Thermostat replacement
 

Okay, here's an easy one. I'm thinking of replacing the thermostat on my 454 Mag MPI since it is original (over 4 yrs old). Any suggestions on what part I should use? Stock MerCruiser? Somebody else's product?

Dustin Whipple already suggested that I drill 4 to 6 3/16" holes in the stat to allow the engine to run a little cooler.

Thanks,

I would only use Merc parts and don't drill any holes!! The ECM needs the right one with no holes.

Stock 454 Mag MPI. Dustin recommended drilling the holes to allow the engine to run slightly cooler and generate a little more power. It was not in response to my engine overheating or anything like that.

If it ain't broke, don't fix it.

Drilling a few holes in a t-stat isn't going to give you any more power.

If I had heard the tip from anyone except Dustin (or Dennis), I would be skeptical. Hard to question those guys.

I would suggest that you use only the thermastat that MerCruiser calls for. Since you have a fuel injected engine the computer adjust the fuel mixture based on the temp. If you run the engine below spec. you engine will run rich.

Dail