. Kitty litter took care of that. Don't have a cat, but I do have old vehicles, so kitty litter is always in the garage.

Replaced coolant, fired her up and went for a drive. Gauge moved up MUCH faster than before. I had heat coming from the vents in about half the time, a marked improvement from before. Gauge reached what looks like 190* to 200* and stayed right there.

About 20 bucks and about 45 minutes, some of which was spillage clean-up. GTG.

Thanks all.

Jeepless for now, probably not for long


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98 Grand Cherokee Limited 5.9
98 Grand Cherokee Laredo
77 CJ-5
75 CJ-5
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post #11 of 11 Old 11-15-2013, 08:43 PM
Gearhead31
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Glad you got it fixed!

1995 ZJ ltd, 4.0 i6, *cough stock cough* 253,xxx and still pumping strong
1998 Chevy Cheyenne K1500, 5.7L Vortec, mostly stock
*In peace, sons bury their fathers. In war, fathers bury their sons. - Herodotus
Quote:
Originally Posted by JasonStebbins
We can call it the Whoosh King Catalog System. :D
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