Home » Public Forums » GMCnet » Transmission Oil Pan Leakage Problem 2
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| Re: Transmission Oil Pan Leakage Problem 2 [message #204972 is a reply to message #204968] |
Wed, 17 April 2013 15:58   |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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John,
I had the exact same problem with my Rockwell transmission pan. For the life of me, I couldn't get it to stop leaking. Never had a problem with the stock pan and a dry gasket. I tried two different gaskets and had it apart four times. Frustrating to say the least.
I finally got it down to what you have, leaks around the bolts. Even that does not make sense, because the bolt holes are completely surrounded by gasket material. I did something similar to what you did, only I used O-rings around the bolts. That worked pretty well, but I finally ended installing SS flat washers with RTV sealant on them. It STILL leaks a little bit, but it will have to wait until my next transmission fluid change before I tackle it again.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Transmission Oil Pan Leakage Problem 2 [message #205029 is a reply to message #204972] |
Thu, 18 April 2013 00:13 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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are they flat at the holes or is there some flashing or burrs around them? You may be able to eliminate this by taking a sharpening stone across the holes to hone down any rough spots that may be preventing proper gasket compression.
Tranny fluid is like Hydrogen. It leaks out of everything!!!
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: Transmission Oil Pan Leakage Problem 2 [message #205030 is a reply to message #204968] |
Thu, 18 April 2013 00:14 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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If you have the pan off, go over the surface with a straight edge looking for any defects in machining.
If you actually have oil leaking down the bolts and the gasket looks OK, I would put o-rings on all of the bolts (threaded end) prior to re-installing the pan.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Transmission Oil Pan Leakage Problem 2 [message #205037 is a reply to message #204968] |
Thu, 18 April 2013 02:01 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Good Points!!
My Unit is still in storage. (We still have snow on the ground in Edmonton!!) I have not been able to actually look at the transmission pan mounting on the case of the THM425. Does anyone have pictures or have a empty case they can have a look at for me please? (I could not find any pictures myself) I've made a quick drawing of 3 different ways that pans, or other things, are mounted to cases.(Not just transmissions)
http://www.gmcmhphotos.com/photos/discussion-photos/p48694-tranny-bolts.html
(I've seen them all) In fact the water pump bolts (Bottom 2)that are threaded into the timing cover plate is the same as illustration "B". These bolts need to be sealed at the threads or there can be an oil seepage from those bolts. (could be mistaken for a front seal or front cover leak)
What I want to know is: Are there any bolts into the tranny case the same as "B"? If so, it may be my problem and the answer may simply be: putting sealer on the bolt threads.
Best Regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] Transmission Oil Pan Leakage Problem 2 [message #205075 is a reply to message #205037] |
Thu, 18 April 2013 09:44 |
Jp Benson
Messages: 649
Registered: October 2011
Location: Fla
Karma: 2
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Well John, that's an interesting question. Three sides of the trans have interior bolts. I don't know if it's B or C though. Will check when I install the new gasket. That will probably be next week. Nice pics.
Still, though, it seems most of the leaks are described as being at the rear.
JP
>________________________________
> From: John Heslinga <rbeeper@hotmail.com>
>To: gmclist@temp.gmcnet.org
>Sent: Thursday, April 18, 2013 3:01 AM
>Subject: Re: [GMCnet] Transmission Oil Pan Leakage Problem 2
>
>
>
>
>Good Points!!
>
>My Unit is still in storage. (We still have snow on the ground in Edmonton!!) I have not been able to actually look at the transmission pan mounting on the case of the THM425. Does anyone have pictures or have a empty case they can have a look at for me please? (I could not find any pictures myself) I've made a quick drawing of 3 different ways that pans, or other things, are mounted to cases.(Not just transmissions)
>http://www.gmcmhphotos.com/photos/discussion-photos/p48694-tranny-bolts.html
>(I've seen them all) In fact the water pump bolts (Bottom 2)that are threaded into the timing cover plate is the same as illustration "B". These bolts need to be sealed at the threads or there can be an oil seepage from those bolts. (could be mistaken for a front seal or front cover leak)
>
>What I want to know is: Are there any bolts into the tranny case the same as "B"? If so, it may be my problem and the answer may simply be: putting sealer on the bolt threads.
