My car recently had the UIM Manifold replaced. They also replaced the T-Stat. Now it runs at 200* (as opposed to 180* before), but many times now it runs up to 230*! Yes, I have the A/C running a lot and it'* been in the 90'* around here, but 230*? It will go down eventually sometimes. Also, I noticed the coolant reservoir is on the low side. Any Ideas? 230* cannot be good. One good thing is that my gas mileage is a lot better than it used to be. weird

Did you make sure to get all the air out of the cooling system?

Are you continuing to lose coolant, or is the recovery bottle low but steady?

Did you replace the LIM gaskets, also?

I didn't do anything, I took it to a mechanic. I have no idea if they bled the air out. The coolant looks like it'* staying about the same level.

Burp the system using the procedure from Techinfo..

Most likely it'* only an air bubble.

That sounds exactly like what happened to me the first time I changed the thermostat and didn't bleed the system properly. Temperature shot up to 230 degrees and then migrated it'* way on down to about 200, but would eventually shoot up again. Coolant levels did not change.

I'd suggest you get that system bled properly right away. Having trapped air pockets can cause your UIM to fail again.

EDIT....beat me to it Bill.
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today i drove 40 miles, A/C on and off, and no problems! could the system have worked out the air itself?

Yes, it will in time.