Engine temps with stock promax

[Rled]

You guys who are running 225 promax motors with stock cooling , with thermostats and poppit, what are your temps idling in say ,75 degree water?

 

[aj06bolt12r]

Probably about 130-140... 150 if I am giving a little gas, sort of high idle or towing another boat in.

 

[Rled]

I have a 225 promax that was originally a 260. The previous owner blew up the 260 and dropped the 225 on the 1 piece exhaust adapter plate. It was still setup like the 260 with no thermostats and with washers instead. It runs 140-150 cruising, but as soon as you drop back to idle, it drops to100 or less, depending on lake temp. I'm going to switch to the 2 piece plate to maintain temperature better. It loads up some at idle probably because the acu is seeing cold engine temps. I was just wondering if with the factory cooling setup, for the steel sleeve 225 ,if it maintains temperature with different lake water temps before I change the exhaust plate. Thanks for the reply.

 

[aj06bolt12r]

Yeah it should maintain temp or pretty close anyway.. I think your on the right track... Other people could probably give you a more detailed answer on what exactly you should do.

 

[Rled]

I've read probably one hundred pages on scream and fly and other sites relating to mercury cooling. It all seems to boil down to , Mercury already figured it out. I've worked on car engines all my life but never pulled the power head off of an outboard . I may try to find a Mercury mechanic to do that job .

 

[aj06bolt12r]

If you have mechanical aptitude and patience... both required to work on car engines... I think you can pull a power head. I'm in the same boat "pun intended" I've been an auto diesel mechanic all my life... Not as well versed in outboards but I will work on my own stuff or help my friends mess with their stuff... I have never tried but I have read that it can be hard to find a commercial mechanic that is willing to work on the "race motors"

However if you know of a competent local marine mechanic and would rather spend the money than deal with the headache... I totally get it.

 

[gmorgan]

The more free flowing cooling system of the 260 is best suited for engines that see in excess of 7,000 rpms. It yours never reaches that level of rpm, I’d switch to a two-piece plate. If you run it over 7,000, I’d stay where you are.

 

[Contractor]

I didn't really see any problem with one piece plate. Temp would cool down as you slowed. I guess

 

[fuminsonotx]

I didn't really see any problem with one piece plate