350 SQUEAKING

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swump_man
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350 SQUEAKING

Post by swump_man »

I HAD ONE PISTON BREAK A PIECE OFF AND LOSE COMPRESSION. I HAD THE HEAD CHECKED AND THE OIL PUMP CHECKED. I ALSO REPLACED THE PISTON, ROD, WRIST PIN, AND NEW ROD BEARING AND REINSTALLED. I ALSO HONED THE CYLINDER. AFTER CRANKING IT IT NOW HAS A SQUEAK SQUEAK TO IT. ANY IDEAS???
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Slidin Gator
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Re: 350 SQUEAKING

Post by Slidin Gator »

In order of likelihood, probably a belt, idler, harmonic balancer, alternator, water pump. Squeaks would be really high pitched/fast if it was related to crank/short block, you would describe as a whine.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.
Gary S
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Re: 350 SQUEAKING

Post by Gary S »

Years ago I had a 327 I built for a pickup truck. It had a weird squeak to it. A year after I built it,it broke a piston skirt off a piston. I put a new piston in it and went on. One year later same thing happened. This time I checked the bore and found that when it was bored they had squeezed the bottom of the bore slightly and it would take a year to break the skirts off.
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Deano
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Re: 350 SQUEAKING

Post by Deano »

Gary raises an interesting point.
When I read your description, I initially figured you were referring to a ring land when you mentioned compression.
Hence, my following thought was that it sounds like detonation, in which case the other seven had been exposed to the same scenario.

Where did the piston break? If honing addressed the issue, Gary's premise likely does seem more feasible.
Any more you can share about where it broke and the history of the engine could only help.

Not to imply I disagree with Slidin Gator; I'm all for max optimism, but I can't help wondering why the one broke.
There is quite a bit that we don't know that could have a bearing on the initial cause and/or subsequent aftermath.
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but it is not the path to knowledge; it has no place in the endeavor of science."
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SWAMPHUNTER45
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Re: 350 SQUEAKING

Post by SWAMPHUNTER45 »

The piston that broke can you post a few close up pictures of it ?

Without seeing it and going off translation it would be hard to find a causation.

Cylinders over time will also wear in an egg shape and as the piston travels in the bore they can under combustion forces experience side pressures. With the Old Caddys it is something I have seen.

With pistons and detonation as Deano spoke of we need to see the piston and look for spalling or other evidence of a cause for fail.

Did you measure your rod clearances or just install a new bearing? Was breakin lube, STP or some assembly lube used on your new bearing surface and was the engine primed before you started turning it over? Have you fired it up or are you just spinning it with the starter?

Did you retain the rod bearings? I would want to see pics of them also

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swump_man
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Re: 350 SQUEAKING

Post by swump_man »

The piston broke on top above the first ring about a third of the way around the top. the engine was machined by a reputable machine shop and rebuilt. i ran the engine with direct drive for about 6 hours. i changed to belt reduction. i disconnected the belt assembly to rule it out and no change. ill try to get some pics posted. thank you!!
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Slidin Gator
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Re: 350 SQUEAKING

Post by Slidin Gator »

Was it Squeaking before you added the belt drive?
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.
Gary S
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Re: 350 SQUEAKING

Post by Gary S »

The machine shop that I used was in Homestead for years and had good reputation. The pistons I had break was the skirts. Broke from oil ring down.
barhopper
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Re: 350 SQUEAKING

Post by barhopper »

Slidin Gator wrote:
Fri Apr 09, 2021 6:39 pm
Was it Squeaking before you added the belt drive?
That is the big question
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Re: 350 SQUEAKING

Post by barhopper »

Slidin Gator wrote:
Fri Apr 09, 2021 6:39 pm
Was it Squeaking before you added the belt drive?
That is the big question
SWAMPHUNTER45
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Re: 350 SQUEAKING

Post by SWAMPHUNTER45 »

Top area if no interference generally points to ring gap clearance or detonation.

Look for spalling on piston top and I would want to see the rod bearings.

Was the piston that broke on a corner (1,2,7 or 8) of the engine?
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