1969 Mercury 80hp Low compression

[frabcabert]

Hi, My 1969 Merc (80Hp) has a compression of about 45 at the top piston and 125-135 on the bottom three. Is there anything I can try before I attempt to replace the rings/piston? I just purchased the motor and have not yet started it. The previous owner says that it ran fine, but he did have some difficulty starting it.

 

[Barnacle_Bill]

Re: 1969 Mercury 80hp Low compression

You might luck out by doing a de-carb. Check the FAQs for instructions.

 

[frabcabert]

Re: 1969 Mercury 80hp Low compression

Thanks Bhile, I'll give that a try.

 

[arsenalpsu]

Re: 1969 Mercury 80hp Low compression

If that doesn't work to free your rings than you have no other option. I would bet that the damage is already done.....you may get higher compression after you spray the oil (helps bad rings seal better) in there but once you start her up and the oil burns off it'll go back down.