Automatic trans (4R70W) issue

[fastpakr]

I'm running an Explorer 4R70W behind the 5.0 in my '99. For the first year it worked fine (a little hesitant to downshift, but otherwise as good as any other automatic I've dealt with).

Starting a couple of months ago, it occasionally revs freely for a moment when trying to accelerate from a stop or very low speed. To be clear - it's not slipping. It spins completely free as if it's dropped into neutral. After a second or so, it will engage and function normally. If you don't release the accelerator quickly, that sudden engagement will come with a hefty chirp from the tires. This behavior has slowly increased in frequency and it's time I dealt with it. Other than this, it continues to shift fine. I'm still daily driving it and regularly put 2-300 miles a week on it.

From a bit of searching, my impression is that it's related to the valve body. Either a leaking gasket between the VB and transmission or one of the check balls is sticking occasionally. But automatics are uncharted territory for me. I do have a spare VB (two, actually) on transmissions in the storage unit. I don't mind pulling one of those to put on the Ranger, though I'd need some clarification on what precautions I need to take before removing to avoid check balls flying all over the place.

Can anyone point me in the right direction or suggest other troubleshooting tests?

 

[franklin2]

Most of the time when this has happened to me, the oil was a little low in the trans. Pulling away from a stop or going around a curve the oil would slosh to the side and it would go into neutral, and then pop back in when the oil came back to where it belonged. Checking the dipstick, it was always a little low. Adding some back up so it read correctly on the dipstick always cured my problem.

 

[fastpakr]

Most of the time when this has happened to me, the oil was a little low in the trans. Pulling away from a stop or going around a curve the oil would slosh to the side and it would go into neutral, and then pop back in when the oil came back to where it belonged. Checking the dipstick, it was always a little low. Adding some back up so it read correctly on the dipstick always cured my problem.

I'll go back and check today... There's a non-zero chance that I jumped the gun by posting this and not checking the fluid level recently. That would be an embarassing outcome, but an easy fix.

 

[rusty ol ranger]

I'll go back and check today... There's a non-zero chance that I jumped the gun by posting this and not checking the fluid level recently. That would be an embarassing outcome, but an easy fix.

Ive had C6's do that when low on fluid. If it gets better as it warms up id about bet on that being the case.