Home » Public Forums » GMCnet » [GMCnet] Final Drive cover vent hole?
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| Re: [GMCnet] Final Drive cover vent hole? [message #170011 is a reply to message #170010] |
Thu, 17 May 2012 17:09   |
Rick
Messages: 36
Registered: September 2010
Location: Ft. Worth
Karma: 0
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Member |
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Rob, yes it is a steel cover and there is a vent hole on top.
It's at AAMCO getting work done (more than I care to think about!)
The first time it was in the shop for tranny and F.D. fluid change, the seals were leaking so the mechanic pulled the cover and found the hole filed with RTV. He surmised that the plugged vent caused a pressure build up that blew out the seals. Sounded resonable to me (oops, my ignorance is showing again). He cleaned off the RTV and it's leaked out fluid when ever driven.
The GMC is back in the shop and among other things the transmission was completely rebuilt and the F.D. Is still oozing.
The mechanic has suggested fitting a breather tube the hole to allow it to vent higher.
I've owned my GMC for a month and the mechanic has had it more than me! :(
Sent from my iPad
On May 17, 2012, at 4:49 PM, "Rob Mueller" <robmueller@iinet.net.au> wrote:
> Rick,
>
> Need some clarification:
>
> 1) Is the cover on your final drive steel?
>
> 2) Are you saying that there is a vent hole in the top of your final drive cover and oil comes out whenever you drive it?
>
> If it is two the answer is there should not be any holes in the final drive cover. The final drive cover uses a multi layer gasket
> that has a convoluted path through it at the top to vent the final drive.
>
> Regards,
> Rob M.
>
>
> -----Original Message-----
> From: Rick
>
> On the final drive cover should there be a vent (breather) hole at the top?
> If so, what does it mean when fluid spills out every time it's driven?
>
> Rick D.
>
> _______________________________________________
> GMCnet mailing list
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Rick Does Ft. Worth Tx
1976 Glenbrook "Some Assembly Required"
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| Re: [GMCnet] Final Drive cover vent hole? [message #170014 is a reply to message #170011] |
Thu, 17 May 2012 17:36 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Rick,
Now that's an interesting PO (Previous Owner) mod! I'm sitting here thinking about what ran through the mind of the "mechanic" that
did it!
"Hmm, there's no vent in the cover of this differential, all the other diffs I've seen had holes in them, I better punch a hole in
the top."
You could send in a message to the GMCnet asking if anyone has a spare to sell (I don't) or buy one of these:
http://www.appliedgmc.com/prod.itml/icOid/706
and
http://www.appliedgmc.com/prod.itml/icOid/707
Oh yeah, before you order it you need to count how many bolts hold the cover on to the final drive, the one above is for a standard
GMC OEM final drive with ten (10) bolts.
If your final drive cover has nine (9) bolts it is a planetary final drive and needs one of these covers:
http://www.appliedgmc.com/prod.itml/icOid/926
Unfortunately JimK doesn't sell a gasket for this cover, HOWEVER, you may be able to get one from John Biwersi; I have Cc'd him on
this email. He can be contacted on:
2938 North Mary Street
Maplewood, MN 55109-1671
jbiwersi at mac dot com
six five one - seven seven nine - six four nine eight
The nice feature of both these covers is that they have a drain hole so you can change the oil without having to remove it.
BTW I read Emery's message to you after I posted my original message and he noted good points (OBVIOUSLY!). Ask the mechanic if the
"ooze" has a red tint to it.
Finally if you need a rebuilt trans I would recommend you get it from Manny Trovao, he's Mr. T; for TRANSMISSION! He does a number
of mods that improve the reliability and performance of the trans. I have Cc'd him on this email. He can be contacted at:
11447 Clayton Road
San Jose, CA 95127
mannystrans at gmail dot com
four zero eight - nine three seven - one five eight three
Regards,
Rob M.
-----Original Message-----
From: Rick
Rob, yes it is a steel cover and there is a vent hole on top.
It's at AAMCO getting work done (more than I care to think about!)
