225 promax with one piece adapter plate

[Go Time]

Does the Factory 225 Promax Offshore that uses the one piece adapter still use the poppet valve and thermostats? Don't see two different cooling system set ups in the parts breakdowns.

[Eagle One]

Some engines do and some don't. It depends on the purpose the engine was made for. The promax series leans more to the recreational side while the 260's and such are more performance oriented.

[Go Time]

I assume the 225 Promax with one piece adapter only came in one cooling configuration from Mercury as a production engine. I know the 260/280... high RPM race engines do not use the poppet and thermos....but I'm not sure the 225 didn't when used with the one piece adapter. Hoping some with one will respond. Thanks Mark

[hullbilly24]

I had a 2000 model factory 15 inch Pmax and it had tstats.

[Go Time]

Hullbilly....Did it use the poppet valve also?

[Erine]

I purchased a 1999 225 pro max powerhead that was on 15 in offshore mid had stats and poppets and was on a two piece plate.

[hullbilly24]

Hullbilly....Did it use the poppet valve also?

Yessir............failed to mention that mine had a one piece plate also.

[Go Time]

Hullbully...Thanks, that's what I needed to know. I wonder if I will loose any performance using a 280 oval tuner vice the 225 oval tuner...any thoughts?

[hullbilly24]

Well...some may disagree, but unless you're concerned with the very fine details of a racing application, I highly doubt you'll see a difference.

[RB in NM]

my stock 99 225 PM also came with a 1 pc plate, with poppets and stats. WOrked ok for cooling till I started modding and turning a lot higher than stock rpm's. I then went to Marles cooling and restrictor washers.

[Go Time]

That was what I thought the situation was, but I wanted to confirm it with the experienced guys here on S&F. I don't plan to mod the engine or turn it over 7K, so I think I'll leave the cooling stock even though the poppet doesn't do anything. Thanks guys....I appreciate your responses. By the way, I have a 2003XB too.


Mark

[Go Time]

Does any one know what size are the water drain holes are in the factory 225 Promax one piece adapter? Thanks Mark

[Greg G]

Does the Factory 225 Promax Offshore that uses the one piece adapter still use the poppet valve and thermostats? Don't see two different cooling system set ups in the parts breakdowns.

That was what I thought the situation was, but I wanted to confirm it with the experienced guys here on S&F. I don't plan to mod the engine or turn it over 7K, so I think I'll leave the cooling stock even though the poppet doesn't do anything. Mark

Couple seasons later and not sure if you kept the Promax Offshore, but how did you make out with cooling using tstats?

[ironhead785]

so did it work ok

[Go Time]

Actually, I did the Marles setup and it worked OK, but definitely ran cool in Spring & Fall. I then built a powerhead and went to break it in with the one pc adapter and it cold seized. I didn't need to run the 1 pc, so I put the 2 pc adapter back on. I think the 1 pc will work, but the holes in the adapter must be smaller than suggested by marles and poppet cover fitted with a discharge hose where the flow can be adjusted to dial in the temperature for the operating conditions.