>
>Best Regards
>--
>John and Cathie Heslinga
>1974 Canyonlands 260
>TC4W "Too Cool For Words"
>Retirement Projects Galore
>Edmonton, Alberta
>_______________________________________________
>GMCnet mailing list
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| Re: [GMCnet] Transmission Oil Pan Leakage Problem 2 [message #205084 is a reply to message #205072] |
Thu, 18 April 2013 10:58 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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| Jp Benson wrote on Thu, 18 April 2013 07:30 |
I also had rear seepage from the Rockwell pan. The smallest leaf on my
feeler gage would not fit between the rear trans cover and the bevel on
the Rockwell pan. Upon removal of the pan there was fluid all across
the rear flange but no where else. I scored a line ~3/64" inside the
bevel then used an 18" belt sander with 40 grit then 120 grit for the
rough grind. Finished with 320 grit using an orbital sander. Grinding and polishing took about 5 minutes. The real work was recovering the fluid and R&R on the pan. Upon re-installation of the pan
(using the old gasket for fit test), there was a space of ~0.010"
between the bevel and the flange on the rear cover. I'm going to
install the new neoprene gasket and refill the pan.
Pics at http://www.gmcmhphotos.com/photos/g6355-rockwell-pan-mod.html
If it were bolt
hole leakage then why only on the rear?
I'm still debating on following Manny's very sound advice to use Permatex.
JP
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Nice job, JP. Hopefully I will remember to double check that when I do my next tranny oil change. I don't remember the clearance being an issue at that point when I did it in the first place.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Transmission Oil Pan Leakage Problem 2 [message #205154 is a reply to message #205037] |
Thu, 18 April 2013 20:08 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| John Heslinga wrote on Thu, 18 April 2013 00:01 |
... I've made a quick drawing of 3 different ways that pans, or other things, are mounted to cases.(Not just transmissions)
http://www.gmcmhphotos.com/photos/discussion-photos/p48694-tranny-bolts.html
(I've seen them all) In fact the water pump bolts (Bottom 2)that are threaded into the timing cover plate is the same as illustration "B". These bolts need to be sealed at the threads or there can be an oil seepage from those bolts. (could be mistaken for a front seal or front cover leak)
What I want to know is: Are there any bolts into the tranny case the same as "B"? If so, it may be my problem and the answer may simply be: putting sealer on the bolt threads.
Best Regards
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I have an uninstalled TH425 in my garage.
<http://www.gmcmhphotos.com/photos/craig-s-list-finds/p19399.html>
A quick look shows most are "A" (bolt hole outside the case), but a few look to be "C" (blind hole in the case), but without pulling the pan, it is hard to be sure they are not the dreaded "B" (bolt hole inside the case).
I do not have time to pull the pan right now... I have to go to work. 
If no one actually KNOWS already, I can take pictures later.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: Transmission Oil Pan Leakage Problem 2 [message #205182 is a reply to message #204968] |
Fri, 19 April 2013 00:03 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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Big Thanks for the information so far!! 
When I take the Oil pan off for a transmission service later this summer or early fall, I will make some of the same changes and also be sure that all surfaces are Flat, Smooth, and closer to Gasket shape. I was hoping that all I needed to do was use the drain plug and drain the oil and leave that pan on.
