Little Advice/Re-Assurance Needed

[rhickox]

I have some friends running small steel sleeve motors...Yamaha 40's, OMC SST 60's, etc..... They all run restricter washers in place of the tstats.. During the hot months they always seem to hold up.. When it starts cooling off and the water temp drops, they start sticking pistons!! Then they start thinking they need to fatten up on the jets!! My opinion is they need to put the tstats back in or restrict the water flow some more.. I think they are cold siezing.. Any opinions from anyone else?????:confused:

[rev.ronnie]

Are they 4 corner or both skirt scuffing? That would be cold seize. Intake side scuffing is lack of lube, exhaust side is usually lean condition or timing.

The piston will tell the story.

[930turbo]

" There is a lot of discussion around thermostats and restrictor plates on the forum. My motor currently has restrictors in it but I'm pulling them in favor of the factory's original plan. I built many motors back in the day and alway used thermostats whether they were for fishing or high performance. I never viewed them as the enemy. This is a lake motor that will be driven at less than WOT for much of it's life so I decided to let them do their job of regulating temperature at practical speeds. I think fresh thermostats are the key to success."

[Jay Smith]

I agree,
Those engineers didn't fall off a turnip truck. The steel sleeve must expand quickly to try and catch the quickly expanding piston size. If the cooling media is not stopped until a target temp is reached and full expantion is reached by the sleeve a good chance of seezeure can occur. I also have learned a money saving lesson with the use of 100% syn on steel motors and that is DON'T use it. In my earlier years I had several failures until I saw the light and now run NOTHING but a blend on steel..

Good luck,
Jay

[Hank W]

I agree,
Those engineers didn't fall off a turnip truck. The steel sleeve must expand quickly to try and catch the quickly expanding piston size. If the cooling media is not stopped until a target temp is reached and full expantion is reached by the sleeve a good chance of seezeure can occur. I also have learned a money saving lesson with the use of 100% syn on steel motors and that is DON'T use it. In my earlier years I had several failures until I saw the light and now run NOTHING but a blend on steel..

Good luck,
Jay

Do you recommend blended oil for Pro Max motors?

[TEXAS20225]

sounds like it to me on steel sleeve motors and i agree

[Hank W]

Well that is good to find out since I just got a modified Pro Max and have only run it once. I'll make the switch then. What brand(s) do y'all recommend?