Mercruiser 120

[M Lamb]

Howdy. I need some help with my Mercruiser 120. A few weeks back I found that my fuel tank has developed a leak. Not wanting to wait to fix it, I plumbed a portable to the engine. Worked fine for a brief time, then while running it hard the oil pressure started to fluctuate and it began running hot. Since then I can run it below 10 mph for a half hour or so, then it begins to stall out and is impossible to start. At idle it also begins to stall. Any thoughts? Thanks, Mike

 

[WillyBWright]

Re: Mercruiser 120

Either it overheated, or your oil diluted with gas. If you're using a portable tank and close the vent, gas might be forced past the float valve if pressure builds. I'm betting on the water pump. When oil gets hot, it gets thin and pressre drops. Check the gearlube in the drive, too.