Weird pattern on rod bearing
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Weird pattern on rod bearing
I have my suspicions as to what is happening to this bearing but I wanted to see what the brain trust here has to say as well?
A little history on this engine, remanufatured (Not by me) 1998 4.3 Chevrolet/Mercruiser marine engine, less than 20 hours on the engine.
Customer states it over heated, #5 dropped a hard seat and cracked the head, this is the upper rod bearing for 5.
A little history on this engine, remanufatured (Not by me) 1998 4.3 Chevrolet/Mercruiser marine engine, less than 20 hours on the engine.
Customer states it over heated, #5 dropped a hard seat and cracked the head, this is the upper rod bearing for 5.
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Re: Weird pattern on rod bearing
That looks like a long thing piece of debris got in there, and got stuck one place, and began getting turned sideways and hammered, turned then hammered, over and over.
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Re: Weird pattern on rod bearing
Could have been caused by water that got into the system via the cracked head, i.e. water jet, creating extreme pressure as the bearing went into the hydrodynamic oil wedge situation.
Bill
Perfect Circle Doctor of Motors certification
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ASE Master Certified Engine Machinist (+ two otherASE Master Certifications)
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Perfect Circle Doctor of Motors certification
SAE Member (30 years)
ASE Master Certified Engine Machinist (+ two otherASE Master Certifications)
AERA Certified Professional Engine Machinist
Re: Weird pattern on rod bearing
Interesting the damage is off-centre. Is the damage to the piston crown on the same side of the assembly? Is the crank damaged?
Will be interesting to learn whether a bearing shell can fail with a pattern like that by just whacking the crank.
Will be interesting to learn whether a bearing shell can fail with a pattern like that by just whacking the crank.
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Re: Weird pattern on rod bearing
Looks like impact/compression fracture. Rod is probably bent as well.
Re: Weird pattern on rod bearing
Looks like a piece of debris from when it was put together...and as it was rotated during assembly or initial cranking, it moved (looks like a slow movement) Then either imbedded itself or wore down and got washed away with the oil.
Don't look like it had anything to do with the overheating
Don't look like it had anything to do with the overheating
Re: Weird pattern on rod bearing
If foreign object damage, hard for me to believe it wasn't there when the engine was assembled.
Monty Frerichs
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Re: Weird pattern on rod bearing
a piece of plastigauge left in there. started to rotate with each compression stroke until it was linear with crank rotation at which point it ceated the rotational groove until it finally vanished.
Re: Weird pattern on rod bearing
Don't seem like plastigage would be tougher than bearing material. Definitely not able to leave a circumferential groove like shown.
Monty Frerichs
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Re: Weird pattern on rod bearing
Plastigage is oil soluable and will not cause damage if left in place when the engine is fired up.
Bill
Perfect Circle Doctor of Motors certification
SAE Member (30 years)
ASE Master Certified Engine Machinist (+ two otherASE Master Certifications)
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Perfect Circle Doctor of Motors certification
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ASE Master Certified Engine Machinist (+ two otherASE Master Certifications)
AERA Certified Professional Engine Machinist
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Re: Weird pattern on rod bearing
Something harder than plastigauge maybe, but other than that, my exact thought too.408swinger wrote: ↑Tue Oct 30, 2018 7:21 pm a piece of plastigauge left in there. started to rotate with each compression stroke until it was linear with crank rotation at which point it ceated the rotational groove until it finally vanished.
Re: Weird pattern on rod bearing
What does the crankshaft look like??? It should be scratched up. Picture please.
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Re: Weird pattern on rod bearing
Never saw the crank, was told it looked fine
From what I understand at this point from the customer this engine is back together and running.
No telling what will happen from here but its all out of my hands as I only saw the heads and the rods/pistons.
I tried to convince them to bring me everying to check it and clean it but he did not want to pull the engine down the rest of the way or spend anymore money on it.
I sent a bunch of pictures to the bearing manufacturer and have not recived any more info from them.
My thoughts on it were either damage during assembly which caused some delamination and wash out or damage from some debris in engine from improper cleaning or during assembly.
Also after closer inspection of this and the rest of the bearings it actually appears that this is a lower bearing and not the upper as I was told, the reason I feel that way is from the corner/edge damage to the other shell that looks like it was banged on the rod journal from the rod not going in square and straight when it was assembled.
Either way it has been an eye opening experience for the customer as to what you find when you open up a high volume reman engine.
Andy