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What are the running characteristics of broken piston rings?

Is there a noticeable symptom that indicates a broken piston ring?
What is it? Generally, which ring is prone to break, top, middle, or oil control ring?

Old 01-29-2004, 11:28 AM
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I was just dicussing stuff like this with Tyson at TRE this morning. It seems to me a leak down might divulge issues like broken rings, but even that isn't definitive.

Loss of oil perhaps? Smoking on decel? Is anything like that occurring?
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Old 01-29-2004, 11:31 AM
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Great question, movin. I'd be interested in the answer. You might also want to post this on the 911 Engine Rebuilding forum.
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Old 01-29-2004, 12:28 PM
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Cool

only guessing,
top piston land gets worn. so I figure the top ring is more likely to break.
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Old 01-29-2004, 12:58 PM
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Off the top of my head, a low compression test reading might be an indication and/or increased blowby.

Sherwood
Old 01-29-2004, 01:21 PM
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Old 01-29-2004, 01:27 PM
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I had detonated /overheated the top ring, piston lay, and 2nd piston ring on my #1 and the top ring on #2 cylinders on a '73 2.7 motor before.

It smoked REALLY REALLY bad.... On acceleration more than decelleration.

Good luck.
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Old 01-29-2004, 01:38 PM
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An oily spark plug.

Pull your plugs and have a look. It is a good indicator of this problem.

John
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Old 01-29-2004, 03:02 PM
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I just had this happen to the corvair. Biggest clue was excessive oil consumption. Increased crankcase pressure, and NO compression in #6. Complete disassembly revealed both compression rings were broken and managed to scar the cylinder wall pretty good.
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Old 01-29-2004, 03:50 PM
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Yeah, it's using oil (500mi/qt), but like others smokes a little at start-up then settles down, smokes a little on acceleration, and accumulates a light brown film on the valence around the exhaust pipe after about 1000mi. I don't really see hardly any smoke and looking at the plugs there's no indication anything is wrong, it's like the oil is being spit out of the exhaust ports. If I drive it hard the oil consumption goes up (400mi/qt). Could oil be sucked down the exhaust guides? If so then during positive pressure the oil is blown back up into the cam towers, and during evacuation/low pressure it's being sucked into the exhaust ports?

Old 01-29-2004, 06:51 PM
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