Manual Transmission Fluid Change - Photos???

it's not just a tendency, plastic deformation is the primary function in
order to seal effectively.

not so. with hard materials [springs], you'd have to deform the material
around the washer in order to seal, not have the washer deform to fit its
surroundings. one method has a long term future, the other, not.

to a limited extent, sure. but unlike a typical shop situation where the
vehicle operator never sees [not cares] about what's under the hood, much
less whether a drain plug gasket is leaking, i inspect. if it's leaking,
it'll get replaced. if it's not, it won't. that actually has less risk
that using a new washer and not inspecting!

again though, i reemphasize, the big temptation with seal washer re-use is
to over-tighten. that's a HUGE no-no.

 

We disagree. The sealing material to use (springy or not
blah blah) depends on the application.

 

with respect elle, copper or aluminum crush washers are not springy.
their sole purpose is to deform [and thus conform] to surface anomalies
and so, create a seal. hard materials simply don't do that - which is why
they're not used!

 

Well, I just called my parts guy and gave him those two numbers
(94109-20000 and 94109-14000). He immediately recognized both numbers and
knew they were for the oil pan and transmission. He even has them in stock.

Apparently several models use those parts, not just the Civic and Integra.

I do remember now that getting a /drain/ bolt washer was never a problem,
just the one for the /fill/ bolt.

It's been at least ten years since I last asked him for the fill bolt
washer, and he no longer remembers our previous difficulty in finding it.

I'm going to pick up a few of each next time I'm down there.

Thanks for your help.

 

I think we are talking past each other. I am saying that,
generally speaking, some sealing materials are in fact
rubber or similar and so are springy. Other sealing
materials work by plastic deformation. Which is used
depends.

 

it's hard to reliably use just a rubber seal under a screw because it's
difficult to torque sufficiently to reliably retain the screw. [ever had
to re-torque a leaky oil pan? usually, /all/ the screws are loose.]

additionally, for drain plugs, as the shear of twisting commences as the
two sealing surfaces contact, it can tear. thus polymers are used for
gaskets, and copper or aluminum alloys are used drain plugs.

 

Toyota's OEM gasket for oil pan drain plugs is non-metallic. It's some sort
of hard black fibrous material. Works quite well.

 

it uses the fiber reinforcing to address tearing. and being polymeric, it
can't take the same thermal load - academic here though.

 

What does thermal load matter? The gasket works just fine sealing against
hot oil in spite of being non-metallic, which was my only point.

A gasket for a fastener does not have to be metallic to be effective and
allow specified torque.

 

I am talking about seals in general--oil pan gaskets,
o-rings, washers, etc.

 

to be utterly pedantic, a metal crush washer isn't going to soften or
creep at the temperatures a polymeric one will. and thus it will maintain
torque. academic? probably. relevant? probably not.

 

So then how is it that the Toyota fiber washer appears to maintain torque
sufficient to prevent leaks?

I have to give a fiber-gasketed bolt just as much of a tug to loosen it
that I must apply to a Honda metal-gasketed bolt, so clearly the fiber
gasket is not failing over time.

If you mean a fiber washer would not be able to withstand temperatures of,
say, 1000 degrees while a metal one will, that may well be true. Except
that oil never gets any hotter than about 220, so metal's advantage there
is moot.