94 Explorer vacuum modulator


Old 11-15-07, 04:30 AM
Thread Starter
Join Date: Sep 2007
Posts: 58
94 Explorer vacuum modulator


I've recently had a problem shifting into second gear on my 1994 Explorer 4X4; it does shift but at a higher rpm and seems to happen only when cold on the first shift to second gear. Once I get past that it shifts fine. Fluid and filter are new and full. I'm thinking that it may be the modulator. Two questions: 1) Any idea if I can run it like this for a month or so or will (if it is the modulator) it possible just stop shifting from first to second? Is this urgent that I change it soon?
2) How do you change it? I believe that I know where it is but it looks like the location will make it difficult to get to. Does it screw in?
If you believe that it's not the vacuum modulator what could it possibly be?
Any advise would be appreciated.

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Old 11-15-07, 06:34 AM
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,686
Frequently (but not always) when a vacuum modulator is at fault, if you run the rpms up a little in the gear that balks at shifting, then let off on the throttle, it will shift.

The modulator is either hanging up or leaking and the extra vacuum created by the letoff will shift it.

The diaphragm is usually held in by a clip and one bolt, fairly easy to get out and install, and not too expensive (about $25.00). I would change it out rather than run with the problem.

Hope this helps,

Old 11-15-07, 09:21 AM
Thread Starter
Join Date: Sep 2007
Posts: 58

I'll give it a shot; that doesn't sound too bad,
your input was helpful,

Old 11-15-07, 08:40 PM
Join Date: Nov 2007
Posts: 17

Fluid? Did you splash, filter, and fill? Or did you have your favorite repair facility do a trans flush? In a flush they would have hooked up your vehicle to a machine through the trans. cooler lines and run ATF through this machine while the engine runs to keep the fluid warm/hot to achieve a complete replacement of fluids. Furthermore, there are options with some machines to freeze the service and take down the pan and replace the filter while the machine holds the fluid. Also, some companies will add an agent to the trans. before the service to lossen things up in the trans and run it for a period of time. Would highly recommend doing this before chasing component replacement.

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