engine warms at idle...cools at speed.

92 Rodeo

Warms up to normal operating temp when at idle.
As soon as I get it on the highway, the temp drops (both in the gauge and the heater).
It's cold outside. My girl needs heat.

When warm outside (months ago) did the timing belt, tensioner, idler, waterpump job. Did the Thermostat at the same time.

I figured I got a bum thermo, so I replaced it last night.

No change.

I boiled both the old and new thermo and they operated identically.
they both have 170 F rating.

I am about to put some cardboard in front of the radiator.

Any thoughts???

Doesn't your Rodeo have the 3.1L engine?

If so, (according to my Haynes manual) it should have a 195 degree thermostat not a 170 degree.

But that would explain alot.

Unfortunately, the stealership (if you can beleive this) does not stock the thermostat.

So, I went to a pretty reputable foreign car parts place and they only listed one, the 170F.

The cardboard in front of the radiator trick is doing the job for the moment.

Thanks.

Considering that the 3.1L is an American engine you should be able to find a thermostat at any car parts store.