Transmission Dilemma...

[davidbeaver1]

I have a dilemma that I hope some can help me with. I have a 2005 Tahoe 4x4 LT with 159K on the clock. A couple of weeks ago, I ran into the dreaded transfer case "pump rub" and had the back half of the case replaced with the stronger case. I got the truck back and everything seemed to be fine. I then took a trip where speeds got up to around 80 mph, standard interstate speeds. When I stopped, smoke surrounded the truck. When I looked underneath, the transmission was leaking on the cross pipe and it was leaking out of shifter seal.

So I took it to my trusted mechanic and he replaced the shifter seal and the vent hose on the transmission but when testing any speed above 75 mph, the transmission now builds enough pressure that it is blowing the seal back out and starts leaking again. I think it is odd that all of this started after having the transfer case repaired and I had no issues with it before the transfer case repair. I drive many highway miles at 75-80 mph.

Anyone know what would have changed that would be causing the transmission to build up enough pressure to blow out seals? It is the original transmission. Thanks for any insight you can provide.
Very Frustrating....

 

[B-train]

Has the level of the trans fluid risen since the repair? Check the level in the transfer case too while you're at it. If they damaged the seal between the transfer case and transmission, it can pump fluid into it. Also, check the vent line, even though it was fixed or replaced. Just make sure it flows easily.

 

[davidbeaver1]

My mechanic stated that the levels were in spec and that neither were high or low. He ran a scanner and said the temps stayed in range after he ran the truck up and down the road. He had no issues with leaks as long as he stayed under 60mph. As soon as he got above 60, it started pushing trans fluid out of the seals and onto the crossover exhaust pipe causing smoke. He replaced the vent tube on the transmission and made sure it was free as well. Baffling....

 

[rockola1971]

Bad pressure control solenoid or sticking associated valve which is usually caused by bore wear or dirty fluid.

 

[davidbeaver1]

Thank you Rockola1971. Is that an easy fix or something that is indication of a rebuild?

 

[rockola1971]

Thank you Rockola1971. Is that an easy fix or something that is indication of a rebuild?

If valve body needs sleeved or honed then it will need to be dropped. Not a job for someone to learn on unless with a competent builder.

 

[davidbeaver1]

I have it scheduled to be rebuilt the week after Christmas. The truck has 160K on the original fluid. I spoke to my mechanic when I first got it and he said that if I changed transmission fluid that old, I would be rebuilding it sooner than later. He said just ride it out until it wouldn't go anymore so thats what I did. I don't really want to keep messing around with it since its my daily driver so a rebuild is what is going to happen. That way I can just move on. Thanks for helping make that decision.

 

[OR VietVet]

I have it scheduled to be rebuilt the week after Christmas. The truck has 160K on the original fluid. I spoke to my mechanic when I first got it and he said that if I changed transmission fluid that old, I would be rebuilding it sooner than later. He said just ride it out until it wouldn't go anymore so thats what I did. I don't really want to keep messing around with it since its my daily driver so a rebuild is what is going to happen. That way I can just move on. Thanks for helping make that decision.

IMO, I would make sure to share what @rockola1971 has said here, to that mechanic, if he is rebuilding the existing unit. If swapping in a rebuilt, is a moot point but fun to talk about with him, anyway.

 

[davidbeaver1]

Will do. Thanks!

 

[YukonRog]

One thing I learned when replacing the transmission in my 05 Yukon, make sure you don't get a "stock" rebuild. The OE parts in the stock 4L60E are really inferior. Just like the TC Pump Rub issue. The upgraded Sun Shell as well as the Regulator Valve, Aluminum Accumulator Pistons and a better extra plate clutch pack to mention a few. Lastly, look into maybe a better/bigger cooler too.