Hello,

I have a 1999 XLT 2WD with a 4R70W transmission with about 180K miles.

Here is the problem. When trying to get the truck to move after it has been sitting for an hour or more, I usually have to rev the engine to something like 3000 RPM before it will start moving steadily forward. Once it reaches that rotational speed then the transmission kicks in and we take off like a dragster. Also, I can get the truck to start to barely move, but I can feel that it is not fully engaged. There is no power behind it, it barely moves but it will sort of move sometimes. I am not sure if the clutch is just slipping or what. (The oil was really dark but didn't really smell burnt and the magnet did not have a ton of stuff on it when I dropped the pan.) Once the truck is moving it goes fine and shifts smoothly through all of the gears. When it gets to a stop and then we need to go again, most of the time it has no problem getting off the line. It still seems to be engaged when we come to a stop. But if I turn the truck off and let it sit for a while, I will have the same problem again.

The interesting thing is that this only happens in forward and in all of the forward gears. If I put it in reverse with it just idling I can feel the transmission engage and the truck starts moving backward. If I then put it in drive, I don't feel much if any engagement.

I have researched this problem quite a bit and thought I had it narrowed down to a drain back problem. I pulled the valve body all apart hoping to see something wrong with the drain back valve in the valve body. Nothing looked wrong. I cleaned the entire thing and put it back together with no positive results.

When I pull the cooling line off of the radiator and turn the engine on, just at idle, I do seem to have a good and constant flow right from when the engine starts to turn. This gives me the idea that it is not a drain back problem.

The transmission is a black box to me and though I have really tried to study how it works, I don't know what could be causing this problem. I would appreciate any help.

Thanks all.

 

You prob have a torn lip seal in the forward clutch.