<VV> Broken Engine- A true Story... Not Speculation

[Mike Mauro]

<Snip>...For you analytical types, I guess it might be intriguing to figure out what
the specific problem is before you remove the head (escaping air here means
this and escaping air there means that), but you are still going to end up
removing the head.  So, just DO IT and FIND the problem....<Snip>

I've been working on Corvairs for well over thirty years... I don't know about the rest of you' all, but the luster of working on cars has dulled a bit in my world.  My preference of using a leak-down test, before head removal, is based upon a desire of NOT having to do work over, unnecessarily.  Case in point:  Just recently, the wife's Greenbrier was not idling quite right, so, as part of my normal tune up routine, I performed a standard cranking compression test.  #1 cylinder came up to 110psi, while all the rest pumped up to a respectable 150-to-160.  Further testing, after adding several ounces of motor oil to the offending, #1 cylinder, showed only a marginal improvement in that cylinder's cranking compression performance (went up about 5psi).  Traditional logic pointed to something going on with the valves:  the engine had been using just a little above average amount of oil, but not extreme, and absolutely NO smoke.  First inclination....just pull the heads and do a valve job.   However, went a step further: during a subsequent  leak-down test, SOME air could be heard from both the carb and the tail pipe (supporting the pull the heads only theory), but an even larger quantity of air could be heard coming from the oil fill spout.  Upon tear down, found #1 upper compression ring broken.  The cylinder wall looked normal in every way.  There is no way that just pulling the heads would have shown the real problem (and doing a leak-down test is a lot easier than pulling the jugs with engine still in the vehicle).  Had I not taken the time to perform the leak-down test, I would have just done a valve job, and, then, when the vehicle still did not idle properly, I'd have been right back at it, cussing myself for not doing more complete diagnostics (been there, and learned from it).
Cheers,
Mike Mauro