Not to forget that too many people over-apply silicone sealer and it
squeezes into the crankcase/heads, breaking loose to clog oil passageways
and fry a rod bearing.
I'm with you- I never apply anything to O-rings - think of this: it did'nt
come all gooped up with silicone from the factory.

Robert

1982 Westfalia

----Original Message Follows----
From: "G.M.Bulley" <gmbulley@BULLEY-HEWLETT.COM>
Reply-To: "G.M.Bulley" <gmbulley@BULLEY-HEWLETT.COM>
To: vanagon@GERRY.VANAGON.COM
Subject: O-Rings, was: rebuilder blames coolant for failure under warranty
Date: Tue, 14 Jan 2003 12:20:24 -0500

I'm not sure if you guys are joking about putting sealant on o-rings,
but if any of you are, I'd strongly urge you to read up on how o-rings
work. They are perfect in their simplicity, and rely completely on
absolute cleanliness, and absolutely no other material in their sealing
zone.

I'd be up their with Bill Gates if I had a dollar for every type-4 I
found with leaking push-rod tubes seals, only to find RTV or 'high-tach'
sealant on the o-ring seals. Since the type 4 motor gets wider as it
heats up, the heads must be able to move in and out, and the o-ring
bores (for the pushrods) are about 2mm wider than they need to be (at
rest) so the rings can roll as the heads move. Clog up that 2mm with
goop, and they won't roll, and they leak within 50k miles.

The pressure of oil behind an o-ring causes it to seal better as the
curve of the ring is flattened under the pressure. If the oil can't get
behind the curve of the ring (again because of RTV) you get leaks.

Were you joking?

Bringing ideas to life,
G. Matthew Bulley
Bulley-Hewlett
www.bulley-hewlett.com
AIM = IExplain4u
+1.919.658.1278
"Fax mentis incendium gloria culpum"

Robert
1982 Westfalia 1987 Wolfsburg

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