[Steve91T]

So I've been putting some miles on this engine after it sat for years and I've got a problem that I would like some help with. It's got a new water pump and thermostat, for now the heater hoses are capped off. I'm running a manual fan switch. The water temp gauge is in the drivers should side head.

So everything seems normal except for some reason if I drive down the highway my water temp will drop to about 150 degrees. It acts like the thermostats is stuck open. Yesterday I pulled the t-stat and put it in a pot of water and watched it. It started opening at 180 degrees like it should, then closed when it cooled down.

So why is this happening?

[mr.beachcomber]

Have you checked the temperature sender for accuracy? Just a thought as I haven't found anyone with a similar problem. (Even those with 160F thermostats don't see that much cooling except during the winter.)

[Steve91T]

Have you checked the temperature sender for accuracy? Just a thought as I haven't found anyone with a similar problem. (Even those with 160F thermostats don't see that much cooling except during the winter.)

Yeah back when I had a 160 thermostat it would still stay around 170-180. This 180 degree one should stay around 190. I don't get it it. I took temp readings after a drive using my temp gun. The water pump housing, and all coolant hoses were in the 130's and the cylinder head itself was about 180. That's about the temp the water temp gauge was showing.

I'm just running water, no antifreeze. Maybe I'll just pull the sender and see if I can check its accuracy. I have to add some heater core hoses anyway, so that'd be a good time to check it.

Any other ideas though how this could be happening?