for those of you in cold climates... running temp?

What temp does your XJ run at this time of year?

I'm a bit baffled, my XJ doesn't get above 165 on the freeway. I have an aftermarket digital gauge. Is this normal?

I just replaced the thermostat, but I bought a cheapie from O'reillys. Do cheap thermostats start opening earlier, thus keeping the engine too cool? Would a nicer one have a smaller "open range"? If that makes any sense. Like would a nice one start opening at 185 and become fully open at 195, and a cheap one start opening at 160 and become fully open at 195? I was thinking that could be the problem. If so, which one should I run?

OR, is this just the temp I can expect my car to run at in the winter in MN? I feel like its hurting my gas mileage.

Any/all opinions encouraged and appreciated.

decathect said:

....I bought a cheapie from O'reillys.

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Buy a good quality 195* thermostat from the dealership or NAPA. Cheap parts are cheap for a reason.

Your temp should be 210* when outdoor temps are 30*+. My 2000 runs at 190-200* at below zero temps.

Tim_MN said:

Buy a good quality 195* thermostat from the dealership or NAPA. Cheap parts are cheap for a reason.

Your temp should be 210* when outdoor temps are 30*+. My 2000 runs at 190-200* at below zero temps.

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Agree, always buy quality for critical components, event the small cheap things.

I recommend the Stant SuperStat Premium in 195 degree for the XJ 4.0

I never install anything but Stant, personal or customer vehicles.

Always post the year/engine of your XJ in your thread. It will give you the most accurate responses for your particular XJ.

How is the heat in the cab? What temp stat did you install? Should be a 195 ONLY.

Never a bad idea to get your mitts on a point and shoot infrared laser pointer thermometer (I bought a Raytek MT6 for about $45). Any shop has these as well and takes all of 15 seconds to get a reading.

Point it directly at the thermostat housing to get a pretty accurate read on the coolant temperature. That way, you'll know for SURE what temp your engine is running at as you can have error in the sending unit - to gauge circuit.

I like Jeep stats and Stant Superstats. Stay away from el-cheapo. The 4.0 normal temp. range is around 200 farenheit, give or take a bit each way.

Thats what a t-stat is for,doesn't matter where you live or what time of year it is! "Engine temp is Engine temp"!

alright, where can I get a stant?

My 2001 runs at the same temp no matter the outside temp. It's always a little bit to the left of straight up on the gauge, 210 I believe. Whether it's -10 or 90 degrees, it's consistent.

ok, well thanks for the feedback everyone. Now I know that how my car is running is not normal. Thats the confirmation I needed. I'll be buying the highest quality thermostat possible.

the thermostat I put in was a 195* stat... but apparently its just low quality and starts opening way too early. And since its cold out, when it opens early the radiator cools the coolant so well (with all the frigid winter air) that the temp just stays there. That's my theory anyway.

Make sure you get a 195 degree stat. Most shops are good about giving you OEM unless you ask for something else, but some think they know better.

The Murray T-stats from O'Reilly have worked fine in my F150. For my Jeep, I ended up with a mopar stat - has trouble with the murray and I have to drill the stants (no jiggle pin). For a few bucks more, the Mopar stat has always worked fine and came with the gasket.

how much was the mopar stat?

Stats aren't expensive. I picked up a Stant from Pepboys for like $11.

Stant premium $4.95 at rockauto.com
http://www.rockauto.com/catalog/moreinfo.php?pk=49233

When the ambient temperature is low, I am not sure how much difference a good thermostat will make on the actual engine temperature at highway speeds.

In 2007 December I worked in Des Moines IA. On the highway with the heater is on full, the engine temperature sometimes fall to 160*. I blocked half of the radiator in an attempt to keep the engine temperature up thus keeping the cabin warm and toasty.

I agree with everyone though. Start with a good quality thermostat then go from there.

joe_peters said:

I recommend the Stant SuperStat Premium in 195 degree for the XJ 4.0

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I'll second this recommendation. Replaced the OEM thermostat when it failed last July with one and the XJ sits at somewhere just left of 210degF regardless of whether it's 90degF or 9degF out. I've run them in other vehicles as well with the same level of success.

decathect said:

how much was the mopar stat?

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Last time I picked one up it was just over $12, and included the gasket.

Doesn't matter if its -20F or 90F out, my '88 runs just under the 210 mark on the guage with some minor fluctuations as it opens and closes and the OEM stat. When the Murray one stuck open, it really struggled to get warm, and when it did warm up, it would run around 150-160ish tops when it was below freezing running down the freeway. The Stants were OK too, just didn't like having to drill a small hole to replace the jiggle pin on the OEM stat for the Renix era motors. Hard enough to burp them effectively...

My XJ is always at the 205-210 mark, no matter the temp.

Replace the Tstat is you are concerned, at least it is running cold and not hot right?

I bought a stant superstat! Going in tomorrow. I'll post results. There are times when getting cheap parts is ok, times when its not. I think with a thermostat I'm starting to understand that if you want the temp to be spot on, you gotta get a nice one. I'm convinced this cheap one is just starting to open too early.

MNgopher said:

Last time I picked one up it was just over $12, and included the gasket.

Doesn't matter if its -20F or 90F out, my '88 runs just under the 210 mark on the guage with some minor fluctuations as it opens and closes and the OEM stat. When the Murray one stuck open, it really struggled to get warm, and when it did warm up, it would run around 150-160ish tops when it was below freezing running down the freeway. The Stants were OK too, just didn't like having to drill a small hole to replace the jiggle pin on the OEM stat for the Renix era motors. Hard enough to burp them effectively...

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I assume I don't have to mess with a jiggle pin? Mine's a 93.

Make sure you put the thermostat in the right way around, or it'll never open... not that I know of anyone who has done this wrong or anything.

I've had good luck with even crappy Duralast thermostats (bought one in fall 08, well before I knew anything about Jeeps, didn't need to install it then so I kept it as a spare, used it a month or two ago) but definitely go for quality, the difference between a 3 dollar part and a 12 dollar part over a 100 thousand mile lifetime is pretty silly to worry about. At least the 4.0 has the thermostat in an easy to access location, a friend's Audi A4 reportedly has it behind the timing belt cover :shocked: so it's a large project to replace instead of a 20 minute job.

decathect said:

I bought a cheapie from O'reillys.

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Which thermostat did you buy. The Murray ones we sell have a couple qualities but both run about the same price.. If you bought the p/n 3009 that is the economy(the cheapy) one. The better one is p/n 3359. Both are 195 degrees. I have never had an issue with the 3359's in either of my rigs, the 3009's are a different story. The 3009's do seem to open to soon.

Tim_MN said:

Buy a good quality 195* thermostat from the dealership or NAPA. Cheap parts are cheap for a reason.

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Whats wrong with O'Reilly stats. If you get the good one verses the economy one. Oh and I work for O'Reilly's so I am curious why you feel a stat from Napa or the dealer is better. Alot of people have had bad stats from both places out the box as well. Alot of people have brand preference as that is all they have ever used and never tried another brand but will shoot another brand down from just one person having a bad experience. But if someone has a bad experience using there favorite brand they shrug it off as just getting a bad one, why is that?? Or as the op (original poster) says that they bought the cheapie stat, verses the better one. Hence the issue, I think. In the op's defense though the parts person may have only offered one choice. I hate when my employees do that to customers. Sorry kinda went of on a tangent there. Back to post..