I have a 93 Ford Aerostar. I just had the modulator valve changed out and the front and rear seals put in on the transmission. I took a 640 mile trip and everything ran fine, then after a day of it sitting up, I took it for a drive, The transmission did not want to engage into drive, It had gone in reverse real well backing out of the driveway. After I get it engaged it runs good. I am still having the problem. What could be the problem?

 

I know it's a "dumb question" but did you check the fluid level?
Mine would typically act like that when the fluid was low, add fluid & it was fine.

 

Yes, I checked the fluid level and it was a little low but not much. I topped it off and it still does the same thing. I was wondering if it may be the modulater valve, not telling it when to change gears. I am at a loss.

 

Still sounds like low fluid level. Add another 16oz (half quart) and see what happens. These transmissions are notoriously senstive to low fluid levels. Adding fluid down the dipstick tube makes it difficult to obtain an accurate reading. Add the fluid then check the level the following day after all fuid has drained down the dipstick tube. Measure while the engine/transmission is warm and idling.

 

I let the engine warm up and then check it warm and idling and the fluid level is in the cross marks which it says do not add if in this area. My problem is that I am 640 miles away from the person that put the modulater valve on and replaced my seals. I have no one I know here to check it out for me.

 

A modulator problem shouldn't keep it from going into gear. It can cause it not to upshift properly but it should still go into gear.

 

Maybe I stated it wrong. It goes into gear but it won't upshift as you called it. At about 25 miles an hour it stays in low, I have to gun it and it will go into a higher gear. Sometimes it takes awhile, others it just takes a good gunning. I hate doing that but I do not know what else to do

 

Yes that could be a modulator problem. I would make sure the vacuum line to the modulator is good, and connected at both ends.
A bad governor can also cause the same problem. It is inside the transmission and not easy to get at though

 

thank you so much for your help. I will see what I can find. I do have the old modulater valve in my possession, so I will know what I am looking for. Thanks again.

 

If that small pin fell out of the Modulator it will do that. I have seen many treads on the pin falling out or they never seen it to start with.

 

Racerguy has it right. Why don't you manually upshift it? That'll go around the modulator problem until you get back to the guy that put it in...By the way, anyone can change a modulator, it's as easy as a light bulb, no kidding. Make sure it hasn't back out of the hole a little and the clamp is still in place.

 

"it's as easy as a lightbulb"

Remembering that the "lightbulb" in question is located close to the cat. converter and has a litle pin in there that likes to fall out just as you are tipping the end of it into the "socket", reaching around the converter isn't a big problem, but makes keeping the pin in there just a little bit of a trick.

Mine was leaking so I replaced it a couple weeks ago. I lost the first pin, a local tranny shop made a new one for me.

 

Sorry, I was thinking of a C-6 et al.

 

I found someone to look at it today. The modulator valve was okay, pin in place, vacuum hoses in place. So, I still have the problem. I will put a little more transmission fluid in it tomorrow and see how it works. The one that looked at it said it could be the governor, anyone have a comment on that one?

 

To access the governor you have to remove the extension housing on the back of the transmission. If your van is a 4x2 it's quite easy, if it's a 4x4 you have to remove the transfer case. A sticking valve in the governor can cause the problem. I havent done one in ages but I seem to recall that the last one I did I had to replace the governor as it was too worn to salvage.