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Does this look like too big of a gap on my old to compression piston ring?

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It measures more than 0.04" (I stacked a 0.02 and a 0.021 feeler gauges together) but I could not find a specification for an acceptable range in my Haynes manual for my Toyota Tacoma v6 2007. By searching the web, I found that it should be around 0.004" per inch of bore diameter, which in my case is 3.6", so 3.6 x 0.004 = 0.0144". So I am about three times that much, assuming that threshold is correct.

Q1: Does this explain why my pistons were leaking almost 100% of air pumped in?

Q2: How did the gap widen so much? It started leaking (losing compression) only after moisture/ice got into the cylinders when I had the heads off last winter for a valve grinding job.

RELATED: Likelihood of every piston ring corroding the same rate

amphibient
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1 Answers1

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The best way to know the end gap clearance is to consult a service manual for your vehicle. But the rule-of-thumb is 0.004 x the bore diameter in inches.

You're way over that and this is a problem.

  1. Check your piston bore to make sure it's within specs.
  2. It's quite possible that your ring is damaged from the earlier event with water/ice.
jwh20
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