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?Waldo? Samba Member
Joined: February 22, 2006 Posts: 9752 Location: Where?
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Posted: Tue Feb 24, 2009 1:16 pm Post subject: A Little Known Cause of Recurring Tranny Oil Leaks |
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For those that don't know, on the WBX tranny case there is an atmospheric bleed that is located at the front top of the case. It is next to the top driver's side bolt in the front-most seam of the tranny. It is a small hole (1/8"-3/16"?) with a small screen to keep dirt out of the transmission. It exists to relieve the pressure that will build up in the transmission when the tranny lube expands as it heats up. If it ever becomes blocked (not an uncommon occurrence considering it's exposure to both dust and tranny fluid) then the tranny case will become pressurized and will leak from anywhere it can (drive flange seals, shifter seal, input shaft seal). The cure is fairly simple. Dig the bulk of the crud out with a small screwdriver taking care not to mess up the screen and then hose it down with some WD-40 to finish the job. The hardest part about that is that the location of the hole. Mirror and light come in handy.
Before attempting to fix any transmission oil leaks MAKE SURE THE ATMOSPHERIC BLEED IS NOT PLUGGED.
Andrew |
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ThorAlex Samba Member
Joined: August 31, 2006 Posts: 620 Location: Norway
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Posted: Tue Feb 24, 2009 2:52 pm Post subject: |
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just what i needed, when i needed it! I'm in the prosess of removing the tranny to put in a better clutch and descovered my tranny seems to be leaking from everywere. I hope it's just that.
Oh btw: Any idea were it sits on a syncro box? |
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Famous 01 Samba Member
Joined: May 19, 2007 Posts: 81 Location: Concord, NC
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Posted: Tue Feb 24, 2009 4:22 pm Post subject: |
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Andrew you are the man! I've seen this hole and wondered why.
Tell me this: I had a tranny that was covered in oil crude all over the top and front of the tranny. I thought maybe tranny fluid was coming out of this vent hole. You know, the ill-informed owner might top off fluid until it runs out the of the fill hole but if you put in the measured amount, it comes to someting well below the fill hole. Do you think fluid can come out of that vent hole if it's overfilled?
-Kent
88 Van, 2.2L Suby
90 Van, 2.5L Suby |
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Robw_z Samba Member
Joined: April 28, 2007 Posts: 983
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Posted: Wed Feb 25, 2009 2:08 am Post subject: |
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I found out about that hole the hard way when I left a trans sitting on it's bottom leaning on the side of the garage. I hope the screen is internal cuz I don't see any screen.
-Rob |
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pushkick Samba Member
Joined: August 09, 2007 Posts: 1366
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Posted: Wed Feb 25, 2009 8:13 am Post subject: breather hole in transmission |
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any pics of this hole or breather? or a reference to bently? cant seem to find it?
thnks |
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?Waldo? Samba Member
Joined: February 22, 2006 Posts: 9752 Location: Where?
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Posted: Wed Feb 25, 2009 9:03 am Post subject: |
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I don't currently have any pics as I don't have a tranny out of a van at the moment. Taking a picture of the hole with the transmission in the van would require contortion and juggling skills. It's only really visible using a mirror and light and a camera to the mix and it becomes un-fun. J Charlton is sending me a couple pics of a tranny he has on the bench and I will indicate on those and post it up. It is not indicated anywhere in the Bentley that I'm aware of (thus the "little known" comment).
I have always filled the transmission on level ground until it flows out of the fill hole. It's my experience that all VW manual transmissions (at least to 2000) are filled correctly that way except for the mid-80's golf/jetta where the fill hole was inadvertently cast in the wrong location. I find that there is always residual oil left in the case unless it is tipped various directions and so filling with the capacity listed in the Bentley will result is an over-filled transmission. Additionally, if the fill hole level is not used then how would one top off the transmission fluid? If someone can indicate information to the contrary I'd like to see it.
I'm sure that if overfilled that fluid could definitely be forced out the breather, but to over-fill, one would have to either have the van un-level during filling or fill through a different hole than the fill plug (reverse light?).