Some additional comments:
From the real poor pictures I have in a service manual, it is still not clear if any of the holes are Type B in my illustration. I can see there are many oil pan bolts that thread into the inside of the transmission case. What is not clear, on anything I can find, is if there is a boss cast into the bolt space to create a blind hole. Or if they are simply open in the case side. Some things I will also check for is: maybe a PO or I had used a bolt that was too long and broke out the boss??(If there is one there) The Rockwell pan came with three or four different bolt lengths. I followed the install information closely, and did not feel a lot of resistance and used 12 ftlbs torque, therefore I do not think I would have cracked them out (If that is the problem)
I noticed that Manny had stated in another thread that the heavy aluminium pan does not flex, therefore, the gasket has to have a wide range of compressibility to effectively seal any imperfections in the case and pan. The Permatex will increase the imperfection "fill-ability" of the gasket on the interfacing surfaces. The fact that I'm not getting any leaks through the "Pan - Case" interface makes me feel there are issues related to the oil pan bolt holes or the Transmission case bolt holes.
I also notice that on the inside of the pan there is a casting flash that runs radially around the pan about 1 inch below the gasket surface. Could it be that that may be a leak into the bolt holes of the pan. Or has there been a casting sand inclusion at that casting joint? Has anyone had any problems with that on their pans??
I'm still hoping someone has a open transmission case sitting around to be able to identify how it is cast around those inside bolt holes. (Not many of us will have one - I'm sure) If not: I will have to find out once I remove the pan.
Best Regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: Transmission Oil Pan Leakage Problem 2 [message #205189 is a reply to message #205182] |
Fri, 19 April 2013 01:50 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| John Heslinga wrote on Thu, 18 April 2013 22:03 |
...
I'm still hoping someone has a open transmission case sitting around to be able to identify how it is cast around those inside bolt holes. (Not many of us will have one - I'm sure) If not: I will have to find out once I remove the pan.
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I have a complete uninstalled "core" transmission. If no one else has investigated this before this weekend, (for me that is almost Monday) I'll pull the pan and take some pictures. (I might need an inspection mirror.)
I haven't opened it from the time I bought it a few years ago, and do not even know if there is any fluid in it.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: Transmission Oil Pan Leakage Problem 2 [message #205250 is a reply to message #204968] |
Fri, 19 April 2013 12:54 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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Thanks Mike!!!
Hopefully Manny will pipe in here somewhere. He must have a pile of Scrap cases outside his shop waiting to go to recycling.
When I was in Amana in the fall I noticed that Jim K. had 3 or 4 Rockwell Pans (old) that he had returned to him to bring back to California. I don't know what the problems of those were, but it certainly piqued my curiosity when the oil pan leakage subject was broached. I'm intending to go down the west coast for a car tour in the next couple of weeks and was wondering if I should also remove and bring my pan and go as far as San Francisco. Shipping and export / import charges of stuff to and from Edmonton adds so much to the cost of anything that “Just Fixing it” may be a better option.
I'm willing to measure, flatten, and machine what I can but that will have to wait.
If the problem is porosity I could coat the inside of the pan with Gyptol type paint to seal it from the inside. I’ve used Gyptol on Cast block porosity successfully in Non pressure areas and non sumps, but I am not sure how well it works with a sump of Aluminium and transmission fluid. I also do not really like the idea of paint and things that can flake inside an engine or transmission.. However many racers swear by it!!! But they do not use it in the sumps either.
I like the Pan! I think it is a good idea, and it looks Cool. But I know others are having a bit of problem with this pan and the Ragusa as well, and this is why I'm asking for help. The returned pans at Amana, my problem, the ones shared by J.P., R.F., and Carl are an indicator to me that there are some issues here that need resolution. If these cast type pans are subject to these leakage problems, Maybe we can create a number of solutions for all of us to refer to as we solve our particular problems . I've worked with Ford service a number of times before to resolve such maintenance issues and the resulting solutions are always shared through the bulletin system. Maybe these manufactures could put out a technical bulletin with these solutions as well.
With all or your input, I will solve my issue, but I would like to share that with everyone!!
