1987 F350 C-6 transmission question

[JohnFlash]

This is my first post so correct me if I am doing this wrong. My 87 C-6 transmission (135,00 miles) doesn't engage right away when cold. You have to put it in gear and wait until it seemingly gets pumped up to pressure before the truck will move. What could be possibly wrong? After it gets warmed up it seems to work ok. Thanks for the help!

 

[spg]

Start with the basics. Check fluid level, Change fluid and filter. After that more diagnostics such as checking line pressure, vacum modualtor and linkage adjustments. When you change the fluid and filter look at the fluid condition and amount of sediment in the pan. Bright red fluid and clean pan shouldn't be serious. Fluid dark brown or black, bad smell, lot of sediment or metal in the pan then the transmission is probably worn.

 

[Mont91]

Could just be wear. If it is it might still go another 100k. Might have done it since new. Anymore info?

 

[towcat]

This is my first post so correct me if I am doing this wrong. My 87 C-6 transmission (135,00 miles) doesn't engage right away when cold. You have to put it in gear and wait until it seemingly gets pumped up to pressure before the truck will move. What could be possibly wrong? After it gets warmed up it seems to work ok. Thanks for the help!

your convertor is draining back. to confirm, check your dipstick before starting up to see how high the fluid level is in the trans.

 

[CGriffith]

Yup, converter drain back. I have a C4 that has been doing that since I got it and it's still going after 30k+ miles of me beating on it. Just got to remember to wait for it. I thing bad things might happen if you gave lots a throttle before it made some line pressure.

 

[rparker]

Most auto tranny's do not pump in park. I was told years ago by an old rebuilder that
the best way to start an engine was to put it in neutral, then crank. Nowadays, I
start in park, and immediately go to neutral and let it run for 30-60 secs to make sure
I have pressure before engaging the tranny.

 

[Mont91]

The pump is driven by the torque converter, so if the torque converter is spinning the pump is pumping. To verify this take the output cooling line off and watch it spray in park. It is possible that some of the earliest autos were set up differently but not to my knowledge. This is for car and light trucks, medium/heavy trannys might be different.

Does anybody know of a tranny that does not use the converter to spin the pump?