is 140 degrees to cool?

[scutly]

hey guys, i have a new to me 95 regal merc 5.7 alpha gen2. fresh water cooled conversion. she almost overheated on 4th day out. got to 220 degrees after running at 180 on the first three trips since i bought her. so i changed the impeller pump and went to change t stat and there was none. i installed a 160 tstat and now she wont get over 140 degrees. im assuming my tstat is not opening then? should i run a 140? or none? the day i bought the boat the old owner fried the impeller on the driveway i think starting it for me and running for 5 minutes but he forgot to turn on his hose. got to 180 degrees before he noticed his hose was off. i didn't know any better till i read you fry impeller after running dry for 30 seconds. also, i installed the tstat in the normal spot on intake manifold. but im wondering if its supposed to go in the small tube coming off heat exchanger that looks like it will fit the tstat. im also wondering if that is an accurate reading on engine temperature because sending unit is on heat exchangerany help would be appreciated.
thanx
paul

Make : mercruiser
Model : 5.7
Year: 1995

 

[PitchFork]

Re: is 140 degrees to cool?

I have a 1994 5.0L that the manual calls for 143? T-Stat and it runs around 150? to 180?. If you have a 160? T-stat then I would think you should be running around 170ish. 140 with a 160? T-stat seems a little low. Sounds like the 160? T-stat you have is not closing.