My Thanks
and
Best regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] Transmission Oil Pan Leakage Problem 2 [message #205254 is a reply to message #205250] |
Fri, 19 April 2013 13:25 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I have used glyptal to coat Ragusa aluminum pans for the express purpose of
sealing porosities several times, including my own. I apply two heavy coats
by brush, with 24 hours between coats. Finish with baking in 175 degree
oven for 4 hours. I have not had any leakage after this treatment. My
Ragusa pan came with button head Allen fasteners with soft fiber washers
for sealing around the bolts. They work well.
Jim Hupy
Salem, Or
78 Gmc Royale 403
On Apr 19, 2013 10:54 AM, "John Heslinga" <rbeeper@hotmail.com> wrote:
>
>
> Thanks Mike!!!
>
> Hopefully Manny will pipe in here somewhere. He must have a pile of Scrap
> cases outside his shop waiting to go to recycling.
>
> When I was in Amana in the fall I noticed that Jim K. had 3 or 4 Rockwell
> Pans (old) that he had returned to him to bring back to California. I don't
> know what the problems of those were, but it certainly piqued my curiosity
> when the oil pan leakage subject was broached. I'm intending to go down
> the west coast for a car tour in the next couple of weeks and was wondering
> if I should also remove and bring my pan and go as far as San Francisco.
> Shipping and export / import charges of stuff to and from Edmonton adds so
> much to the cost of anything that “Just Fixing it” may be a better option.
> I'm willing to measure, flatten, and machine what I can but that will have
> to wait.
>
> If the problem is porosity I could coat the inside of the pan with Gyptol
> type paint to seal it from the inside. I’ve used Gyptol on Cast block
> porosity successfully in Non pressure areas and non sumps, but I am not
> sure how well it works with a sump of Aluminium and transmission fluid. I
> also do not really like the idea of paint and things that can flake inside
> an engine or transmission.. However many racers swear by it!!! But they
> do not use it in the sumps either.
>
> I like the Pan! I think it is a good idea, and it looks Cool. But I know
> others are having a bit of problem with this pan and the Ragusa as well,
> and this is why I'm asking for help. The returned pans at Amana, my
> problem, the ones shared by J.P., R.F., and Carl are an indicator to me
> that there are some issues here that need resolution. If these cast type
> pans are subject to these leakage problems, Maybe we can create a number of
> solutions for all of us to refer to as we solve our particular problems .
> I've worked with Ford service a number of times before to resolve such
> maintenance issues and the resulting solutions are always shared through
> the bulletin system. Maybe these manufactures could put out a technical
> bulletin with these solutions as well.
>
> With all or your input, I will solve my issue, but I would like to share
> that with everyone!!
>
> My Thanks
> and
> Best regards
> --
> John and Cathie Heslinga
> 1974 Canyonlands 260
> TC4W "Too Cool For Words"
> Retirement Projects Galore
> Edmonton, Alberta
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Transmission Oil Pan Leakage Problem 2 [message #205279 is a reply to message #205254] |
Fri, 19 April 2013 17:59 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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I looked at my Rockwell pan this afternoon. The rear edge of the Rockwell abuts the rear transmission case just enough to not allow it to seal tightly. It rests with enough clearance so that you can actually see the seepage. Seepage is very light, but is there.
I will remove the pan and remove enough of the edge to allow it to seal tightly.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Transmission Oil Pan Leakage Problem 2 [message #205425 is a reply to message #204968] |
Sun, 21 April 2013 14:07 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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Emery:
Thanks a million!! That's exactly the answer I was looking for!!!
There are actually more bolts on the outside of the tranny than I expected. With all of the rest of the bolts are blind, meaning that bolt thread seepage should not be the problem unless something is cracked. It also confirms for me that the pan will have to be removed and the other issues will need to be diagnosed. It also means that I will need to plan on some more time as some metal repair will be required. Just sealing the bolt threads will likely be ineffective. The issues are not critical right now, as I get other things ready for the new RVing season coming up.
I'll let everyone know the result. Currently I've upgraded the fiber washers with nylon washers under the heads of the bolts and that has sealed everything off pretty well.
Best regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
[Updated on: Sun, 21 April 2013 14:09] Report message to a moderator |
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