Carbon Cleaning/Compression

I have an 83 150hp V 6 Merc..It has not been run very much in the last few years..It Starts easy, runs smooth and is capable of 5500 WOT..I checked compression just to get an idea whats going on inside..I found 5 of the cylinders with in 5psi of each other. 1 was 15psi low,port side lowest cylinder..A bore scope showed no signs of scoring.I filled the cylinder with air.Very slight air escaping from carb..A outboard mechanic said it could be carboned up rings? I want to try some Sea Foam & a product Called Quiksilver Rejuvenate 2 cycle oil..Any Suggustions TNX

Re: Carbon Cleaning/Compression

Stuck rings could be a possibility. Seafoam will help, as probably will the Quicksilver Super Duper oil. Sounds like it's got a good dose of cleaner as well. If there's any carbon in there, that should get rid of it!

If you notice no improvement in compression after the decarbonizing treatment, you might want to pull the head and check for sealing issues or piston slop.

When you have the piston at the top of the cyl, you'll be able to get a good idea of what's going on with the rings by moving the piston side-to-side in the bore. If you have seized rings the piston isn't going to readily spring back to center.

HTH & let us know what you find........ed

Re: Carbon Cleaning/Compression

TNX Ed, I will run it again this weekend. By that point if the cleaner works, Ill Know.. then I can check it Again & will check the pistons movement in the bore.I will keep you posted Perry