92 Ex blows off vacuum hoses-Ideas?

[hsinc]

My 92 sport 4x4 4.0 automatic, will on occasion blow off several of the vacuum hoses at start up. I've replaced all filters, the car runs good (unless a vacuum hose is off), it gives reasonably good economy, doesn't burn oil. Truck has 127K miles on it. Any ideas on why this would happen? Something must be allowing engine compression to get into the vacuum side at start up.

Thanks for any ideas.

Harold

 

[Msupertek]

Ford Senior Master Technician

It's your vacuum modulator valve on your transmission. Its located on the Passenger side of the Transmission near the rear. It allows trans fluid to get into the vacuum line causing the lines at the intake manifold to swell up and fall off. I have probably put on a couple hundred in the last 7 years for that same concern. Get under the transmission and pull the vacuum line of the modulator valve to see if tranny fluid is pouring out, if it does replace it. Be sure to put the small rod back in the new modulator valve when replacing or you'll be in for trouble.

 

[hsinc]

Thanks, I'll look into that. I was theorizing a bad EGR, or valve, etc. Hopefully it is the vacuum modulator. Car does run fine and shift fine.

Harold

 

[hsinc]

Msupertek,

If you are still around. Problem had not occured for several monthes. Then it happened again recently twice. I had replaced PVC valve, cause it needed it. The new PVC valve is totally full of oil.
I can not locate the vacuum modulator. Were they for sure on all 92's?
Today when it blew off, a lot of smoke came out of engine hoses (not exhaust). Probably burnt oil in the engine.
I think I'll run by the Ford dealer and try to locate the modulator in their parts catalog.
Because the problem had not reoccured, I've let it go. But now I need to do something about it.
With all hoses connected, engine runs great.

Thanks,

Harold

 

[MrShorty]

Modulator is on the transmission. Sometimes the diaphragm in the vacuum modulator develops a leak, allowing ATF into the vacuum hoses and intake. ATF causes the rubber hoses to swell and lubricates them so they fall off. And the only '92's that wouldn't have a vacuum modulator are the manual transmission ones.

 

[hsinc]

I found the modulator. Very difficult to see. It is between catalytic converter, and transmission. The transmission also has a heat shield bolted over it, covering the modulator.

It appears you have to drop the catalytic converter, to be able to remove the heat shield, before you can access the vacuum modulator.
I hate working on old exhaust systems. Original, but still good.
May take in in and have the modulator replaced.
Harold

 

[lostcajun]

THE EASY way to get to it is go at it through the floor. pull back the carpet, remove the access plate and there it is. pass. side. pull off vacuum hose, remove bolt [10mm?] and pull it out. msopertech is right, dont loose the small rod in the tip of it. good luck. hope this helps.