Thermostat

what tempature thermostat do you suggest running in an 89 4.0L??

195*....only one I know is available. Factory (OEM) has a hole in the top (to help it bleed)...might consider drilling a small hole in the top of non-OEM to help with the burping.

x2 on 195. Other ones do exist, and I've heard several people swear by 180, with the thought being that the lower temp trigger is a way to combat overheating. However, the concensus (as I understand it) seems to be that the 195 is better because (1) the ideal operating temp for the XJ engine is around 210, so the 180 takes longer to get to ideal operating temp every time you drive it, and especially in winter when overheating is much less of a problem, thus causing excessive wear and metal fatigue in the engine (2) the advantage of the 180 over 195 in preventing temps over 220 is very, very small or even non-existent (since all it does is to start the coolant flowing a little bit earlier, when 195 is plenty early enough to become fully effective before temps near 210).

x3.....

89cherokeexj said:

what tempature thermostat do you suggest running in an 89 4.0L??

Click to expand...

I have the 185 in mine, runs about 195 in the desert.. My MPG is the same, didn't change it at all......I would not go lower than this..I see you live in the high desert so it can get just as hot