Which temp. thermostat should i get?

[Blair Williams]

I'm running my '85 2.5L XJ and it needs a new thermostat but there are several temperatures available to put in...i'm not sure which to put in. what came stock in it? 160? 180?

 

[fasty]

the OEM factory 195F thermostat.

 

[XJ91]

the OEM factory 195F thermostat.

2nd that.

 

[RichP]

2nd that.

3rd that, make sure the little hole in the flange is at the 12 O'clock position, use the OME gasket too

 

[dmillion]

You should NEVER use a 160° thermostat unless you have replaced the computer with one that is specifically programmed for lower temperatures.

 

[FrankDV1]

I just changed mine from 195 to 180. Also increased the coolant mixture to 65/35 instead of 50/50...more coolant. Also did a flush...real dirty. Always felt 210 was to hot for my '97 XJ, 4.0 inline 6. My check engine light came on after all that, but went out after 36 hours or so. Any possible problems with this mod? Thanks.

PS - the old tstat had a ball in the top of it(flange). New one doesn't...problem?

 

[Beached Bones]

The T-stat should have a ball valve or a hole in the 12 o'clock position to help get air our of the system. You can drill a small hole if it's not there.

 

[akorna]

Actually water is a better conductor of heat than antifreeze, so you will likely run cooler with 65% water, 35% antifreeze than the other way around. Agree that the themostat should have a 1/16" hole drilled. What are your operating temps now?

 

[johnnyc]

Always felt 210 was to hot for my '97 XJ, 4.0 inline 6.

The 4.0 is supposed to run at 210 degrees. That may sound high compared to other engines, but it's normal for the 4.0

 

[Jeepster4wd]

yea go with a factory 195 Tstat. I went with a 180 and switched back to stock tstat runs much beter with the factory Tstat. For best fuel economy u need it to warm up as quickly as possible.

 

[FrankDV1]

About 205 degrees. "Check Engine" light went off sooner this time...less than 15 hours after replaced water pump. Thanks for the info.

 

[Dr. Dyno]

I'm running my '85 2.5L XJ and it needs a new thermostat but there are several temperatures available to put in...i'm not sure which to put in. what came stock in it? 160? 180?

If you live in a temperate climate, go for the stock 195* t'stat.
If you live in an Arctic climate, go for the Robertshaw 205* t'stat.
If you live in a hot desert climate, go for the Robertshaw 180* t'stat.