Re: "Newer" 25/35hp OMC compatibilities

[johnyrude200]

So revisiting this thread, I’m going to have to pull the exhaust cover and examine the inner exhaust baffle, pull the powerhead to make sure there isn’t a crushed upper water tube grommet, and double check the impeller housing for air leaks.

I ran this motor on my pontoon and there is certainly an exhaust leak somewhere causing back pressure into the cooling system. The motor is going back and forth between pumping just moderate water. The water is getting as far as the tell tale, but then not making it’s way through the rest of the motor, and sometimes it’s even stopping and not making it through to the tell tale.

I do remember this motor having mud dubbers in the outer thermostat cover passages, and even in the exit hole. I’m wondering if they may have climbed up through the upper water tube grommet in the exhaust housing and nested on the inner exhaust bypass passages (port side of motor) as well. This motor had been sitting with the gearcase off for several years in an unheated mechanic’s barn.

I ran it for a few hours yesterday with no thermostat out on the boat and caught it stop pumping water a few times at low idle/neutral. Turned if off for a few seconds, started back up, and WHOOSH, out comes plenty of water and steam as it’s cooling back down and running cold, if anything. I have observed repeated plugs in the telltale as well, using weed wacker wire to unclog.

Will report back once I figure out the culprit!