[jackman1939]

I bought this engine new in 1998. It has always run very good. I use 7712 plugs and after reading the indexing information, I always index the plugs. The #3 plug always seems to be grossly fouled after only 2 trips (30 miles each). I clean it and reinstall it. The engine usually tacks out at about 4300 rpm. I have a 1996 OMC Neptune center console boat. The prop is a 14 1/4 X 21. The boat usually has a max speed of 44 mph. The last 2 times I went out, I noticed the top speed was only 39 mph. Ran fine though. Went out Saturday and decided to come in early because of a big storm approaching. Was tooling along at top speed for about 10 minutes, when all of a sudden, the engine made a loud noise and started running very sputterly. Saw a little smoke coming out from the cover. Turned the engine off, took the cover off - it looked ok. Started right up, but sounded terrible. Shut it down and called Sea Tow. When I got home, I took the cover off and removed all the plugs (they all looked ok). Put my finger over the spark plug hole and had my wife crank the engine – all cylinders had compression and suction. Upon further inspection, I noticed a few pea sized pieces of metal laying inside. Spotted a hole in the crankcase, between cylinders 2 and 4.Hooked up my laptop, connected the test wire from the engine to the serial port and ran the OMC diagnostic software. It came up with 1 error code: "Intermittent 35 - oil pressure switch malfunction. Oil pressure switch is not opening or the switch harness lead is grounded".I got not indication on the OMC instrument cluster of any oil problem. Checked the oil reservoir and it was 3/4 full. Pulled the rubber line off the metal line where the oil comes into the engine. Hooked up a piece of clear tubing to the metal line and sucked on it - oil was present there.SOOOoooo, I am getting ready to tear the engine apart and try to fix it.About 4 years ago, the oil light and beep came on every now and then. I replaced the oil pump and that fixed the problem.Any tips you can give me would be appreciated. I am not an outboard engine mechanic, I just am pretty good at fixing stuff.thanks,Jack

[jackman1939]

My engine is a 150hp.

[seahorse5]

Chances are the damaged rod and broken crankcase were due to overpropping the motor and causing it to "lug" itself to death.That motor should have been propped for 5300-5500 rpm which would have been at least a 17" pitch prop, not a 21" turning only 4300 rpm.It is not economically feasable to rebuild your motor as the '97 and '98 versions have next to no trade in value when they are in good running shape.