1989 175HP Evinrude Low Compression

[kmbvhlowe]

I have a 1989 175 HP evinrude VRO Engine. Did compression check yesterday and one cylinder is reading 30 psi. All others are between 95 and 105. Do I need rings?? or should I pull the head or could a decarb help???

 

[jonesg]

Re: 1989 175HP Evinrude Low Compression

Seems low for seafoam, its good but can't perform miracles.
Pull the head.

 

[Cricket Too]

Re: 1989 175HP Evinrude Low Compression

I'd try a decarb before anything else, could be the rings in that piston are stuck. Any metal on the plug when you took it out to do the compression check? Did you look down the cylinder to see if you could maybe see any damage?

Do a good decarb or two, and see if you can get that cylinder up, if not I'd take the head off and look for damage.

 

[kmbvhlowe]

Re: 1989 175HP Evinrude Low Compression

I didn't mention that the boat had sat for two years prior to me purchasing it. Could sitting like that cause the ring to stick?? Will try decarb first day off work. Thanks for such quick response.

Will pull head if decarb doesn't work. Long shot but worth a try.

 

[itsaboattime]

Re: 1989 175HP Evinrude Low Compression

I would shine a flashlight down the plug hole and look at the piston. Check for carbon. Check for damage. Try to look at the cylinder wall, look for scratches or gouges.
Take a good hard look at that plug. Is there anything on that plug that shouldn't be there??

 

[kmbvhlowe]

Re: 1989 175HP Evinrude Low Compression

Actually that spark pluig was the cleanest of all 6. I will look inside of cylinder tomorrow or Sunday. Thanks.

 

[emdsapmgr]

Re: 1989 175HP Evinrude Low Compression

A great engine. Unlikely a decarb will bring back a cylinder with only 30 lbs compression. Possible a leaky head gasket. Follow jonesg suggestion and pull the head. Inspect the top ring with a flashlight to see if it is intact. Check for dents on the piston top and head surface.