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Decent thermostat for a 4.0?

bradleyheathhays

NAXJA Forum User
Location
Lexington, KY
'96 XJ 4.0 here. Heading down the road at a consistent 60 mph yesterday in 55F deg weather and my engine temp gauge on the dash stayed b/t 165-175 only, so it appears my thermostat is stuck open. Not the first time I've seen it dip that low after fully warming up. I believe it was a common part out of O'Reilly's maybe.



What's a decent quality and not too high priced thermostat I could get for my engine that won't be failing anytime soon?
 
I have had good luck with Murray brand T-Stats, they are made in Israel, not China or Mexico. And they are no priced liked an OEM.
 
I looked at the Stant chart, multiple part numbers for the same application. Some of the differences seem to be the corrosion coating on the thermostat, some I'm unsure of.

You also need to be careful of universal thermostats. The overall height of a universal and a XJ specific thermostat can be minor but important. I've slightly crushed a thermostat before trying to use a universal type. I'm careful now to use an XJ specific thermostat and if I have to use a universal I check the clearance really closely. Jeep parts can be scarce here, sometimes I have to use whatever I can get.

Th temp gauge on my 96 dips to around 175 on the highway (plus or minus, not sure of it's accuracy), my thermostat is new. I keep the heat at minimum on mine, even then it gets hot inside (I am kind of warm blooded I keep the drivers window cracked until it gets well below freezing outside).
 
Do not trust the dash gauge, use an OBD-II scanner or blue tooth with a cell phone app and Torque Pro to monitor the ECU/PCM temp reading from the engine temp sensor. Dash gauges on jeeps are notorious for being off.

'96 XJ 4.0 here. Heading down the road at a consistent 60 mph yesterday in 55F deg weather and my engine temp gauge on the dash stayed b/t 165-175 only, so it appears my thermostat is stuck open. Not the first time I've seen it dip that low after fully warming up. I believe it was a common part out of O'Reilly's maybe.



What's a decent quality and not too high priced thermostat I could get for my engine that won't be failing anytime soon?
 
I put a failsafe in and it failed immediately, swapped in a non-failsafe stant....same problem, won't go over 170ish. I'm seriously disappointed in the quality of parts we can get these days.
 
I ordered a Stant 195 degree thermostat from Summit Racing for my '96 4.0 2 years ago. Have had zero problems with it. In fact, I just did a coolant flush two weeks ago, cleaned it up and stuck it back in... no doubt good for another 2 years lol.
 
I've had goo luck with AC Delco. Put the little rivet/valve at the top.
 
I use the dealer ones, takes the guess work out. Maybe a Stant is $15 less every few years. You do want to change them every few years, as they can get weak, and fail open or worse, fail shut.
 
'96 XJ 4.0 here. Heading down the road at a consistent 60 mph yesterday in 55F deg weather and my engine temp gauge on the dash stayed b/t 165-175 only, so it appears my thermostat is stuck open. Not the first time I've seen it dip that low after fully warming up. I believe it was a common part out of O'Reilly's maybe.



What's a decent quality and not too high priced thermostat I could get for my engine that won't be failing anytime soon?

My '96 I used to own ran cooler too. Never really thought much about it. Heat appeared to work fine. I did replace the thermostat at some point it time with a Napa one which I believe to be a rebranded Stant. I am wondering if you are worrying about nothing. My '00 I own now, also with a Napa thermostat runs more at the 195 temp like you would think though.
 
Thanks for the OBD interface to tablet advice. Didn't know these gauges could be that far off. I'll be looking into that soon.

Since I've heard a few dismissals of Stant I'll prob go ahead and get OEM / mopar. Is there a cheaper place on the net somewhere that handles these higher quality parts? Is the local dealer the only place I should expect to find something like this locally?
 
That's a good question...what's the worry about. Mostly b/c I've watched over the last 3 months or so my average engine temp get slowly lower and more recently staying fairly low. Best guess is that it's the thermostat. For the most part my gauge seems to be acting normal.
 
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