1989 omc 4.3l temp is not steady

[phillyc1]

Folks,
I had a new engine installed this season and decided to install a new San Juan engineered heat exchanger. When its on the muffs, the temp shots to 190 and back down 175 and holds at 180 at idle. New thermostat, and raw water impeller where istalled.I ran it the 1st time with the rad cap off until the air burped out. I'm down to a testride to see if the muffs aren't enough or the temp gauge is defective. after she heats up, the temp gauge still flucuates b/w 175 and 185 with the 160 degree termostat installed.

Any suggestions to sortout the problem?

 

[a70eliminator]

Re: 1989 omc 4.3l temp is not steady

A new engine is tight and is going generate more heat until She loosens up a little after breakin, location of your sensing bulb will effect the temp, is it at the waterneck nearest the T-stat? It's running on the warm side but still not overheating, I wouldn't worry unless I saw temps over 200.

 

[phillyc1]

Re: 1989 omc 4.3l temp is not steady

A70eliminator,

I'll run her this weekend and see how the temp is. The temp sensor is next to the t-stat housing as you described. Hope its the new engine. There was the old raw water colded setup on this engine before I installed the FWC system. IT did run with raw water a few times to test and held a temp at 120. The reason it for the low temp was obvious after pulling the old t-stat housing, no t-stat. Also, the rust chunks from a reused intake manifold were jamed in there. I flushed the engine and took a shop vac to the outlet. I made sure there was no rust chunks stuck in the intake water passages as best I could. The mechanic that installed the engine could have put a new intake manifold on it, what an *****. I pulled the spark plugs and dipstick, and, so far, no water in either. So the old intake is still functioning. But the rusted walls on the inside of the water passages would not cause it to overheat, would it?