The first time it was in the shop for tranny and F.D. fluid change, the seals were leaking so the mechanic pulled the cover and
found the hole filed with RTV. He surmised that the plugged vent caused a pressure build up that blew out the seals. Sounded
resonable to me (oops, my ignorance is showing again). He cleaned off the RTV and it's leaked out fluid when ever driven.
The GMC is back in the shop and among other things the transmission was completely rebuilt and the F.D. Is still oozing.
The mechanic has suggested fitting a breather tube the hole to allow it to vent higher.
I've owned my GMC for a month and the mechanic has had it more than me! :(
_______________________________________________
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Final Drive cover vent hole? [message #170024 is a reply to message #170014] |
Thu, 17 May 2012 18:11 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Rick, the final drive only holds 2 quarts of gear oil.I will reaffirm what
Emery said about looking at the fluid that is dripping out and make very
sure that it is not pink. There is a very special seal that has two lips
back to back. It installs into the final drive pinion shaft area. It is
very hard to find, and many final drives have been fitted with two narrow
seals back to back as a replacement. The purchase area for the seals is
quite narrow, with an annular passage in the middle of it to allow a slight
amount of either ATF or Gear oil to leak out onto the floor. I am talking
drips per month here when I say small amount. When it drips, it appears to
come from between the final drive and the transmission. If an excessive
amount of either ATF or Gear oil leaks there, it is a sure sign that the
double lipped seal has failed and needs to be replaced. In order for that
to happen, the final drive needs to be removed. It is no place for an
unskilled mechanic to learn his trade at your expense. The remote
possibility also exists that the final drive case has been overfilled.
If this is the case, and someone puts the cover on with RTV and no gasket,
I gurantee you that the final drive will leak at the axle flanges, and
perhaps between the cases as well. The steel final drive cover has a vent
hole near the top bolt. It is 1/8" in diameter. There are two gaskets
currently available for the final drive. One looks like two gaskets stapled
together. they are the same basic shape, but the one that goes towards the
final drive contains a maze like passage that terminates under the small
1/8" hole. (NOTE)
there is not a hole in the gasket that matches with the hole in the cover.
When the gasket is fitted and final tightening is complete, take an 1/8"
drill bit between your thumb and finger, and drill a hole through the
gasket. That completes the venting maze to the atmosphere. The reason the
gasket is not pre punched, is there are differences in the metal covers as
to hole placement, so they expect the installer to complete this step. If
this vent hole is plugged with RTV sealant or grease, the final drive will
leak. The second type of gasket I mentioned earlier is a thicker material
with a maze built into it. I think that this one is an official GM part. I
don't know for sure, but I think perhaps this one is no longer in
production. New old stock would be the supply source for it.
I fix these things frequently, and find many overfilled and nearly all
the vent holes plugged. I have encountered final drive cases that have been
drilled on the top of the case, and elbow fittings with hoses attatched
were used for the vents.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Thu, May 17, 2012 at 3:36 PM, Rob Mueller <robmueller@iinet.net.au>wrote:
> Rick,
>
> Now that's an interesting PO (Previous Owner) mod! I'm sitting here
> thinking about what ran through the mind of the "mechanic" that
> did it!
>
> "Hmm, there's no vent in the cover of this differential, all the other
> diffs I've seen had holes in them, I better punch a hole in
> the top."
>
> You could send in a message to the GMCnet asking if anyone has a spare to
> sell (I don't) or buy one of these:
>
> http://www.appliedgmc.com/prod.itml/icOid/706
>
> and
>
> http://www.appliedgmc.com/prod.itml/icOid/707
>
> Oh yeah, before you order it you need to count how many bolts hold the
> cover on to the final drive, the one above is for a standard
> GMC OEM final drive with ten (10) bolts.
