Low Compression

[Burke]

I have a '77 85HP Evinrude. I did a compression test and I have one cylinder that is very low. Three of them are around 140psi and one is 45psi. Are the rings the only suspect or are there other things that can cause low compression? I just bought the boat and the motor does run. Any help or thoughts would be very appreciated.<br /><br /><br /><br />------------------<br />- Burke<br /><br />If I'm not working on the boat, I'm working on the Mustang.

 

[Dhadley]

Re: Low Compression

Pull the heads and tell us what you find. Most likely the low cylinder is on the starboard side, right?<br /><br />Good luck!

 

[hleitao]

Re: Low Compression

Just curious...why would you suspect the starboard side?

 

[manowar]

Re: Low Compression

dont start that motor till you get that head off could be carbon build up and or rings scorched cylinder and or piston and or the head and thats all it could be if you replace the rings make sure you put the rod cap back on the same way it came off they have one way matching ends and the rings also have a top and bottom other cylinders sound great going thru the same thing here good luck