I do not know where it is located on a syncro, but will have a 5-speed (094) on the ground soon and will take pics then. It is very likely in the same location on a syncro box.
Andrew |
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ThorAlex Samba Member
Joined: August 31, 2006 Posts: 620 Location: Norway
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Posted: Wed Feb 25, 2009 9:07 am Post subject: |
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I'm removing the syncro tranny this week, i'l post a pic when it's out and cleaned up a little. |
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pushkick Samba Member
Joined: August 09, 2007 Posts: 1366
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Posted: Wed Feb 25, 2009 9:40 am Post subject: |
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i have a 1990 vw vanagn camper automatic and it seems to have a breather on top of the trany. is this what you are talking about? |
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vanaguy Samba Member
Joined: November 20, 2006 Posts: 225 Location: Sumner, WA
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Posted: Wed Feb 25, 2009 10:16 am Post subject: |
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The syncro has a banjo bolt that attaches a plastic vent line to the tranny. This vent line is routed along the left upper side of the tranny towards the rear where it curves into the front of the engine bay and tucks above the gas tank, along with vent lines from the front diff and bell housing. |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9895 Location: Orbiting San Diego
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Posted: Wed Feb 25, 2009 10:35 am Post subject: |
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All of the Vanagon manual trannys have it in the same spot on the top of the tranny. Syncros have a larger and threaded hole there since Syncros have a plastic tube from it to a high spot to allow crossing of deep water without water entering the tranny through the vent hole.
Mark
ThorAlex wrote: |
just what i needed, when i needed it! I'm in the prosess of removing the tranny to put in a better clutch and descovered my tranny seems to be leaking from everywere. I hope it's just that.
Oh btw: Any idea were it sits on a syncro box? |
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MsTaboo Samba Member
Joined: June 02, 2006 Posts: 4065 Location: East Kootenay, British Columbia
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Posted: Wed Feb 25, 2009 1:13 pm Post subject: |
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crazyvwvanman. Thanks for this post!
When I pulled my engine in preparation for doing a Zetec conversion I was surprised by this line on my Syncro. There is no mention I could find in Bentley about it's function.
Any idea about the terminal end of the line? It seems to disappear into the firewall along with other vacuum lines?? Does it merely dead end? Or is it connected to something?
Here is a shot of the hole in front of Syncro tranny case.
_________________ Currently:
'90 Syncro Westy 3 knob w/Zetec
The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
Help the fight against Truth Decay.
Defend democracy, support Ukraine.
Last edited by MsTaboo on Wed Feb 25, 2009 1:51 pm; edited 1 time in total |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9895 Location: Orbiting San Diego
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Posted: Wed Feb 25, 2009 1:27 pm Post subject: |
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That vent tube just ends, usually tucked up above the Syncro fuel tank area. The other 2 vent tubes also end there. One from the clutch area, one from the front diff.
Mark
71MYSTABOO wrote: |
crazyvwvanman. Thanks for this post!
When I pulled my engine in preparation for doing a Zetec conversion I was surprised by this line on my Syncro. There is no mention I could find in Bentley about it's function.
Any idea about the terminal end of the line? It seems to disappear into the firewall along with other vacuum lines?? Dose it merely dead end? Or is it connected to something?
Here is a shot of the hole in front of Syncro tranny case.
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?Waldo? Samba Member
Joined: February 22, 2006 Posts: 9752 Location: Where?
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Posted: Wed Feb 25, 2009 1:46 pm Post subject: |
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The arrow points to it's location on the WBX tranny.
As I mentioned, the plugging of this hole is not uncommon. I have another van here that recently developed a weeping simultaneously at both of the drive flange seals which were replaced about 2 years ago. I just hopped under it and the sound deadening foam was resting against the vent area and a significant amount of crud was blocking the hole. I'm sure that's the issue and thankfully much easier to address than changing both drive flange seals again. I also Know that I cleaned that vent hole 2 years ago when I replaced those seals, so the buildup can happen relatively quickly and if it isn't cleaned, then no amount of seal replacement will prevent the leakage.
