I have a 1986 Evinrude 110 HP outboard. If I have no compression in once cylinder, could it be a reed valve?

Question

The motor has been missing for a while, and I've noticed a loss of power (somewhat gradual). Constantly quits now. When the problem first happened, we were up and running, and it just died. I've been able to get it running since, but it wasn't ever the same. Now 3 cylinders are at 90 psi, one is 0. I'm trying to figure if it is likely a ring, or reed valve (or something else??).

Answer 1

Either a piston Or head gasket since that old if use in salt water your in for a fun time pull the head and look that will tell you what let go>Does the plug have aluminum on it ???

Answer 2

Boat motors use ports and not reeds to divert exhaust gases(2cycles). Here's three possibilities. To hot spark plugs in that low cylinder and theres a hole in the piston. There are no rings left on that piston that is low on compression. I thought about a head gasket but that would show at least two low compression readings on paired cylinders. The last posibility is a small hole between the water jacket and the affected cylinders. This is common on motors run in salt water or with alot of miles wear corrosion wear on inner separator plates.

Answer 3

It could be a stuck ring. Have you tried running carbon cleaner through it? Sometimes it will help. Many like to use Seafoam. Most parts store have it. It be cheap to try.

http://www.seafoamsales.com/

Answer 4

Gasket, or you ate a piston ring, means the head got a bit munched too, it can be fixed but, you'll need shop support, it may exceed the value of the engine though.

Answer 5

could be

1) a bad valve

2) broken rings

3) blown head gasket