>
> If your final drive cover has nine (9) bolts it is a planetary final drive
> and needs one of these covers:
>
> http://www.appliedgmc.com/prod.itml/icOid/926
>
> Unfortunately JimK doesn't sell a gasket for this cover, HOWEVER, you may
> be able to get one from John Biwersi; I have Cc'd him on
> this email. He can be contacted on:
>
> 2938 North Mary Street
> Maplewood, MN 55109-1671
> jbiwersi at mac dot com
> six five one - seven seven nine - six four nine eight
>
> The nice feature of both these covers is that they have a drain hole so
> you can change the oil without having to remove it.
>
> BTW I read Emery's message to you after I posted my original message and
> he noted good points (OBVIOUSLY!). Ask the mechanic if the
> "ooze" has a red tint to it.
>
> Finally if you need a rebuilt trans I would recommend you get it from
> Manny Trovao, he's Mr. T; for TRANSMISSION! He does a number
> of mods that improve the reliability and performance of the trans. I have
> Cc'd him on this email. He can be contacted at:
>
> 11447 Clayton Road
> San Jose, CA 95127
> mannystrans at gmail dot com
> four zero eight - nine three seven - one five eight three
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Rick
>
> Rob, yes it is a steel cover and there is a vent hole on top.
> It's at AAMCO getting work done (more than I care to think about!)
> The first time it was in the shop for tranny and F.D. fluid change, the
> seals were leaking so the mechanic pulled the cover and
> found the hole filed with RTV. He surmised that the plugged vent caused a
> pressure build up that blew out the seals. Sounded
> resonable to me (oops, my ignorance is showing again). He cleaned off the
> RTV and it's leaked out fluid when ever driven.
> The GMC is back in the shop and among other things the transmission was
> completely rebuilt and the F.D. Is still oozing.
> The mechanic has suggested fitting a breather tube the hole to allow it to
> vent higher.
>
> I've owned my GMC for a month and the mechanic has had it more than me! :(
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
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Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Final Drive cover vent hole? [message #170028 is a reply to message #170000] |
Thu, 17 May 2012 18:36 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| Rick wrote on Thu, 17 May 2012 16:40 |
On the final drive cover should there be a vent (breather) hole at the top?
If so, what does it mean when fluid spills out every time it's driven?
Rick D.
|
Rick,
Yes, the FD is supposed to have that hole up there and it is supposed to be covered (not blocked) by a little plate held down by a cover screw.
If fluid comes out of that hole, it means the FD is over filled. It could just be over filled (mechanics love to cram fluid in and then shove the plug in before it can level out). Or as Rob said, maybe the seal to the trans could be leaking and over filling it.
Easy test: (sort of)
Take the fill plug out and let the FD drain to level.
Put the plug back in and drive the coach.
Pull the plug again
- More Fluid? go back to AAMCO - The trans is leaking into the FD
- No Fluid? Read on
Any case, if you used a gasket, that gasket is probably wrong. If the mechanic resealed it with RV, it will be probably be wrong and it weep almost forever.
The vent hole is supposed to be an atmospheric vent only. Just enough to allow for changes in temperature and local pressure to not overload the axle shaft seals. The original vent hole was into the gasketed joint. The gasket was a two layer piece with a long path coined (compressed) into the thicker piece to make the path to the vent. This can be done with a formed-in-place, but it is really difficult.
I used to be the aftermarket of a major gasket supplier. When I resealed my FD, I sought out a special number because I knew that should be off my old tooling. Well, I was wrong. The three different suppliers I looked at were all selling a part with no vent in the gasket.
What did I do (when I was though fuming)?
I laid the gasket on the FD and set the cover on. I spun a drill into the gasket through the vent hole. The I took the thicker piece of gasket over to a hard plate and got a piece of mechanics wire and laid that on the gasket between the hole and somewhere about an inch and an half down and used it to beat a groove (home coining) into the gasket so it would end up between the layers. It has been just fine.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Final Drive cover vent hole? [message #170039 is a reply to message #170014] |
Thu, 17 May 2012 19:58 |
Rick
Messages: 36
Registered: September 2010
Location: Ft. Worth
Karma: 0
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Member |
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I like the idea of ordering the new cover with the drain hole.
According to the PO it has a Jim K (3.73?) final drive installed, will that affect which cover I can put on it?
