Help - The Bomb

Bernie Benz b.benz at
Fri Sep 5 10:03:44 EDT 2003

> From: Phil Rose <pjrose at>
> At 7:07 PM -0700 9/4/03, Bernie Benz wrote:
>>> From: "Derek Pulvino" <dbpulvino at>
>>> ...thusly maybe Pentosin is adequate as a lube.
>> With luck, your in.
> Bernie has me reconsidering the o-ring "lubrication" issue.  He
> believes that "Pentosin is not enough", and that's something I'll try
> to remember the next time I find myself doing this job.
Maybe I was being too outspokenly forceful (who, me?) with that quoted
statement.  Better said:  Pentosin may not always be a sufficient lubricant
to prevent O-ring distortion.  Using an EP oil, graphite grease, or whatever
else is open on the bench as the O-ring lub, I've never experienced a cyl
head O-ring failure, with Pentosin or my current tractor hydraulic oil in
the system.  I do like your chicken soup idea!

> Why? Well, like Derek and most others, I routinely use Pentosin to
> lube the new o-rings during installation. However--even though that
> procedure generally seems to avoid the major distortions responsible
> for rapid recurrance of leakage--it is all too common for leakage to
> recur within just a few years. I've always thought that this rather
> short o-ring lifetime was primarily a matter of shrinkage and/or
> hardening of the rubber (from the high-temperatures and possibly from
> chemical interactions between the rubber and Pentosin.) However, I
> now wonder if of some degree of o-ring stretching (even a small
> amount) during installation might contribute to significant reduction
> of seal effectiveness (i.e., lifetime). I realize that's pure
> speculation, however I think it's plausible enough to warrant the
> precaution of applying a better (better than Pentosin) lube to the
> o-rings.
> Like the chicken-soup remedy--it couldn't hurt. (no, I don't advocate
> using chicken soup on the o-rings).
> Phil
> --
> Phil Rose
> Rochester, NY
> mailto:pjrose at

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