Date: Thu, 29 Dec 2011 15:58:48 -0800
Reply-To: John Anderson <wvukidsdoc@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Anderson <wvukidsdoc@YAHOO.COM>
Subject: O-ring seals was Re: Tranny O-ring size
In-Reply-To: <087b01ccc67b$862090e0$6401a8c0@PROSPERITY>
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Scott, respectfully and I mean that, you always have good opinions. BS.
I designed O-ring seals amongst other things there in the 90's for several years from low pressure up to 10,000 psi. A lubed O-ring (silicone grease almost always a good choice) installed in a properly designed setting (anything VW intended) will seal optimally without any sealant. In fact Parker, Apple, any of the big names will state in their design guides that O-ring seals will often NOT WORK at all in a long term sense, as intended with a sealant applied. The O-ring does not work goobered up with a semi-solid sealing material. It is supposed to be able to move in its land, goob up the land, it doesn't function any more than a solid goob of RTV glue would in the same spot (which might admittedly be just fine.) O-rings rely on well finished mating surfaces, in proper approximation, with proper stretch of and crush on a properly chosen (durometer and material) O-ring. New in nearly any automotive setting, all of these were present in
todays world (last 40 years) as O-ring seal design is a well, well, hammered out engineering thing until you get to real high speed, high pressure, or high heat situations. The illusion that a sealant solves problems, is that it solves problems based on a degradation of one of the design factors. If the parts are still in good shape, not corroded, not scored, the lubed O-ring alone will give the same service when replaced (to solve the change in durometer as it aged) that it did when new. Which in the case of the one on the governor of an autobox if he cleans the surfaces well will probably be a solid 15+ years as they aren't usually corroded, and it don't move so there is no wear at the seal that would require a sleeve, or metal deposition, or the things one uses to cure a leaking O-ring seal.
Anyway gouge the surface, have corrosion, wrong material O-ring for the job, whatever it is doomed to fail, and yes goobering it up with a good quality RTV (I prefer the clear MBZ stuff that Karl put me onto years ago) will give the illusion the problem is solved. But as you imply, you might have just as well left the O-ring out, and just goobered it up, cause excepting the fact that it is centering the male in the female part, it ain't doing shit.
Sorry but this one has always burnt me up, wrote a treatis involving it on T4 pushrod seals on this list near 15 years ago, and it still applies today. You will NEVER see a hydraulic shop at least one of any quality using sealant on any O-ring seal, and they are probably the most common use secondary to automotive. You restore the surfaces, if you can't anything short is a rig.
To the OP, if you got somebody with a universal nitrile O-ring set you might come up with something close, but as Scott does state, probably not. It isn't going to cost more than a buck or two even from the dealer (probably a fancy graphite impregnated one now) if it isn't NLA, and being an O-ring it probably isn't.
John
----- Original Message -----
From: Scott Daniel - Turbovans scottdaniel@TURBOVANS.COM
I never put an o-ring in dry ..or just lubed.
they will always leak later without a sealant as well.
scott
turbovans.com
----- Original Message -----
From: "marc rose" <mrose1028@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, December 29, 2011 12:24 PM
Subject: Re: Tranny O-ring size
> Forgot to mention it is an 90 Carat 2.1 with auto tranny.........mt bad.
>
> On Thu, Dec 29, 2011 at 12:13 PM, marc rose <mrose1028@gmail.com> wrote:
>
>> This is my first time posting and I am a new Vanagon owner also.......It
>> looks like the o-ring around the governer cap is leaking fluid and I was
>> wondering if anyone knew what the correct size of o-ring is?
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