Burned electrode and no compression

[wreckless]

Engine: 1997 5.7 Mercruiser
Problem: Number 2 plug has electrode burned off and no compression on that cylinder. Engine overheated.


Question: I am helping a friend with his boat and we found the above problem. What would cause loss of compression and burned plug electrode? Would a stuck valve cause the problem or broken/stuck rings?

I know we are going to have to pull heads to check but looking for a little insight on what could cause problem.

Thanks....Paul

 

[Apollo75]

Re: Burned electrode and no compression

Fuel detonation / explosion ---- much hotter than the normal burn and can burn holes in the tops of pistons etc.

Get out the tools and check the damage

There is a long list of things that can cause this:

High rpm
low octane fuel
anything in the combustion chamber that can glow and light the fuel mixture too early
timing off
too much advance
engine not cooling --- especially around the head area
etc.


See this post : http://forums.iboats.com/showthread.php?t=351295

Good Luck

OFM