Tranny finally quit today! Please help.

[Squeaky_Wheel]

To give you a little background on my tranny situation/problem please read the following.

Symptoms:
When I cold start the truck and shift into drive it feels as though the torque converter is slipping and it takes a lot of go pedal to make the truck move. If I wait for the truck to warm up it seems to move a little easier. After I get the truck moving down the road in drive it doesn’t want to shift out of 2nd without a little coaxing of the throttle. It seems as though the warmer the tranny fluid the easier and firmer the tranny will shift. When pulling from a stop it will not automatically shift into first unless I mash the pedal to the floor (which I don’t like to do).

Fixes and adjustments:
About 2 months ago I changed the tranny filter and completely flushed the tranny fluid with Type FA fluid (Couldn’t get my hands on Type F). Result: no change in shifting problems.
About 3 weeks ago I replaced the VDV with one from a donor motor and adjusted it per the FSM. Result: no change in shifting problems.
Last night I checked the vacuum on the VDV and it checked out (8" of vacuum (Hg) at the end of the test). I also disconnected the main vacuum hose from the vacuum pump and check to see if it was working intermittently but it seemed to be working fine. I couldn't find any vacuum leaks on any hoses or fittings under the hood.

What happened today:
I drove about 100 miles towing an empty 10k car trailer. I loaded the truck with about 300 lbs of scrap metal. The trailer was loaded with a 1950 F2 and about 200 lbs of scrap metal (total weight of trailer 6300 lbs). I traveled about 20 miles at approx. 55 mph but then got into stop and go traffic for 2 miles on a 3- 4% grade. Just as I was cresting the hill at about 30 mph, 2nd gear, and 8 psi boost I lost all power to the wheels and had to coast to the side of the road. I was able to shift into reverse and back up but all of my forward gears did not work except for 1st which acted like a weak reverse. After an embarrassing 84 mile AAA tow I made it home safely. Before I called it a night I started the truck up and shifted into reverse and it shutters a little but works. If I shift from reverse to any forward gear and then back to reverse I can’t move at all.

The tranny is not leaking, the fluid level is good and does not smell burnt. The diaphragm on the passenger side of the tranny is wet with fluid but doesn’t appear to be leaking. It has looked like this for as long as I can remember.

I am at a loss as to what the problem could be or were to begin finding the problem. Any assistance will be greatly appreciated.

Thank you

 

[-=DeanstuD=-]

I am surprised none of the regulars have responded. This post probably just got bumped off the front page too fast, it happens.

I don't know allot about trans, but I have learned allot just reading the web. There are allot of videos too, but mostly GM.

I know with your abilities and shop you could pull it and rebuild it yourself. After seeing some videos even think I could do it.

I don't know what happened to yours, but it sounds like a seal went bad somewhere to me. Remember I know nothing specific and I am just getting a feel from what I have learned about how an auto trans works. I think the "improves with temperature slip" is a weak pump or seals. I would say pull the pan and look for chunks. With your fluid still good and clean, it doesn't sound like something burned up, but maybe got stuck or snapped off.

It "lost it" while in gear not during a shift, it was holding and let go, so to me, it had pressure it needed and then lost it. Lost it by an already weak seal or pump finally letting go?

I could (and probably am) be way off base and I really have no experience. I always thought auto trans were complicated, but now I see it is a very simple theory of fluid pressure being diverted to move pistons that hold bands and press clutches.

I see three basic reasons for the trans to stop working

1. foreign matter. A chunk of "something" makes a blockage that doesn't allow fluid to flow somewhere or physically stops the movement of a valve/piston.

2. low pressure. A seal wears and no longer holds pressure where it belongs, leaking and therefore not building required pressure to work a piston/valve.

3. Physical damage to components. clutches burn up and loose there material so they go into a constant slip. A piston or valve breaks


So, my guess is #2 since it was actively in gear and holding when it let go, and the fluid is clean, level and unburned. I would apply this logic to three separate sections of the trans. Torque converter, pump, and then the rest of the transmission



Another disclaimer about my lack of knowing anything. Just opinion. Please, someone DO tell me if I am wrong about something, otherwise I will go on thinking i 'get it'

 

[towcat]

I'm going to bet the forward planetaries are blown.

 

[-=DeanstuD=-]

If you remove a cooler line and run the engine, you can tell if the pump is working at all...

:EDIT:

Forget that. it is obviously working, it goes in reverse.

 

[FORDF250HDXLT]

is this the stock/original C6 in the truck.how many miles on the trans?
probably worn out clutch packs (she warned you in advance,but you didn't listen. )

 

[trackspeeder]

I'm going to bet the forward planetaries are blown.

Could be. Or the one way clutch fried.

Time for a rebuild either way.

 

[DragRag]

I have a 4x4 C6 with 20k miles on it, works like new. The catch, I am in northern Cali.

 

[Squeaky_Wheel]

Thank you all for the responses.

I figured it was only a matter of time before something like this was going to happen considering when I changed the filter the tranny pan was full of metal grime. I am only assuming that this is the original transmission and the truck has at least 230k miles on it. I could rebuild it but I am considering purchasing a remanufactured one and putting it in myself due ro simplicity. I am still researching the options and cost associated with rebuilding it myself. Since I am not that familiar with how auto trannies work, was there anything I could have done to prevent this assuming that the tranny was giving me problems from the start of ownership?

 

[icanfixall]

A good rebuilt C6 with some upgrades will cost around $650.00... Not bad at all either. I have around $4800.00 in my built triple disc converter BTS E4OD and another $3000.00 behind that in the Gear Vendors OD.... I'm not rich... I just have the best of both worlds in the trans and overdrive....

 

[david85]

I don't think there is much you could have done. Once you find metal in the pan and its slipping like that, the pin has been pulled from the grenade - it was only a matter of time. Mind you, towing with a transmission in that condition was probably not the best idea.

If you had pulled the transmission when you still had all the gears working I would be tempted to suggest rebuilding it yourself. However since it blew in a catastrophic failure like it did, I would just get a rebuilt one and unload yours as a core to be done with it.

A basic rebuild kit doesn't cost much for a C6, but there is no way you will get away with only new clutches and seals after a situation like this. Well, maybe.....but very unlikely.

 

[-=DeanstuD=-]

...when I changed the filter the tranny pan was full of metal grime...

You didn't mention that before...

 

[-=DeanstuD=-]

Last I heard, you were converting to 5 spd. How goes it?

 

[Squeaky_Wheel]

Last I heard, you were converting to 5 spd. How goes it?

I am terrible at documenting the work that I do on my truck. With that said, the 5 speed swap was a success (with much help from my wife). The whole swap took about 5 days but we ran into some snags along the way. The first was the banks up pipe that I needed to build. The one that I had was for the C6 and did not clear the ZF5 bellhousing. The second was the 2 inch body lift i needed to gain clearance for the new up pipe. The most exciting thing during the swap was the discovery of the LUK flywheel, Pressure Plate, and Clutch that came with the ZF that I bought at the local yard. I now have a smooth operating ZF5 with no roll over noise.

And to all who read this post and are thinking of doing a ZF5 swap, if you have questions feel free to ask.