built67

i may have a bad pressure modulator in my tranny bc its been sitting and the p.mods are made outta plastic i was told...are they a big pain in the *** to change? and where are they located??...i was told on the side of the tranny. thanks.

my77stang

you mean the vacuum modulator? thats metal with a diaphram inside, and they are located towards the rear of the transmission and should have a vacuum hose coming off the back of it.

when you take the retaining clip bolt out just pull on the thing and it will come out. beware of tranny fluid that will surely come out with it and get all over you, and there is a little metal rod behind the modulator that may or may not come out with it. its about the diameter of a clothes hanger and about 1" - 1.5" long

*edit* the above info is for a C4

jlg2002

You really need to know what it is that is wrong. Just because it sits doesn't mean something goes bad. It the car drives and shift well, don't mes with any thing! (unless of course you have a tranny fluid leak)

built67

idk a guy at a shop near my house told me it's called the pressure mod. and it's plastic. and jlg, it sat for 6 years, runs great but i have not breaks and when i put it in drive it doesnt go anywhere for a bit then the tranny catches then slips again and leaks fluid. idk where it is coming from but my whole transmission even the bottom of the pan was soaked with it.

built67

i think that it is the vacuum modulator. i thought before that it was my rear seal but i was able to jack the back of the car up and fiinally got my first look. all around the rear seal and the driveshaft and yoke is all dry, and if it was leaking that wouldn't be the case. There is a small piece towards the back that is fully soaked with fluid tho. It is a small metal piece that sits on the side. and then there is another big piece that site on the upper side that is bolted on. any ideas what those are? im asking because i really don't know transmissions that well. thanks.

jspagna1

This is what I think you are talking about. I just changed mine. Had no trouble with the trans, but there will sometimes be white smoke coming from your exhaust that will tell you trans fluid is leaking into the motor. That was the indication on my car so I changed it. And what my77stang said will happen. Make sure you don't lose that pin or have it fall into the trans or you will have to remove the pan.

You mean the vacuum modulator? thats metal with a diaphram inside, and they are located towards the rear of the transmission and should have a vacuum hose coming off the back of it.
When you take the retaining clip bolt out just pull on the thing and it will come out. beware of tranny fluid that will surely come out with it and get all over you, and there is a little metal rod behind the modulator that may or may not come out with it. its about the diameter of a clothes hanger and about 1" - 1.5" long

This is probably what you need.
http://www.transmissionpartsusa.com/...-00025900a.htm

built67

ohhh ok, because my car used to smoke a lot of white smoke when i would run it, but then i changed the tranny pan gasket and filter and havent put new fluid in it yet, and when i run it now there is no smoke...so that would mean tranny fluid is leaking into the motor? and that would be caused from the vacuum modulator?

built67

i called up NAPA to order a new vacuum modulator, and they said i need to let them know what color stripe it has around it. when i take it out, there will just be a strip around it?