Rick D.
Sent from my iPad
On May 17, 2012, at 5:36 PM, "Rob Mueller" <robmueller@iinet.net.au> wrote:
> Rick,
>
> Now that's an interesting PO (Previous Owner) mod! I'm sitting here thinking about what ran through the mind of the "mechanic" that
> did it!
>
> "Hmm, there's no vent in the cover of this differential, all the other diffs I've seen had holes in them, I better punch a hole in
> the top."
>
> You could send in a message to the GMCnet asking if anyone has a spare to sell (I don't) or buy one of these:
>
> http://www.appliedgmc.com/prod.itml/icOid/706
>
> and
>
> http://www.appliedgmc.com/prod.itml/icOid/707
>
> Oh yeah, before you order it you need to count how many bolts hold the cover on to the final drive, the one above is for a standard
> GMC OEM final drive with ten (10) bolts.
>
> If your final drive cover has nine (9) bolts it is a planetary final drive and needs one of these covers:
>
> http://www.appliedgmc.com/prod.itml/icOid/926
>
> Unfortunately JimK doesn't sell a gasket for this cover, HOWEVER, you may be able to get one from John Biwersi; I have Cc'd him on
> this email. He can be contacted on:
>
> 2938 North Mary Street
> Maplewood, MN 55109-1671
> jbiwersi at mac dot com
> six five one - seven seven nine - six four nine eight
>
> The nice feature of both these covers is that they have a drain hole so you can change the oil without having to remove it.
>
> BTW I read Emery's message to you after I posted my original message and he noted good points (OBVIOUSLY!). Ask the mechanic if the
> "ooze" has a red tint to it.
>
> Finally if you need a rebuilt trans I would recommend you get it from Manny Trovao, he's Mr. T; for TRANSMISSION! He does a number
> of mods that improve the reliability and performance of the trans. I have Cc'd him on this email. He can be contacted at:
>
> 11447 Clayton Road
> San Jose, CA 95127
> mannystrans at gmail dot com
> four zero eight - nine three seven - one five eight three
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Rick
>
> Rob, yes it is a steel cover and there is a vent hole on top.
> It's at AAMCO getting work done (more than I care to think about!)
> The first time it was in the shop for tranny and F.D. fluid change, the seals were leaking so the mechanic pulled the cover and
> found the hole filed with RTV. He surmised that the plugged vent caused a pressure build up that blew out the seals. Sounded
> resonable to me (oops, my ignorance is showing again). He cleaned off the RTV and it's leaked out fluid when ever driven.
> The GMC is back in the shop and among other things the transmission was completely rebuilt and the F.D. Is still oozing.
> The mechanic has suggested fitting a breather tube the hole to allow it to vent higher.
>
> I've owned my GMC for a month and the mechanic has had it more than me! :(
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Rick Does Ft. Worth Tx
1976 Glenbrook "Some Assembly Required"
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| Re: [GMCnet] Final Drive cover vent hole? [message #170041 is a reply to message #170028] |
Thu, 17 May 2012 20:07 |
|
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
|
|
Matt,
I think I misinterpreted what Rick has noted about a "hole." I pictured a hole in the cover itself. The hole you speak of is in the
mounting flange just to the right left of the top mounting bolt and is covered with a plate.
Reference Parts Book 78Z page 1-2 Key 35 Shield - vent, housing cover.
If one looks at Key 32 - SHIELD KIT, housing cover (SOA) (repl. 409729) you can see the "slot" in the gasket that lines up with the
hole in the flange.
Rick,
Here's a link to the Parts Book; let us know if this is where the oil is coming from?
http://www.bdub.net/manuals/parts/index.html
Regards,
Rob M.
-----Original Message-----
From: Matt Colie
Rick,
Yes, the FD is supposed to have that hole up there and it is supposed to be covered (not blocked) by a little plate held down by a
cover screw.
If fluid comes out of that hole, it means the FD is over filled. It could just be over filled (mechanics love to cram fluid in and
then shove the plug in before it can level out). Or as Rob said, maybe the seal to the trans could be leaking and over filling it.
