I cant seem to figure this out. When the truck is cold it takes forever to shift from 2nd to 3rd, about a mile. I can be gentle or I can run the crap out of it but I cannot control the shift. Doesn't seem to be so bad if I plug it in for a few hours or let it idle for at least 10 minutes. When it does finally shift it is smooth and it will never do it again. TV cable is within spec and fluid is at the full mark and clean. Transmission was rebuilt with a good converter 10k ago. This would be my 4th winter with this truck and the only time this has ever happened.

Any advice would be awesome.

 

when you check fluid is the trans in neutral ?

I would change the fluid and filter.

 

Yes and I drive a few miles and then check it.

 

Second to third show shift could be a plugged filter, or the valve body mounting screws coming loose. (yep, it happens on a 518 behind a diesel.) Plugged filter would be sensitive to fluid temperature for sure.

If you're talking about the last shift (OD) then it sounds like it's working right to me. It's not supposed to go into overdrive until the engine coolant temperature is above 60°. Don't ask me why, I didn't design it, but that is the design.

 

Interesting, no problems with overdrive just 2nd. Doing 40mph at 2000 rpm is strange lol

 

Well, looks like ya need to drop the pan. Put in a filter, and check the screws while yer at it. I think it's the front 2 that loosen up. They are only into aluminum, so don't strip them. Best to use a little torque wrench on them.