Transmission fluid leaking from vent
Thread Starter
Racer
Joined: Jun 2001
Posts: 270
Likes: 58
From: Owego NY
Transmission fluid leaking from vent
During a driving class at Watkins Glen I had a problem with transmission fluid leaking out the vent tube on top of the 700r4 transmission in my 1989 Corvette. I lowered the fluid level till it was at the bottom of the full mark, but it still leaked oil out the vent. It has never done this before in normal driving, or during autocross events. It seems to leak more during hard left hand turns. Is this a common problem during road racing with an automatic (please don't tell me to get a 6 speed, I am running what we have)? I did a search of the forum, but did not find anything about this problem. Is there something wrong with my transmission? It shifts, and feels fine.
I am considering extending the vent tube up high on the firewall like in a 4 wheel drive vehicle to keep the oil from being pushed out the vent.
Any thoughts on this idea?
Thanks for any feedback.
Richard
I am considering extending the vent tube up high on the firewall like in a 4 wheel drive vehicle to keep the oil from being pushed out the vent.
Any thoughts on this idea?
Thanks for any feedback.
Richard
Last edited by RichardL; Aug 25, 2006 at 10:27 PM.
Racer
Joined: Jan 2005
Posts: 418
Likes: 45
From: Houston Texas
Had the same problem with my '90 4x4 pickup with same trans. Because it was a 4x4 (I believe), the vent (not fill) tube came up and ended at the top of the bell housing, just behind the distributor where you could not see it. It was burping fluid, running down and appearing like a front seal leak.
Several mechanics, some truck specialists, all in So. California, gave me a dozen different reasons.
I ended up putting a small fuel (riding lawn mower) filter into the end of the tube. That caught the fluid that was burping, and allowed it to drain back into the case, while still breathing as a vent. Seemed to work OK for about 12 years till the daughter rolled the truck. Funeral was last month. Daughter is still walking.
Several mechanics, some truck specialists, all in So. California, gave me a dozen different reasons.
I ended up putting a small fuel (riding lawn mower) filter into the end of the tube. That caught the fluid that was burping, and allowed it to drain back into the case, while still breathing as a vent. Seemed to work OK for about 12 years till the daughter rolled the truck. Funeral was last month. Daughter is still walking.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
I had an issue on a fast Solo I track last year but attributed it
to a weeping dipstick tube seal. Made the repair but have had little
track time this year so I can't say that the problem no longer occurs
at the track. Thanks for the tip - I'll watch the vent.
It would be interesting to visit a shop for a look at the internal
routing to the vent. Can 'G's cause spillage or is something
forcing fluid out? Do you monitor temperatures?
A fix like DMGroh's fuel filter tip beats my thought about fabbing
a small catch-can from a medicine bottle because the filter already
has hose nipples. Get one big enough to have sufficient capacity
to hold the expected amount of fluid and still be able to 'breath'
freely. Position it so it drains back.
You might want to start a thread in AutoX & RR that links to
this one and invite folks to contribute here.
.
to a weeping dipstick tube seal. Made the repair but have had little
track time this year so I can't say that the problem no longer occurs
at the track. Thanks for the tip - I'll watch the vent.
It would be interesting to visit a shop for a look at the internal
routing to the vent. Can 'G's cause spillage or is something
forcing fluid out? Do you monitor temperatures?
A fix like DMGroh's fuel filter tip beats my thought about fabbing
a small catch-can from a medicine bottle because the filter already
has hose nipples. Get one big enough to have sufficient capacity
to hold the expected amount of fluid and still be able to 'breath'
freely. Position it so it drains back.
You might want to start a thread in AutoX & RR that links to
this one and invite folks to contribute here.
.
Thread Starter
Racer
Joined: Jun 2001
Posts: 270
Likes: 58
From: Owego NY
Originally Posted by Slalom4me
I had an issue on a fast Solo I track last year but attributed it
to a weeping dipstick tube seal. Made the repair but have had little
track time this year so I can't say that the problem no longer occurs
at the track. Thanks for the tip - I'll watch the vent.
It would be interesting to visit a shop for a look at the internal
routing to the vent. Can 'G's cause spillage or is something
forcing fluid out? Do you monitor temperatures?
A fix like DMGroh's fuel filter tip beats my thought about fabbing
a small catch-can from a medicine bottle because the filter already
has hose nipples. Get one big enough to have sufficient capacity
to hold the expected amount of fluid and still be able to 'breath'
freely. Position it so it drains back.
You might want to start a thread in AutoX & RR that links to
this one and invite folks to contribute here.
.
to a weeping dipstick tube seal. Made the repair but have had little
track time this year so I can't say that the problem no longer occurs
at the track. Thanks for the tip - I'll watch the vent.
It would be interesting to visit a shop for a look at the internal
routing to the vent. Can 'G's cause spillage or is something
forcing fluid out? Do you monitor temperatures?
A fix like DMGroh's fuel filter tip beats my thought about fabbing
a small catch-can from a medicine bottle because the filter already
has hose nipples. Get one big enough to have sufficient capacity
to hold the expected amount of fluid and still be able to 'breath'
freely. Position it so it drains back.
You might want to start a thread in AutoX & RR that links to
this one and invite folks to contribute here.
.
No I don't have a temp. guage yet. Plan to install one this winter. I have a transmission cooler, but I don't know how hot the fluid gets with it on.
Thanks
Richard
Racer
Joined: Jan 2005
Posts: 418
Likes: 45
From: Houston Texas
That's an example of all the different ideas I was hearing. I did tow a 3000# boat over those Calif Mountains in the 100+ heat, I had an external trans cooler in series with the radiator cooler, and I watched the temps. Filter and fluid was changed at least annually.
I don't think my temps got excessive, because several years later we did a trans rebuild and the clutch packs were appropriate for the mileage, but not toasted.
If you do the fuel filter thing, make sure it's wire-tied vertical so it drains, and the flow arrow points to the trans (may be meaningless, but I wanted the filter cartridge to do it's thing if the vent ingested any dust). I used a clear one so I could see how much it was burping...less than an ounce...but that's all it took the first time to make me start worrying I needed a new tranny.
Good Luck
I don't think my temps got excessive, because several years later we did a trans rebuild and the clutch packs were appropriate for the mileage, but not toasted.
If you do the fuel filter thing, make sure it's wire-tied vertical so it drains, and the flow arrow points to the trans (may be meaningless, but I wanted the filter cartridge to do it's thing if the vent ingested any dust). I used a clear one so I could see how much it was burping...less than an ounce...but that's all it took the first time to make me start worrying I needed a new tranny.
Good Luck
Racer
Joined: Oct 2005
Posts: 427
Likes: 2
From: joplin mo
i had a similar experience in my 88 after an ill timed downshift while autocrossing ,burped out quite a bit of fluid but did not lose anymore after the inital loss.it took awhile for all of it to come off outside of the trans .
john
john
