Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

[cameron92]

So found the issue it's been having all along. The anti siphon valve was clogged up with white deposits. Cleaned it out and now the boat runs great. Only issue I'm having is the temp climbing up to 195ish on idle. If I rev it up it drops back down.

 

[Lou C]

So found the issue it's been having all along. The anti siphon valve was clogged up with white deposits. Cleaned it out and now the boat runs great. Only issue I'm having is the temp climbing up to 195ish on idle. If I rev it up it drops back down.

Wow that's great, I had the same problem with my boat when I first bought it in 2002. Now you need to test that thermostat or just replace it, make sure to use an OMC/Volvo 160 marine 'stat. I like to test them before installing. With the 160 at idle you should run between 160-170 or so. 195 is too hot and means that hot water isn't leaving the engine fast enough. Now the same issue can be caused by clogged up water passages in the exhaust manifolds and elbows, but I doubt that in freshwater you have that problem.

 

[cameron92]

Fixed the overheating issue, split the upper and lower drive units and the copper tube grommets were dried out on one side and split on the other. Replaced those as well as the water intake housing gasket. Runs almost too cool now, at idle it will cool right down to 120 or so. Rather have that problem then the overheating.

The boat hasn't skipped a beat since all this work and it's been great. Only issue I'm chasing now is the trim cylinders leaking down. Rebuilt them with a cheap kit from JLM and that worked for a day and then stopped working. So bought a used set of trim cylinders to try for 80$

 

[Lou C]

If you’re running at 120* you prob have a bit of rust or sand in the stat causing it to not close all the way. Had that many times. Glad it’s running well! The bleeding down could be the pump too.