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Near Catastrophic Failure-0x66 250-Interesting Findings-Must Read for 0x66 Owners
Wondering if anyone has had or heard of these similar circumstances that lead to near catastrophic failure. The engine is a 2001 0x66 v250 SS 76 degree SX250TURZ.
After hearing some distinct and loud rattling sounds, upon opening her up, she fell flat and I heard the distinctive clunk and the dreadful sound of metal passing through the exhaust. Quick compression test on the water, 30 psi cylinder #4. Made it back to the dock, took apart the power head and found:
#4 piston crown outside perimeter completely destroyed from debris along with corresponding damage on head. 1/4 inch crack in sleeve vertical wall connecting to 1/8 inch crack on horizontal surface. Caged needle bearing completely exploded, only some small needle bearings left. Right side pin washer missing. Chunk of piston skirt missing.
The issue:
So it turns out that the caged bearing that encompasses the wrist pin and sits inside the small end of the connecting rod, had worn the pin out by as much as 1/8 inch in some spots, to the point that the were a definite shoulder, and either the wrist pin just finally exploded or it hit the side of that shoulder and exploded, taking out the washer, causing the connecting rod to slap the piston and break a piece off.
Interesting:
After examining all piston sets, turns out each one had some wear in the wrist pin from the bearings, more wrist pin wear than bearing wear. #3 getting close to ending up like #4. Also, # 1 and #3 and #5 cylinder jugs had rotated sleeves. Not horrific but at least ½ inch out of position. Machinist says he’s been in business for a LONG time and never seen it, says from an extreme overheat, I say it came that way. Who knows. He needs to work some small miracles on her. Thermoswitches and t stats check out ok. Thermosensor seems to be having some issues. O2 sensor has been getting fouled up pretty quickly past couple of months, seems that sleeve rotated, misaligning the hole in the #1 cylinder wall and the small pickup/exhaust tube in the O2 sensor port. Everything else functioning as should be.
Result:
Machinist is working on putting in a new sleeve and getting the other sleeves back into position. A hell of a better deal for the time being than a new or reman powerhead. Replacing all worn and damaged parts. Able to lift the powerhead off the boat while in the water, maybe 100 lbs. Getting back on will be tricky along with reassembling the crankcase. Fuel injectors came back from service with clean bill of health, 2 were a little off but still in spec. $20 each, 24 hour turn around time-Southbay Fuel Injectors on Long Island.
Wondering if anyone has heard or seen anything similar, looks like normal wear and tear but with less than 600 hours on her, seems odd. Normal gas from the gas dock, higher quality oils used, routine general maintenance all season. Have used about 35 gallons of regular 87 from the on land gas station. Lower octane than I should have been using at times, but doubt this had much affect. Had some issues with water in the gas, definitely had a good amount sitting on the bottom of he tank but you could always tell and remedy the problem before it got out of hand. Normal Lp fuel pump and VST screen issues through out the years. Blown head gasket from an overheat late last year, faulty thermostat. I suggest checking the 2 thermoswitches and 1 thermosensor every so often. Surely is easy enough.
After hearing some distinct and loud rattling sounds, upon opening her up, she fell flat and I heard the distinctive clunk and the dreadful sound of metal passing through the exhaust. Quick compression test on the water, 30 psi cylinder #4. Made it back to the dock, took apart the power head and found:
#4 piston crown outside perimeter completely destroyed from debris along with corresponding damage on head. 1/4 inch crack in sleeve vertical wall connecting to 1/8 inch crack on horizontal surface. Caged needle bearing completely exploded, only some small needle bearings left. Right side pin washer missing. Chunk of piston skirt missing.
The issue:
So it turns out that the caged bearing that encompasses the wrist pin and sits inside the small end of the connecting rod, had worn the pin out by as much as 1/8 inch in some spots, to the point that the were a definite shoulder, and either the wrist pin just finally exploded or it hit the side of that shoulder and exploded, taking out the washer, causing the connecting rod to slap the piston and break a piece off.
Interesting:
After examining all piston sets, turns out each one had some wear in the wrist pin from the bearings, more wrist pin wear than bearing wear. #3 getting close to ending up like #4. Also, # 1 and #3 and #5 cylinder jugs had rotated sleeves. Not horrific but at least ½ inch out of position. Machinist says he’s been in business for a LONG time and never seen it, says from an extreme overheat, I say it came that way. Who knows. He needs to work some small miracles on her. Thermoswitches and t stats check out ok. Thermosensor seems to be having some issues. O2 sensor has been getting fouled up pretty quickly past couple of months, seems that sleeve rotated, misaligning the hole in the #1 cylinder wall and the small pickup/exhaust tube in the O2 sensor port. Everything else functioning as should be.
Result:
Machinist is working on putting in a new sleeve and getting the other sleeves back into position. A hell of a better deal for the time being than a new or reman powerhead. Replacing all worn and damaged parts. Able to lift the powerhead off the boat while in the water, maybe 100 lbs. Getting back on will be tricky along with reassembling the crankcase. Fuel injectors came back from service with clean bill of health, 2 were a little off but still in spec. $20 each, 24 hour turn around time-Southbay Fuel Injectors on Long Island.
Wondering if anyone has heard or seen anything similar, looks like normal wear and tear but with less than 600 hours on her, seems odd. Normal gas from the gas dock, higher quality oils used, routine general maintenance all season. Have used about 35 gallons of regular 87 from the on land gas station. Lower octane than I should have been using at times, but doubt this had much affect. Had some issues with water in the gas, definitely had a good amount sitting on the bottom of he tank but you could always tell and remedy the problem before it got out of hand. Normal Lp fuel pump and VST screen issues through out the years. Blown head gasket from an overheat late last year, faulty thermostat. I suggest checking the 2 thermoswitches and 1 thermosensor every so often. Surely is easy enough.
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