Easy test: (sort of)
Take the fill plug out and let the FD drain to level.
Put the plug back in and drive the coach.
Pull the plug again
- More Fluid? go back to AAMCO - The trans is leaking into the FD
- No Fluid? Read on
Any case, if you used a gasket, that gasket is probably wrong. If the mechanic resealed it with RV, it will be probably be wrong
and it weep almost forever.
The vent hole is supposed to be an atmospheric vent only. Just enough to allow for changes in temperature and local pressure to not
overload the axle shaft seals. The original vent hole was into the gasketed joint. The gasket was a two layer piece with a long
path coined (compressed) into the thicker piece to make the path to the vent. This can be done with a formed-in-place, but it is
really difficult.
I used to be the aftermarket of a major gasket supplier. When I resealed my FD, I sought out a special number because I knew that
should be off my old tooling. Well, I was wrong. The three different suppliers I looked at were all selling a part with no vent in
the gasket.
What did I do (when I was though fuming)?
I laid the gasket on the FD and set the cover on. I spun a drill into the gasket through the vent hole. The I took the thicker
piece of gasket over to a hard plate and got a piece of mechanics wire and laid that on the gasket between the hole and somewhere
about an inch and an half down and used it to beat a groove (home coining) into the gasket so it would end up between the layers.
It has been just fine.
Matt
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Final Drive cover vent hole? [message #170044 is a reply to message #170041] |
Thu, 17 May 2012 20:35 |
Rick
Messages: 36
Registered: September 2010
Location: Ft. Worth
Karma: 0
|
Member |
|
|
Rob,
Thanks, I will stop over in the morning and verify the 'leak' location.
What is the proper gear lube for the FD?
Rick D.
Sent from my iPad
On May 17, 2012, at 8:07 PM, "Rob Mueller" <robmueller@iinet.net.au> wrote:
> Matt,
>
> I think I misinterpreted what Rick has noted about a "hole." I pictured a hole in the cover itself. The hole you speak of is in the
> mounting flange just to the right left of the top mounting bolt and is covered with a plate.
>
> Reference Parts Book 78Z page 1-2 Key 35 Shield - vent, housing cover.
>
> If one looks at Key 32 - SHIELD KIT, housing cover (SOA) (repl. 409729) you can see the "slot" in the gasket that lines up with the
> hole in the flange.
>
> Rick,
>
> Here's a link to the Parts Book; let us know if this is where the oil is coming from?
>
> http://www.bdub.net/manuals/parts/index.html
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Matt Colie
>
> Rick,
>
> Yes, the FD is supposed to have that hole up there and it is supposed to be covered (not blocked) by a little plate held down by a
> cover screw.
>
> If fluid comes out of that hole, it means the FD is over filled. It could just be over filled (mechanics love to cram fluid in and
> then shove the plug in before it can level out). Or as Rob said, maybe the seal to the trans could be leaking and over filling it.
>
> Easy test: (sort of)
> Take the fill plug out and let the FD drain to level.
> Put the plug back in and drive the coach.
> Pull the plug again
> - More Fluid? go back to AAMCO - The trans is leaking into the FD
> - No Fluid? Read on
>
> Any case, if you used a gasket, that gasket is probably wrong. If the mechanic resealed it with RV, it will be probably be wrong
> and it weep almost forever.
>
> The vent hole is supposed to be an atmospheric vent only. Just enough to allow for changes in temperature and local pressure to not
> overload the axle shaft seals. The original vent hole was into the gasketed joint. The gasket was a two layer piece with a long
> path coined (compressed) into the thicker piece to make the path to the vent. This can be done with a formed-in-place, but it is
> really difficult.
>
> I used to be the aftermarket of a major gasket supplier. When I resealed my FD, I sought out a special number because I knew that
> should be off my old tooling. Well, I was wrong. The three different suppliers I looked at were all selling a part with no vent in
> the gasket.
>
> What did I do (when I was though fuming)?
