I have a problem on my K1500 92 Suburban.
The transmission fluid goes to the transfer case !
So I have a leak on the output transfer case seal. I've replaced it, but
nothing changes. When I
open the filler plug of the transfer case, 3 or 4 liters of transmission
fluid goes out ! And then, when I drive about 200 miles, I loose the same
quantity from the 4L60.... And I can find the lost fluid again in the
transfer case....What could be the problem as I can't imagine the
transmission fluid going from a gearbox to another one! What could be the
way used by the fluid?
What should I replace to keep the transmission fluid at its right place?
Moreover, the transmission is a new one from TCI (less than 20 k miles)
Any help will be great!
Thanks in advance for your help!!!!
My 89 did a similar thing. Except it would pump the fluid out of the
transfer case and into the transmission. I found this out after I started
searching for a high pitched squeal coming from the drive train and found
the transfer case about 1 qt low. Never had a leak under the truck so I
checked the transmission and, you guessed it, over full.
In any case, I had the replace the seal between the transmission and the
transfer case. It was kind of a big job, but the shop manual gave fair
instructions. The seal is a double seal (dual cup seal) to hold pressure
from both directions. The problem was the engineers did not provide a drain
hole between the seal to indicate a leak.
This changed sometime before 97. There now is a drain hole in the adaptor
that connects the transmission to the transfer case.
There is? I've never seen one on the GM products. Jeep had
that drain hole, which was a much better system...but I'm still
fixing GM products that put the trans fluid into the t/case without
showing any signs of leakage.
Man, this really ticks me off, but you are right. I must have been working
on a neighbors truck because I did see a drain hole ... somewhere!
In any case, after reading this, I was forced to crawl under my truck to
look and, you guessed it, no drain hole. Then I pulled my shop manual, and
there is only the single double seal shown.
My truck is a 97 K1500, 350, Auto, with a NV243(electric shift).
So, as I mentioned in my other note, my 89 had this seal leak at about 35K
miles. My 97 has 107K on it and I have not had a problem. When the seal
let go on my 89, it almost took out the transfer case because the fluid
transferred out of the transfer case and into the transmission. If the
opposite happens, and you overfill the transfer case, what fails? Do you
loose fluid out the vent?
Yeah...other makes do this. Jeep used a seal at the rear of the
transmission, and one at the front of the t/case. When fluid leaked
from one or the other, it didn't transfer to the other part, it just
leaked into the adapter section, and there was a drain hole in the
adapter section. GM uses a gasket to seal the t/case to the rear
of the transmission, and the one seal on the input shaft of the
t/case to keep fluid in/out on the t/case. Rarely does the t/case
fluid go into the trans, usually always the other way around in
Most of the time....I just notice that trans fluid comes pouring out
of the t/case fill plug when doing regular maintenance inspections.
This automatically tells you what has happened. Usually, the
t/case doesn't seem to spit the oil out anywhere. There is probably
only a certain amount of fluid that will transfer into the t/case due
to the level of fluid in the trans.
But it can come out somewhere... When that seal let go on my 700R4 the
tranny fluid would spit out from <somewhere> while decelerating off of the
expressway, spray over the exhaust, and cause one HELL of a smokeshow.
Funny, several mechanics didn't believe me that the tranny fluid kept
dropping and insisted it was coolant going through the engine... Idiots...
As Gary mentions, you probably had oil coming out the vent. There is
no seal on the GM transmissions at the rear if it's a 4x4. It's the front
seal on the t/case that fails. In that case, the fluid goes nowhere, but
into the t/case. Your situation is totally different then what is being
discussed in this thread.
How do you figure? The seal on the front of my t-case went out allowing ATF
to fill the t-case. My ATF just found a way out when put under pressure (in
a spectacular fashion I might add) which is rather unusual. I don't see how
that is terribly different than Phil's situation...
Sorry, just going by what your post said. You said "when that
seal let go on my 700R4". There is no seal on the transmission
that allows the fluid to go into the t/case, but as your subsequent
post mentions, you really meant the front seal on the t/case. I
haven't seen a transfer case blow oil out of its vent...but I've seen
lots of transmissions blow oil out their vents. So my assumption
was that you were talking about your transmission blowing oil
No need for apologies Ian, it's obvious that slackjaw is either full of it
or just making up stories. How could a transfer case build up enough
pressure to blow enough fluid out to create the kind of smoke he's talking
about? I've never seen it and don't believe it for a second.
You tell me Gary, how does a transfer case get enough pressure in it to
"spray over the exhaust, and cause one HELL of a smokeshow"? I'm not saying
they can't leak but I've never seen one leak that bad unless it had a hole
in the case. As you well know however transmissions are notorious for
blowing ATF on the exhaust and smoking like hell.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.