75 hp Evinrude Compression

[rudy]

" Joe, Thanks for your help, s

" Joe, Thanks for your help, sorry to be a pest.
My Evinrude manual doesn't give a compression spec range. I need to know the compression specs for my 7.5 hp 83 Evinrude. I'll have my grandchildren with me at times and I want to have confidence that it's safe and reliable. Have thought maybe of R&R: Fuel pump, Carb and water pump. Is there any of these thing you would recommend and are the repair items available ? Also how would I know if it's been overheated ?
Thanks again, Rudy "

 

[joereeves]

"Rudy.... I've yet to come

"Rudy.... I've yet to come across any specs related to the required compression either, and have just browsed thru a few manuals on various horsepowers to see if I may have simply ignored that area.... nope, it's simply not there.

Working on the engines day in, day out, one gets accustomed to what the compression should be, and for that matter, what it feels or sounds like when the engine is either cranked over with a starter, or pulled through with a manual starter.

On a 1983 7.5hp, being pulled through rather quickly, and using a screw in type compression gauge, I'd say that a even reading on both cylinders of 80 psi and up would be fine.

Replacing the fuel pump, or simply having one on hand would be a good idea. If the water pump hasn't been changed in a couple years or more, it would be proper to replace the complete water pump assy, not just the impeller. The carburetor can be rebuilt to new condition via a carburetor repair kit.

The fuel pump, water pump, and carb kit are available at any dealership, and possibly at NAPA and other outlets (Sierra, Aqua Power, etc)

If the engine has been overheated bad, that would result in a change of color at the cylinder head area (brownish), plus some wires (insulation) would melt, head bolts would be loose, that sort of thing.

Joe (30+ Years With OMC)"