> I laid the gasket on the FD and set the cover on. I spun a drill into the gasket through the vent hole. The I took the thicker
> piece of gasket over to a hard plate and got a piece of mechanics wire and laid that on the gasket between the hole and somewhere
> about an inch and an half down and used it to beat a groove (home coining) into the gasket so it would end up between the layers.
> It has been just fine.
>
> Matt
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Rick Does Ft. Worth Tx
1976 Glenbrook "Some Assembly Required"
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| Re: [GMCnet] Final Drive cover vent hole? [message #170057 is a reply to message #170044] |
Thu, 17 May 2012 21:57 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
|
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Rick,
Some have commented that the FD gasket is hard to find. I've never had any
trouble ordering them from local suppliers and it's certainly available
from RockAuto.com. Like most drive train parts, '75 Olds Toronado is an
appropriate application. Here's a photo of the gasket, clearly showing
the labyrinthine vent path.
http://www.rockauto.com/catalog/moreinfo.php?pk=3657981
Ken H.
On Thu, May 17, 2012 at 9:35 PM, Rick wrote:
> Rob,
> Thanks, I will stop over in the morning and verify the 'leak' location.
> What is the proper gear lube for the FD?
_______________________________________________
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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] Final Drive cover vent hole? [message #170075 is a reply to message #170064] |
Fri, 18 May 2012 06:55 |
John Wright
Messages: 118
Registered: September 2008
Karma: 0
|
Senior Member |
|
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Rob,
The final drive gaskets for the reg cases 3.07 and any gearing that fit that case is available. The 3.21 gasket is no longer available.
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
On May 18, 2012, at 5:29 AM, Rob Mueller wrote:
> Ken,
>
> I figger'd I give RockAuto a shot to see if they had the 1966-67 Planetary Gear 3.21 to 1 Final Drive cover gasket with nine bolts.
> I checked both years and they show the 10 bolt gasket.
>
> Darn!
>
> Regards,
> Rob M.
>
>
> -----Original Message-----
> From: Of Ken Henderson
>
> Rick,
>
> Some have commented that the FD gasket is hard to find. I've never had any
> trouble ordering them from local suppliers and it's certainly available
> from RockAuto.com. Like most drive train parts, '75 Olds Toronado is an
> appropriate application. Here's a photo of the gasket, clearly showing
> the labyrinthine vent path.
>
> http://www.rockauto.com/catalog/moreinfo.php?pk=3657981
>
> Ken H.
>
>
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| Re: [GMCnet] Final Drive cover vent hole? [message #170109 is a reply to message #170041] |
Fri, 18 May 2012 11:29 |
Rick
Messages: 36
Registered: September 2010
Location: Ft. Worth
Karma: 0
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Member |
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Rob,
I confirmed that the 'hole' in question is the weep hole along the top edge that is shown in the parts drawing.
The gasket used was the 2 piece one. I'm thinking it was over filled the the gear lube.
With luck I will get my MH back today and see for myself that the oozing has stopped!
I think I will follow your Suggestion and order the correct cover from Applied GMC if for no other reason than to get the separate drain and fill holes for more frequent fluid changes.
Cheers,
Rick D.
Sent from my iPad
On May 17, 2012, at 8:07 PM, "Rob Mueller" <robmueller@iinet.net.au> wrote:
> Matt,
>
> I think I misinterpreted what Rick has noted about a "hole." I pictured a hole in the cover itself. The hole you speak of is in the
> mounting flange just to the right left of the top mounting bolt and is covered with a plate.
>
> Reference Parts Book 78Z page 1-2 Key 35 Shield - vent, housing cover.
>
> If one looks at Key 32 - SHIELD KIT, housing cover (SOA) (repl. 409729) you can see the "slot" in the gasket that lines up with the
> hole in the flange.
>
> Rick,
>
> Here's a link to the Parts Book; let us know if this is where the oil is coming from?
>
> http://www.bdub.net/manuals/parts/index.html
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Matt Colie
>
> Rick,
>
> Yes, the FD is supposed to have that hole up there and it is supposed to be covered (not blocked) by a little plate held down by a
> cover screw.
