skunker

Hey folks,
First post here. I need to flush and refill my coolant system and I want to replace the thermostat. Okay, I checked and it was a superstant 160F thermostat. I have heard that's not a good one to use...and that I should use a 195F thermostat. If so, why? I'm in south Texas...San Antonio...so the summers get frickin' hot...shouldn't I use something more like 160 or 180F?

I'm a total car newbie, so does anyone have any advice?

Thanks!

ol"blue

Fuel injected vehicles are designed to run at a specific temperature, and to achieve that the engineers specify a 195* thermostat.
And Welcome to CF.
Dan

skunker

Thanks ol'blue. Does it make any difference that I have a '90 XJ Cherokee? I'm puzzled why I found a 160F thermostat in it. Maybe a mechanic somewhere slipped it in.

ol"blue

People sometimes change to a lower temp t-stat to alleviate an overheating issue. Or because they can't fix the problem the correct way, and are trying the "cheap fix". But this doesn't take care of the problem.
The t-stat keeps coolant in the engine to draw heat away from it until it reaches 195* then opens, allowing the coolant to travel to the radiator to be cooled before traveling back to the engine. After the engine cools down the t-stat closes stopping the flow. This also keeps the coolant in the radiator longer to be cooled by the air flowing through it.
If you install a lower temp. t-stat it will hardly ever close, and this in turn won't allow the coolant to remain in the radiator long enough to sufficiently be cooled before returning to the engine, and the temp keeps rising.

skunker

Help!
I just replaced the thermostat from 160F to 195F and I am still having overheating problems! I left it running for 10mins with AC on full blast and it overheated and the coolant resorvoir lid blew off and spilled my coolant all over the place.

Any ideas what next to check? Thanks. I have a 1990 XJ

alpine.adrenaline

Burp your system and clean your radiator inside & out. Are you sure your water pump is good? I've also heard of some new thermostats being defective, the upper radiator hose should stay cool or only luke warm then get hot when the thermostat opens.

skunker

I had actually drilled 2 small holes into the thermostat thinking it would burp the air out. I don't think that worked...however...after I shut the car down, you could hear air coming out of the coolant reservoir. I left the cap off and let the car sit for 3.5 hours. I started it up again and it didn't seem to overheat this time, but I only waited 10mins and I didn't drive it.

I will try to drive it tomorrow morning. I think there was still air trapped inside. It sounds like it will be OK tomorrow. I will report back.

Thanks.

sv41878

There was a post a while back about burping the system, run a search, can't remember how it went, something about the heater on high and 2000 rpms or something.

NewJerseyXJ609

inspect your fan clutch