87 Force 125 / No compression on 4th Cylinder

PelagicOne

Recruit
Joined
May 13, 2004
Messages
1
87 Force 125 / No Compression on 4th Cylinder:<br /><br />- Newly acquired from wife's uncle<br />- Only 220 hours<br />- Just had lower unit replaced with rebuilt lower unit<br /><br />So I take the boat out for a day of high speed fun on the San Francisco Bay, on mirror-like conditions (5/1/04) and went through about 15 gallons of gas/oil mix. As we're returning to the ramp after a long day, the engine suddenly stops running from a full throttle run. I confirm there's still a half tank of fuel, restart the engine and run for another two minutes, continuing home. Engine stops once again. I wait five minutes and restart the engine. This cycle continues a few more times before I decide to limp home at around 5 knots. The engine gets all the way back to the ramp (an hour later) but sounds like one or more cylinders is either misfiring or not firing at all. It seems to be idling quite high for only 5 kts, and a high-pitched metallic knocking is heard.<br /><br />The next weekend my buddies and I start up the engine in the yard (running the water flush, of course) and discover the plugs are firing, but the fourth cylinder has no compression.<br /><br />I'm guessing either bad piston rings, broken piston, or I'm totally screwed.<br /><br />What do I check next? Any advice is most welcome.
 

Oldsaltydog

Petty Officer 1st Class
Joined
Jan 27, 2004
Messages
322
Re: 87 Force 125 / No compression on 4th Cylinder

You are correct. It does not sound like good news. Do you know a good mechanic who charges reasonable rates? ( I could recommend one for the Sarasota, FL, area, but that would not help you by the Golden Gates at all. Sorry.)
 

WILL23

Cadet
Joined
Jul 14, 2003
Messages
21
Re: 87 Force 125 / No compression on 4th Cylinder

I have the same model and the same problem. You should pull the head to get an idea of how bad the damage is. Check for scoring - rub your finger nail against the cylinder wall, if it feels rough you are in need of a rebuild. If you are very lucky you could have just blown the head gasket. With zero compression that is unlikely. <br /><br /><br />Good luck
 
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