Yamaha 115 v4 compression

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Guy
long story short, managed to in seize the yam yesterday but the old thumb test and turning by hand suggests that one cylinder is almost non existent on compression. Could this all be down to a sticking ring ? I’m thinking it’s unlikely. The head is coming off that bank today for a look.
 

Doh

Petty Officer 2nd Class
Joined
Aug 12, 2008
Messages
187
Lack of Oil? How fast/long did it run before seizing?

Most likely a scuffed piston. Soft seize is piston and rings and a honing maybe some Muriatic Acid before the hone to remove the Aluminum. Hard seize/High RPM, look at rod and crank bearings, crank seals, 1 or more pistons, and all 4 ring sets.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Thanks for the reply. The story I got was that the oil fees tank in the bilge filled with water after leaving the boat explosed to the weather. They didn’t know it had and ran the engine. Eventually it ran rough and they kept trying it. It eventually seized.

Simce my post I’ve taken the head of the left bank. It wasn’t good. Clearly water been in there and one piston completely damaged. It’s hit the head too. Worried for the crank now
 
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