Transmission problems

[PaulNeel]

I just took my 65 mustang out of a barn after three years of storage. It used to drive fine, but of course, there are now a few problems. The most concerning issue for me is that the transmission will drop out. I'll put it in drive and it will pull forward, but as soon as i step on the gas, it falls out of gear and acts like it would in neutral. I'm going to check the lines and drain/replace the tranmission fluid, but any idea if my problem is bigger than that? Thanks for your help.

[Oldstyl]

Could be a number of things including a bad modulator valve, dirty fluid, lack of fluid.

Start by draining the tranny, and refilling it. While you have the pan off change the screen filter. Unfortunately on a c-4 the whole pan has to come off to drain the trans anyway.

Also check to make sure the vacuum lines are not cracked or leaking.

Anybody else have a suggestion?

[vamach1]

The fluid may take a while to circulate back every in the tranny. Let it run for ten minutes and with the brake on shirt thru Rev and Neutral and 123. As David suggested - a fluid change might do the trick. County Transmission in Vienna does excellent work if the problem persists.