Hi, I have a 1988 f250 with a 5.0 engine. Not sure of the trans. I am using a lot of trans fluid with only a very small apparent leak at the dip stick tube. I assumed it was the vacuume mod so I crawled under to check it and cannot find one. The auto part staore shows they have one but I just can't seem to find it. All the other fords I have had It was at the right rear of the trans. I am going through about 3 qts oil per 100 miles driving with no obvious leaks. Leaves a small puddle about the size of a saucer after sitting for several weeks. No leaks I can see when running. Truck is only used for occassional lumber or hardware trips. It seems to shift fine as long as the level is up.

 

Either a C6 or a very very early (troublemaker) E40D..........

If a C6, the modulator diaphragm vac leak can bring trans fluid up to the intake where it gets burned in combustion, then sent out the exhaust.....

 

That's what I figure it is but I can't find it on the trans. Well I found it after my post anyway.

 

That's an extreme amount of fluid going somewhere ---

 

The little vacuum modulator is a common leak cause.

When you replace it, be sure the little rod that goes up into it is still there.