By the way guys just wanted to let you all know, bought the boat next day went out for sea trial. start it up first crank it jumped to life, then ran almost a mile at WOT Then died like I turned off the key. feeling guilty that maybe I should have drained gas, and started new. by the way almost 3 a.m. Here in Florida had a few to drink !!!

Compression should be roughly 140-150 for a 140 looper. Small bore and big bore V4's both ran pretty high compression. Most likely you put the screws to it with bad fuel and leaned it out. Loopers HATE being run lean, and will smear the pistons in a HURRY. It only takes an overheat for about 15 seconds to smear a piston in one. They are AWESOME engines when setup and running right, but one little problem and they will self destruct in a matter of seconds. The T-stats and bypass valve can also cause this to happen. You want the engien to idle at about 150-170 degrees, but at WOT you want it to drop back to about 125 to keep from sticking a piston.

Ferm and Skools Out are the looper experts around here.But sounds like your motor is dead. If you want to eliminate another variable, try your compression tester in another engine to make sure its reading correctly or try another compression tester on your engine. Next step, pull the heads and take a look.

opened it up walls of the cylinder are very scored. here is a picture. looks like motor was never properly flushed out heavy corrosion.

actually corrosion doesn't look that bad for a 20 something year old engine ran in salt water.
just one scored cyl or were they all harmed? are you sure the gas had oil in it?

the Pistons walls were just scored not hammered not sure if the previous owner had oil in it I know the VRO was disconnected and he said he was using Mix

thats melted aluminum from the piston stuck to the walls of the cylinder

spare, is that lack of oil or overheat?
shurlock, i said harmed, not hammered, was wondering if all cyl looked the same

Look at the pistom dome, that engine LEANED OUT BAD! theres not even a trace of black carbon or soot on it. A looper should always have some sort of soot on the piston dome when they are jetted to live, and there should be some traces of wetness.

Looking at your pics it looks like a small bore engine which were ALWAYS prone to overheating due to there design. Where are you located at?

what he said