This is a timely discussion for me. I removed my adapter a couple of
weeks ago to have the block boiled out and rebuild the engine. The
gasket on my adapter looked like a square rubber seal (maybe from and
oil filter) and it was torn. Does anyone have the specs or source for a
replacement "O" ring? Is the Ford # Tom mentioned the right one?
Craig Wright
Steve Laifman wrote:
> O-rings:
>
> How they are supposed to work, and why they sometimes fail. The
> results of my participation in our own and the Shuttle mishap on
> O-rings engineering design practice, and the modes of failure.
>
> 1) O-rings are round in cross section, which is why they are called
> "O" rings.
> 2) There are other rubber seals, even of the same materials, that are
> NOT round, and do not physically function in the same manner as an
> O-ring.
> 3) An example of such a seal is right on the end of most oil filters.
> The seal is a rectangular, or square cross section rubber like
> (neoprene, typically) material. As are O-rings. But these are
> crimped in place on three sides, and a small amount sticks out as the
> sealing face against a machined surface. The crimping physically seals
> three of the sides, and the compression against the block, or holder,
> the first pressure seal. There is no dynamic energization as a result
> of increasing pressure, as an O-ring design. It is strictly a
> compression seal, like your head gasket and valve cover.
> 4) The TRUE O-ring is designed in accordance, at least in military and
> commercial applications, against JANNAF (Joint Army, Navy, Air Force)
> standards. The dimensions of the o-ring groove, relative to the
> application, the clearances between the walls and the o-ring, the
> compression forces, an the amount of pressure it is rated at, along
> with the temperature operating range are variables in the design and
> result in a different product.
>
> Typically, the O-ring is in a square groove, and does NOT fill the
> groove. It is sealed at the low and high pressure side operating on
> opposite sides of the ring, and groove, "across" the top. -|_O_|-
> (close as I could get, imagine a top that squeezes the o-ring, but
> does not touch the opposite metal.
>
> The instant pressure is applied, the true o-ring physically moves
> across the o-ring groove and the pressures try to force it out the
> small gap on the low pressure side. Of course it gets squeezed into
> that groove "gap" harder, the more the pressure increases, sealing all
> the harder. Which is why it is a good design.
>
> It can be "killed", of course, by poor material choices, incorrect
> clearances or clamping forces, damaged grooves or rings, environmental
> extremes beyond design parameters.
>
> Most of you know about the Shuttle disaster. This 3 back-up ring
> design was based upon the very successful Titan rocket design with
> only one O-ring in each 10 foot DIAMETER joint, sometimes 7 on each
> side of each launch. In the shuttle case, only one parameter was not
> adequately monitored, the O-ring material temperature. It was so cold
> on launch day that icicles were hanging from the joints.
>
> Need you imagine just how flexible these huge rings were when they
> were so cold. On energization, they simply did not have the plasticity
> to deform around the groove opening, and seal tighter the harder it
> was pushed. It leaked, just a little. Well, a little leak of 6,000
> deg gases does not bode well for a rubber ring.
>
> So, how does this relate to Tigers.
>
> Here is how. If you do NOT have a SQUARE o-ring groove, you cannot
> use an O-ring. The FoMoCo 6880 had such a groove between the adapter
> and the block (flat surface), and does use an O-ring for this seal.
> The O-ring does NOT fill the groove, per design practice, and does not
> leak. The gasket on the filter is a 3 sided captured square rubber
> seal, not an o-ring, and also does not need another gasket. There is
> another O-ring on the enter holding bolt for the block mount.
>
> Older right angle adapters did NOT have O-rings, and relied on flat
> surface seals, much like your head gasket or valve cover.
>
> Well, you wanted to know about O-rings. Those were the opening
> remarks of the tech eval team on the first day. 4 months later, we
> REALLY understood the issue.
>
> Steve
>
> Tom Witt wrote:
>
>> I know that this has been touched on before and that Jim Boynton has an
>> article relating to the matter at Tigers United, but my problem has a
>> bit of a
>> twist. My oil filter adapter (part # E5TE-6884-BA) came off a late
>> 70's thru
>> early 80's Ford Van. The O-Ring slot is square cut. The van this came
>> off of
>> simply had a similar sized round O-Ring with silicone put on it. I
>> went to the
>> dealer (taking the adapter) and asked for the proper replacement. I
>> was given
>> (without looking anything up) a very thin, round O-Ring FCM 87147S91
>> and was
>> told that "it would work." I questioned the fact that the O-Ring was
>> so thin
>> (and round), and that it slopped around in the square groove, but was
>> told "it
>> would work."
>> Well, after I bought it ($4.59 at Ford, O-Rings everywhere else --- .99
>> cents) I still had my doubts and opted not to use it. To add insult
>> to injury
>> my wife took it back while out shopping and Mr. Parts Expert "it will
>> fit"
>> wasn't bright enough to refund her the $4.59, but instead gave her
>> back $1.43
>> on the fiber washer price! I know it's only three bucks, but it is
>> the point
>> that counts. As far as I'm concern this guy has now made two mistakes
>> on a
>> simple transaction. So that I might properly correct "Mr. Parts
>> Expert" could
>> anyone tell me if the Ford Motorsports oil filter adapter has a
>> square cut for
>> the O-Ring and if, in fact the O-Ring itself is square(ish). From
>> what I can
>> see in the pictures it appears to be and I suspect that the
>> FMS-M6880A50 might
>> be what I need.
>>
>> By the way, is it just that I'm a walking crash test dummy for
>> Murphy's law
>> or do you, like my wife and I, find it takes the time of nearly an
>> eight hour
>> day each and every week just to correct for people unable to do their
>> job
>> properly. I know that we all make mistakes, but for us this nonsense
>> happens
>> ALL the time.
>>
>> Tom Witt B9470101
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