High coolant temp after intake manifold replacement

1993 Buick Lesabre Limited 187,000 miles 3800

I replaced the plastic intake plenum and UIM and LIM gaskets.
due to a coolant leak.

plus fuel injector O-rings and also replaced the thermostat since it was out anyway and it now runs GREAT, no leaks!!

However, now the engine now runs hot. about 250, (normal is around 200 and redline is 270) thermostst is OEM 195 (same as the old one)

As an added note I also replaced both the temp sensor and the temp switch since I damaged the connectors trying to get them out. They are in the correct positions and the connectors are attached.

Could this just be an air lock in the sysytem, the wrong sensor/switch (I checked the part #'s twice and both seem and look OK)
or did i miss something altogether?

Did you put the thermostat in with the pellet end down into the engine?

Are you sure the engine is at 250?
Are the cooling fans running on high?
Does it boil when you turn it off?

Is the radiator full and did you do a final fill with the engine running with someone speeding it up to 1500 or 2000 while you filled and put the radiator cap on?

Sounds like you may have and air pocket in the system.

Did you put the thermostat in with the pellet end down into the engine?

yes it is in the correct orientation.


Are you sure the engine is at 250?

according to the gauge it is running between 240 and 250


Are the cooling fans running on high?

the fans run both high and low

Does it boil when you turn it off?

No boiling or hissing


Is the radiator full and did you do a final fill with the engine running with someone speeding it up to 1500 or 2000 while you filled and put the radiator cap on?

radiator and overflow are both full but I did not do the engine at 2000 rpm while i filled it thing you mention...

Is it possible I turned the temp sensor into far and it's contacting the metal therefore giving the temp of the manifold and not the coolant?

everything else seems to be fine except for the temp...

i'll try taking the temp sensor out a few turns and see if that makes a difference

i'll try taking the temp sensor out a few turns and see if that makes a differenceBeware, if you loosen the sensor after tightening, it will leak.

I would be suspicious of the new temperature sensors.

Do you have access to a temperature sensor gun? Do any of the box stores loan the infrared temperature sensors? I know HarborFreight has them and has various coupons in magazines and their ads. I remember wrapping a meat thermometer against the upper radiator hose and insulating with some old sock and some duct tape (of course).