>
> If fluid comes out of that hole, it means the FD is over filled. It could just be over filled (mechanics love to cram fluid in and
> then shove the plug in before it can level out). Or as Rob said, maybe the seal to the trans could be leaking and over filling it.
>
> Easy test: (sort of)
> Take the fill plug out and let the FD drain to level.
> Put the plug back in and drive the coach.
> Pull the plug again
> - More Fluid? go back to AAMCO - The trans is leaking into the FD
> - No Fluid? Read on
>
> Any case, if you used a gasket, that gasket is probably wrong. If the mechanic resealed it with RV, it will be probably be wrong
> and it weep almost forever.
>
> The vent hole is supposed to be an atmospheric vent only. Just enough to allow for changes in temperature and local pressure to not
> overload the axle shaft seals. The original vent hole was into the gasketed joint. The gasket was a two layer piece with a long
> path coined (compressed) into the thicker piece to make the path to the vent. This can be done with a formed-in-place, but it is
> really difficult.
>
> I used to be the aftermarket of a major gasket supplier. When I resealed my FD, I sought out a special number because I knew that
> should be off my old tooling. Well, I was wrong. The three different suppliers I looked at were all selling a part with no vent in
> the gasket.
>
> What did I do (when I was though fuming)?
> I laid the gasket on the FD and set the cover on. I spun a drill into the gasket through the vent hole. The I took the thicker
> piece of gasket over to a hard plate and got a piece of mechanics wire and laid that on the gasket between the hole and somewhere
> about an inch and an half down and used it to beat a groove (home coining) into the gasket so it would end up between the layers.
> It has been just fine.
>
> Matt
>
> _______________________________________________
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Rick Does Ft. Worth Tx
1976 Glenbrook "Some Assembly Required"
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| Re: [GMCnet] Final Drive cover vent hole? [message #170142 is a reply to message #170129] |
Fri, 18 May 2012 20:58 |
Rick
Messages: 36
Registered: September 2010
Location: Ft. Worth
Karma: 0
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Member |
|
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Rob,
Thanks for yours and everyone's input!
Speaking of fluids, what's your take on the Royal Purple products?
Rick D.
Sent from my iPad
On May 18, 2012, at 6:01 PM, "Rob Mueller" <robmueller@iinet.net.au> wrote:
> Rick,
>
> And that's that! ;-)
>
> BTW I just realized that no one answered your question about the correct oil to use. I used:
>
> http://www.mobiloil.com/USA-English/MotorOil/Other_Products/Mobil_1_Fully_Synthetic_Gear_Lube_75W-90LS.aspx
>
> I used their synthetic trans fluid too because Manny recommended it.
>
> http://www.mobiloil.com/USA-English/MotorOil/Other_Products/Mobil_1_Synthetic_ATF.aspx
>
> Regards,
> Rob M.
>
>
> -----Original Message-----
> From: Rick
>
> Rob,
> I confirmed that the 'hole' in question is the weep hole along the top edge that is shown in the parts drawing.
> The gasket used was the 2 piece one. I'm thinking it was over filled the the gear lube.
> With luck I will get my MH back today and see for myself that the oozing has stopped!
> I think I will follow your Suggestion and order the correct cover from Applied GMC if for no other reason than to get the separate
> drain and fill holes for more frequent fluid changes.
>
> Cheers,
> Rick D.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Rick Does Ft. Worth Tx
1976 Glenbrook "Some Assembly Required"
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| Re: [GMCnet] Final Drive cover vent hole? [message #170180 is a reply to message #170146] |
Sat, 19 May 2012 12:24 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
|
Senior Member |
|
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""I have an oil consumption situation on Double Trouble so I decided to switch from Shell Rotella T (15w-40) to Royal Purple Full
Synthetic SAE 40. It was over $7.00 a quart with a trade discount the Napa store manager gave me.
""
Try straight 40 dino oil for oil consumption issues.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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