92 temperature cycles

If it stays in the normal range while it's cycling, what is the problem? If you are sure the Tstat has the correct temp limit, you may not have any problem at all. Sounds like it is opening and closing just like it should when the engine begins to heat up to the stat limit. My 91 typically runs on the cool end of the gauge...only rises to mid-point if I climb a long hill like yours at highway speed.

"shastapat" wrotenews: snipped-for-privacy@adelphia.com:

Sounds exactly like a big pocket of air hitting the sending unit each time.

When it's air, blooomooo! Hot! When it's coolent, blam, it's colder.

I'd take off your radiator cap, start it up and let it get to operating temp and let the water bubble out of the cap opening in surges. If it all of a sudden bubbles up (thermostat opening) and then sucks down, it's the giant air bubble. Add water when it does down, let it overflow, let it go down, add water until it's stable.

Of course, never add cold water to an engine unless it's running.

Take this opportunity to flush your cooling system and add a gal of coolent.

I also clean out my reservoir by pulse blasting it with my garden hose.

-- riki

--Those who live by the sword get shot by those who don't.