Mercruiser 37 190hp High temperature

" On my mercruiser 3.7 190hp f

" On my mercruiser 3.7 190hp fresh water cooled at idle my temperature goes up to 180-185 and running at 3500rpm goes up to 200+ range in a very short distance. I'm using a 160 thermostat which, through testing, begins opening at 160. I replaced the waterpump and water hose in the outdrive and have good water flow. The temp of the coolant in the riser is 143 at idle so the heat exchanger is cooling the coolant by 40 degrees at idle. The exhaust and riser doesn't appear to have an excessive amount of corrosion. I guess my question is are these temp too high and if so what could be the problem? How would you test the temp sensor and or test for the correct temp at the thermostat. "

"Check which thermostat is spe

"Check which thermostat is specified for that engine, I would be willing to bet it should be a 140

Rick"

i think fresh water cooled is

i think fresh water cooled is 160. you must have a digital thermometer to test riser temp so whats the temp at the thermostat? if its higher like 180 than id bet your thermostat housing is plugged

"This was orginally posted May

"This was orginally posted May 04, even though my thermostat appeared to be working properly I replaced the thermostat and that solved the problem. This year it was the voltage regulator system which I purchased the changeover kit for $99 and a 1-wire alternator $60 off of ebay. A much better and cheaper set up for this engine for those of you thinking of doing the swap."