Andrew |
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stevey88 Samba Member
Joined: January 16, 2008 Posts: 1317 Location: Fremont, SF Bay Area
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Posted: Wed Feb 25, 2009 2:08 pm Post subject: |
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Quote: |
You know, the ill-informed owner might top off fluid until it runs out the of the fill hole but if you put in the measured amount, it comes to someting well below the fill hole. |
I think the well informed know why VW change the oil level in the gear box from filling to the filler hole to less than the filler hole. _________________ Steve
87 Westfalia full camper 4 speed |
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?Waldo? Samba Member
Joined: February 22, 2006 Posts: 9752 Location: Where?
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Posted: Wed Feb 25, 2009 2:17 pm Post subject: |
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Can you please post a source for a VW spec for tranny fluid level that is less than the bottom of the fill hole?
Andrew |
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stevey88 Samba Member
Joined: January 16, 2008 Posts: 1317 Location: Fremont, SF Bay Area
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Posted: Wed Feb 25, 2009 3:42 pm Post subject: |
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I don't have my bentley or owner's manual close by but I think both said fill the gear box a certain amount below the fill hole. I learned from the experts in this forum VW lower the oil level for the vanagon gear box in order to improve the shifting. Lower the drag on the gear so the syncho ring can speed up or slow down the gears faster I guess. I currently use MT90 and I fill it to the brim. I have own many stick shift cars and every single one specify fill the gear oil to the filler plug. _________________ Steve
87 Westfalia full camper 4 speed |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9895 Location: Orbiting San Diego
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Posted: Wed Feb 25, 2009 4:01 pm Post subject: |
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It says it in the Bentley in the transmission pages notes.
35.32
35.60
I still would not do it as I don't think improving the shifting would be worth the risk.
Mark
Andrew A. Libby wrote: |
Can you please post a source for a VW spec for tranny fluid level that is less than the bottom of the fill hole?
Andrew |
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?Waldo? Samba Member
Joined: February 22, 2006 Posts: 9752 Location: Where?
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Posted: Wed Feb 25, 2009 5:12 pm Post subject: |
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Thanks Mark. I hadn't noticed the note. I haven't ever noticed excessive shifting effort unless there was an issue with the linkage. I think I'll maintain my current method unless anyone has any further reasons not to.
Andrew |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50259
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Posted: Wed Feb 25, 2009 6:26 pm Post subject: |
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When I bought my Syncro it didn't shift worth beans, just about took two hands to get it into gear, so I drained a little fluid out to get it to the specified 1/2" below the plug level. Still didn't shift worth beans. Tried various oils and finally ended up running either a 0W-30 or 5W-30 synthetic motor oil in the gear box. That was about 15 years ago, shifted fine until it recently got parked due to an internal coolant leak in the engine at just shy of 300K miles.
I my opinion the 1/2" below plug level is just VW baloney. |
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?Waldo? Samba Member
Joined: February 22, 2006 Posts: 9752 Location: Where?
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Posted: Thu Feb 26, 2009 2:05 pm Post subject: |
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I happened to pick up a used WBX tranny today and decided to pull the "nose cone" and check out the breather hole. I'm afraid I misspoke previously. Disturbingly enough there is no screen in the breather. I was speaking previously from memory, but the memory must have been from a non-vanagon tranny or an addled memory. Here are a few pics:
As can be seen, a significant amount of crud has made it's way into the transmission through the breather. Although incredibly unlikely, it would be possible for a BB sized rock or other road debris could actually enter the transmission. That's an alarming thought. I may add a small filter like this obviously with a different connection (that is from a diesel pop tester I built):
The filter would both reduce the amount of crud getting into the transmission and simultaneously reduce or eliminate the odds of the breather being clogged. Additionally changing the filter would be extremely easy.
Andrew
Last edited by ?Waldo? on Thu Feb 26, 2009 7:50 pm; edited 1 time in total |
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