-   ZJ Grand Cherokee Forum (
-   -   Do I need a new thermostat? (5.9L) (

leftfield6 11-14-2013 02:30 PM

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.

RWC 11-14-2013 02:41 PM

Could be a bad sending unit too.

StPaul59 11-14-2013 03:37 PM

Almost looks like you have a 180 stat in there.

riot1987 11-14-2013 04:27 PM

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

pageman 11-14-2013 05:46 PM

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

PolkaPower 11-14-2013 05:51 PM

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.

leftfield6 11-14-2013 07:04 PM

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

Gearhead31 11-14-2013 07:44 PM

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!

steve_up 11-14-2013 07:55 PM

Flush your heater core as well if possible. I second replacing the tstat, they're cheap and fail.

leftfield6 11-15-2013 06:42 PM

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. :cheers2:

Gearhead31 11-15-2013 09:43 PM

Glad you got it fixed!

The time now is 05:37 AM.

Powered by vBulletin Version 3.8.8
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.