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1985 Merc 50hp 4cyl died at WOT very smokey/hot

R

rockinhitz34

Member
Hi all,

Appreciate your thoughts on this. Was running at wide open throttle today (13' Boston whaler) and I noticed I started to lose power, turned around saw the engine smoky so I cut it. Wouldn't start again, got a tow home.

I did a quick compression test when I got home and had:
1. 125
2. 100
3. 75
4. 100

Pretty miserable, my last cold compression test was ~120 on all cylinders. When I pulled the plugs at home they were all still really hot, probably ~45 minutes since the engine had run. It didn't sound like there was a problem with a piston through a cylinder wall or anything.

I'm planning on pulling the lower unit tomorrow to check on the impeller/water pump, but any other suggestions? Is this thing lost on bad compression, or do I have a chance to bring it back? Appreciate your thoughts and next steps for diagnosing what's wrong.

Thanks!
 
Many of these motors do not have a warning horn or an overheat shutdown feature.-----They need a new impeller every 5 years.------Too late now.------It needs a rebuild !!-----Most folks learn about outboards the expensive way.----Sorry.
 
Thanks for the thoughts I appreciate it. I’ve done the water pump service every season (or every other in a few low use seasons).

When I pulled the lower unit this morning I noticed tons of emulsified fuel/water on the exhaust and the water tube seal had gone, I found a piece of it in the exhaust. The impeller looked ok, but was warped from the heat transfer down the driveshaft I’m guessing. So bummed to lose the power head on a stupid water tube seal.

any good resources available on rebuilding one of these, outside of the seloc manual? I don’t really have the tools to do it, but thought it might be a decent winter project. Is it even worth it?

appreciate the thoughts.
 
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