[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?

[Steve91T]

So I hooked up the heater core, I now have heat. When topping off the system, I started the engine with the radiator cap off. Doesnt the small stream of water shooting out at the top of the filler neck come from the T stat being open? If so, mine does it when cold. Just took it for a drive and the problem is still there. Somehow water is always bypassing the T stat. Weird problem to have.

[slowTA]

Doesnt the small stream of water shooting out at the top of the filler neck come from the T stat being open? If so, mine does it when cold.

Sounds like your thermostat is stuck open or opening too soon, try a new one.

[Steve91T]

Doesnt the small stream of water shooting out at the top of the filler neck come from the T stat being open? If so, mine does it when cold.

Sounds like your thermostat is stuck open or opening too soon, try a new one.

So you should only see that stream when the T stat is open? I don't see how it's possible. I've pulled that thing out twice and it's closed and like I said, I watched it stay closed in a pot of water until 180 when it started to open.