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Mercury 1987 60 hp overheating

S

slk

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Guys I have a 1987 Mercury 60 hp that gets hot at full speed. If you just cruise at like 3200 rpm everything runs cool. I have replaced the impeller, and have a good stream water coming out. I am thinking of taking the rear cylinder cover off and checking the water passages for obstructions. Has anyone ever had this type of problem? Any suggestions are very welcome.

Steve
 
Yup. Overheating (and frying the top cylinder) is a major problem with those engines. I run them exclusively on my little boat--got several of them--and have learned a trick or two:

1. The impeller is too small for that engine, which needs all the cool water going through the power head it can get. Instead, some boob at Mercury decided to send some of it through the fuel pump (for an improved idle? Didn't help. Trust me.) You need to remove and block off this line so ALL the water goes through the power head. Remove the fitting (under the PH on the right side in the exhaust adapter plate) and screw in an 1/8 inch pipe plug.

2. The TOP carb should be running a .0785 jet (or thereabouts) where as the lower carb should have a .072. If not, change them! The jet is conveniently located inside that 1/2 inch (wrenching) plug at the bottom, of the carb.

Jeff
 
And it was NOT necessary! I've run triples for years without that nonsense and never had a problem. By contrast, of the 12 plus triples to pass through my shop, only one didn't have a burnt top piston.

Here's a photo of the latest one. I was able to save the block, but the rod was scrap.

Jeff
 

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Can you show me a picture of what needs to be done. I see the block that the fuel line goes through.
Thanks Much

Steve
 
I see the line coming from the side of the block to the square box where the fuel is going through. It goes in the side of the box, but do not see where it comes out???? Does it just circulate back and forth through that one tube. So do you plug where it comes out the engine, and plug the square box also where it goes in it.Just by passing the box????
 
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