Running transfer case overfilled

[turtlevette]

02 suburban transmission started slipping on the highway. The oil level wasn't even touching the dipstick. Common problem is the seal between the transmission and transfer case is shot allowing all the fluid to go into the tc. But if you keep adding to the transmission you'll reach some equilibrium where the tc is overfull and can't accept any more fluid.

Have any of you been successful in running this way long term? Its a bunch of money to get this fixed. I'm thinking downside is blowing out the front driveshaft seal on the tc and or blowing oil out the vent making a mess but can't envision any mechanical damage.

 

[Chris142]

My boss had a blazer that did this. it got so full that it sucked atf in to the vacuum controller thingy on the transfercase. From there it got sucked into every vacuum hose in the dash. Swelling them up rendering the dash useless and finally overflowing the ash tray with atf. My fix was to remove the transfercase fill plug,let the atf run out and put the plug back in @ every oil change.

 

[tcp71]

run a hose from the TC fill plug to the transmission dipstick tube? Automatic leveling system.

 

[turtlevette]

I'm thinking my 02 has electronic controls, but I have no qualms disconnecting and plugging vacuum lines. I never put it in 4wd anyway.

 

[maxdustington]

Originally Posted By: Chris142
My boss had a blazer that did this. it got so full that it sucked atf in to the vacuum controller thingy on the transfercase. From there it got sucked into every vacuum hose in the dash. Swelling them up rendering the dash useless and finally overflowing the ash tray with atf. My fix was to remove the transfercase fill plug,let the atf run out and put the plug back in @ every oil change.

 

[Chris142]

Originally Posted By: turtlevette
I'm thinking my 02 has electronic controls, but I have no qualms disconnecting and plugging vacuum lines. I never put it in 4wd anyway.

The vacuum may keep it in 2wd. If you disconnect the vacuum hoses it may be stuck in 4x4.

 

[turtlevette]

Originally Posted By: Chris142
Originally Posted By: turtlevette
I'm thinking my 02 has electronic controls, but I have no qualms disconnecting and plugging vacuum lines. I never put it in 4wd anyway.

The vacuum may keep it in 2wd. If you disconnect the vacuum hoses it may be stuck in 4x4.


That would be a really bad design. Hose falls off and puts it in 4wd and wrecks the vehicle.

This one is all electric.

 

[andyd]

The Rat leaks dex/merc somewhere down there. Rust prevention. The connection is open not supposed to be sharing. the ouput bearing has a seal, and the input on the TC as well. The T case bolts to trans without goop or a gasket, IIRC it has drain and fills. AMC Jeeps had the same setup.

 

[philipp10]

Originally Posted By: turtlevette
I'm thinking my 02 has electronic controls, but I have no qualms disconnecting and plugging vacuum lines. I never put it in 4wd anyway.



"I never put it in 4wd anyway."....that says it all....lol

 

[dlundblad]

In the blazer world, I've just read it causes it to be overfilled and leaks out of the vent. With mine, the vent runs to the transmission dip stick tube so you may want to at least check where that's at before trying it and making a mess.

 

[dlundblad]

Originally Posted By: Chris142
My boss had a blazer that did this. it got so full that it sucked atf in to the vacuum controller thingy on the transfercase. From there it got sucked into every vacuum hose in the dash. Swelling them up rendering the dash useless and finally overflowing the ash tray with atf. My fix was to remove the transfercase fill plug,let the atf run out and put the plug back in @ every oil change.


A faulty t case switch may have been the issue as well. GM has an updated part. Many people online make the mistake of buying the $20 Dorman part too which doesn't help. I want to say RA sells it as a reverse light switch? That's not what it is at all.. Lol.

The one in my truck was bad and was actually sucking ATF out and into the manifold, HVAC actuators, 4x4 actuator etc. The t case was always low whenever I checked it. I only had air out of the defrost and feet, but somehow the 4x4 system still worked. The transmission level was always correct.

 

[blair]

Why does anyone buy GM?