| [GMCnet] ATF Leak at Transmission Pan (or chain cover?) [message #307052] |
Mon, 12 September 2016 13:50  |
fbhtxak
Messages: 191
Registered: April 2006
Karma: 0
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Thanks, Charles -
'Have done that as part of process of defining source of leak (in addition
to "diapering...).
Any thoughts on the chain cover?
There is no evidence of exterior "run-down" at chain cover/case interface...
'Regards,
Fred
Fred Hudspeth
1978 Royale (TZE 368V101335) - Tyler, TX
1982 Airstream Excella (motorhome) - Cooper Landing, Alaska
('Sorry - forgot to add above to earlier post)
Message: 11
Date: Mon, 12 Sep 2016 12:25:53 -0600
From: Charles Boyd
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] ATF Leak at Transmission Pan (or chain cover?)
Message-ID:
Content-Type: text/plain; charset="utf-8"
Brake cleaner and wipe dry. Spray baby powder on suspected area. Start it
up. Round the block maybe.
fbhtxak wrote on Mon, 12 September 2016 14:14
> I have isolated the source of the leak to the right rear corner of the pan
> (as seated in the driver seat). 'Have "diapered" all case penetrations to
> insure that no ATF is coming from them. 'Have tried many different pan
> gaskets over the years (and gasket sealants) but none completely stops the
> leak. The gasket that appears to work the best is a NAPA # 14525. Emery
> Stora reports using this gasket with good success. I installed that gasket
> during the last service about 6K miles ago.
>
> The NAPA gasket controls the leakage to about 1/2 pint (measured from a
drip
> pan) over several months of non-use.
>
> There is no leakage when traveling (as observed from no blow-back onto a
> clean, oil-free underbody).
>
> There does not appear to be a problem with the integrity of the
> transmission case or pan at the leak location.
>
> I have been unable to convincingly rule out the chain cover as the source
of
> (or contributor to) the leak. If mine is leaking, the source would be from
> just above the pan/case interface location stated above.
>
> Thoughts on proving(or disproving) the chain cover as the source of the
> leak?
>
> Also, thoughts on why the pan still leaks (if not from the chain cover)
> despite my attempts with a variety of gaskets (and sealants applied to the
> gaskets) to stop it.
>
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| Re: [GMCnet] ATF Leak at Transmission Pan (or chain cover?) [message #307068 is a reply to message #307052] |
Mon, 12 September 2016 18:25  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Just the other day Manny pointed out one area on the pan flange where
there's only about 1/16"-3/32" of overlap between the pan and the housing.
That's where he finds most leaks. All he offered for a solution is use of
Aviation Permatex on the pan and a cork gasket. Sounds like your source
and solutions you've tried. Perhaps it's time to consider modifying the
pan in that area? I'll try to look at one here tomorrow to see if I can
visualize anything that might work.
Ken H.
>
> fbhtxak wrote on Mon, 12 September 2016 14:14
>> I have isolated the source of the leak to the right rear corner of the
> pan
>> (as seated in the driver seat). 'Have "diapered" all case penetrations to
>> insure that no ATF is coming from them. 'Have tried many different pan
>> gaskets over the years (and gasket sealants) but none completely stops
> the
>> leak. The gasket that appears to work the best is a NAPA # 14525. Emery
>> Stora reports using this gasket with good success. I installed that
> gasket
>> during the last service about 6K miles ago.
>>
>> The NAPA gasket controls the leakage to about 1/2 pint (measured from a
> drip
>> pan) over several months of non-use.
>>
>> There is no leakage when traveling (as observed from no blow-back onto a
>> clean, oil-free underbody).
>>
>> There does not appear to be a problem with the integrity of the
>> transmission case or pan at the leak location.
>>
>> I have been unable to convincingly rule out the chain cover as the source
> of
>> (or contributor to) the leak. If mine is leaking, the source would be
> from
>> just above the pan/case interface location stated above.
>>
>> Thoughts on proving(or disproving) the chain cover as the source of the
>> leak?
>>
>> Also, thoughts on why the pan still leaks (if not from the chain cover)
>> despite my attempts with a variety of gaskets (and sealants applied to
> the
>> gaskets) to stop it.
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] ATF Leak at Transmission Pan (or chain cover?) [message #307257 is a reply to message #307068] |
Fri, 16 September 2016 22:54 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Fred, et al,
I've checked out that right rear corner of the transmission oil pan where
so many seem to have leaks. It really is a very narrow seating surface --
about 3/32" at most. Trouble is, I don't seen any simple improvement. It
might be feasible to braze the inside of the pan up enough to add 1/8" or
so of surface, but the pan and its flange might be warped enough to either
worsen, or not improve, the situation. One who REALLY trusts JB Weld or
similar epoxy putty might build up that area enough to help -- but I don't
know what the long term durability of epoxy is in ATF.
Sorry I can't really suggest anything useful. :-(
Ken H.
On Mon, Sep 12, 2016 at 7:25 PM, Ken Henderson
wrote:
> Just the other day Manny pointed out one area on the pan flange where
> there's only about 1/16"-3/32" of overlap between the pan and the housing.
> That's where he finds most leaks. All he offered for a solution is use of
> Aviation Permatex on the pan and a cork gasket. Sounds like your source
> and solutions you've tried. Perhaps it's time to consider modifying the
> pan in that area? I'll try to look at one here tomorrow to see if I can
> visualize anything that might work.
>
> Ken H.
>
>>
>> fbhtxak wrote on Mon, 12 September 2016 14:14
>>> I have isolated the source of the leak to the right rear corner of the
>> pan
>>> (as seated in the driver seat). 'Have "diapered" all case penetrations
>> to
>>> insure that no ATF is coming from them. 'Have tried many different pan
>>> gaskets over the years (and gasket sealants) but none completely stops
>> the
>>> leak. The gasket that appears to work the best is a NAPA # 14525. Emery
>>> Stora reports using this gasket with good success. I installed that
>> gasket
>>> during the last service about 6K miles ago.
>>>
>>> The NAPA gasket controls the leakage to about 1/2 pint (measured from a
>> drip
>>> pan) over several months of non-use.
>>>
>>> There is no leakage when traveling (as observed from no blow-back onto a
>>> clean, oil-free underbody).
>>>
>>> There does not appear to be a problem with the integrity of the
>>> transmission case or pan at the leak location.
>>>
>>> I have been unable to convincingly rule out the chain cover as the
>> source
>> of
>>> (or contributor to) the leak. If mine is leaking, the source would be
>> from
>>> just above the pan/case interface location stated above.
>>>
>>> Thoughts on proving(or disproving) the chain cover as the source of the
>>> leak?
>>>
>>> Also, thoughts on why the pan still leaks (if not from the chain cover)
>>> despite my attempts with a variety of gaskets (and sealants applied to
>> the
>>> gaskets) to stop it.
>>
>
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http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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