Leaking A/T Pan

[charles w aulgur]

Neely Butler,

Before you go to the trouble of changing your A/T gasket, you may want
take a good look at the pan to see if the oil is seeping through the
aluminium material. I experienced the same leaking problem several years
back, and after trying three different types of gasket material and
silicone, I finally took a closer look as to where the oil was coming
from. It was seeping through the pours in the aluminum material and
caused "wetting" on the outside of the pan same as a leaking gasket would
cause. Some types of aluminum used in castings are very porous and have
to be "sealed" to keep them from leaking oil. The automotive industry
seals all of their aluminum castings that are used in places that have to
contain oil. They are sealed with sodium silicate "water glass" in a
vacuum oven at elevated temperatures. I have been told that one type of
aluminum A/T pans being sold for our GMCs are not sealed in this way.
They cannot be sealed after they have been subjected to oil. You may
have to return your pan and try another one or go back to the OEM pan.

Chuck Aulgur-76 Royale-CA

 

[neely butler]

Chuck,
Thank you for your reply, I think the problem has been solved. Mechanic
says leak is from speedometer cable where it is connected to transmission.
He says it needs new washer like "o" ring. Thanks again
Neely B, TN
- -----Original Message-----
From: Charles W Aulgur
To: gmcmotorhome
Date: Saturday, March 25, 2000 10:03 PM
Subject: GMC: Leaking A/T Pan

>Neely Butler,
>
>Before you go to the trouble of changing your A/T gasket, you may want
>take a good look at the pan to see if the oil is seeping through the
>aluminium material. I experienced the same leaking problem several years
>back, and after trying three different types of gasket material and
>silicone, I finally took a closer look as to where the oil was coming
>from. It was seeping through the pours in the aluminum material and
>caused "wetting" on the outside of the pan same as a leaking gasket would
>cause. Some types of aluminum used in castings are very porous and have
>to be "sealed" to keep them from leaking oil. The automotive industry
>seals all of their aluminum castings that are used in places that have to
>contain oil. They are sealed with sodium silicate "water glass" in a
>vacuum oven at elevated temperatures. I have been told that one type of
>aluminum A/T pans being sold for our GMCs are not sealed in this way.
>They cannot be sealed after they have been subjected to oil. You may
>have to return your pan and try another one or go back to the OEM pan.
>
>Chuck Aulgur-76 Royale-CA