4.3 MC temp

[sumcat1]

I have a 2005 4.3 190hp MC with 20+ hrs.The temperature gage has always read just over 180 when warmed up on muffs or on the water and I never notice any fluctuation.This is a new boat with MC gages.The service manual calls for a 160 degree thermostat.Does something need to be checked before the warranty runs out or has Merc changed the specs? I hesitate to open anything while under warranty.

 

[QC]

Re: 4.3 MC temp

Does this boat have "closed" cooling? A closed system would have a radiator cap and antifreeze inside the engine. This type of system runs hotter (good thing if "closed") than the more typical "open" or "raw water" cooling system that use lake or seawater to cool the engine directly. "Closed" or "freshwater" systems use the "raw" water to cool the coolant circulating in the engine and the two do not mix.

 

[Don S]

Re: 4.3 MC temp

It shouldn't be running over 180° on the muffs. You might get one of thse digital temp guns and take a reading right at the temp sending unit. Those engines will run about 170° on the muffs, that temp opening of 160° is where the stat starts to open.<br />Is your engine raw water or FW cooled (heatexchanger).

 

[sumcat1]

Re: 4.3 MC temp

It is raw water cooled. There is a numbered mark on the gage at 160 and 200 and an un-numbered mark half way between which I assumed to be 180.It runs about the width of the needle on the high side of this mark.I'll raise the issue with the dealer.The lower unit was swapped with another boat before I took delivery because the skeg was bent.Never know.I'm at about 24hrs now and have had no problems.