I was finally able to get the ford project out for a drive today (after rebuilding most of the top half of the engine), and wouldn't you know it, the transmission isn't shifting properly! Fix one thing, another breaks?
What is happening is, if i put it into drive, it won't shift up, manually drop it down into 2nd, it shifts up to 2nd. Start out in first, manually shift up to 2nd, no problem, at 45mph try to upshift to drive (3rd or 4th, not sure yet) and it won't shift until the engines almost to redline, then it shifts hard. also, when it does shift up, it doesn't stay in that gear, it jumps back down, up, down, up down. it seems to have 4 gears too. HUH?
So, I have been reading a number of posts on tranny problems. My questions are:
1) will a 1989 vacuum regulator valve fit and work on my 1985 6.9l IP?
2) did the '85 have an E4OD or not, I thought the transmission was a C6? (next time I'm on my back under the beast I'll count pan bolts)
3) if installing a new modulator (to the passenger side rear of the transmission), how do I set the diaphram properly?
4) can someone please post a pic of the proper way the kickdown shaft is attached to the ip and the drivers side of the transmission?
5) would it be best to put Trans-X in before or after testing/replacing vacuum parts?
6) what have I overlooked or forgotten to ask in this process?
Thanx so much for your help.
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1985 F250 Ext Cab 4x4 C6 auto, 3.73:1 final, 198000 miles, unknown mileage on the engine, 14mpg (city).
How good is the vacuum "inches" in the system.........
85 was a c6 TRANS......
Have you reset the VRV since doing all this work........
How to adjust VRV by James
You don't have the engine running for the test, you need to apply 20" vacuum (Hg) to upper VRV port and attach vacuum gauge to lower VRV port. The lower port is the one that goes to tranny, the upper to vacuum pump.
You have to maintain 20" vacuum (Hg) througout this test. If it drops off you need to pump it back up.
Remove throttle return spring, cycle throttle lever 5 times from idle to WOT. Make sure 20" vacuum is maintained on upper port side.
Move throttle so it is 0.515" (33/64") from wide open (they make a tool for this). Vacuum gauge should read from 6-8" of vacuum (Hg). If incorrect adjust VRV to 7".
Again apply 20" vacuum, cycle throttle from idle to WOT 5 times. Return to idle. Gauge should read at least 13".
It says if you can't get the 7" or the 13" to replace the VRV. If VRV checks out maybe the diaphragm (modulator), line from VRV goes to the vacuum diaphragm I believe. Can't find any adjustment for the diaphragm but I think there is a little.
Basically all you need for the test is a vacuum pump (handheld type), vacuum gauge and a ruler to measure 1/2" or a 33/64" drill bit in lieu of the .515" tool. And a screwdriver for any adjustment needed.
Good Luck
James
Note..... 20" vacuum Hg is equal to MINUS 65 Kpa.....
So, PLC7.3, you are pretty sure it is the VRV that is the cause of my shifting woes? I have read the process for testing/setting the VRV, but as yet haven't had the time and tools together to do the test. If the VRV tests bad, will one from a 7.3l work on my 6.9? There are still other things I am unsure about with the transmission, like the "kickdown" shaft/linkage. Also, when counting gears I should only end up with 3, right? (it seems like a silly question, but that's how weird my trans is acting). Finally, how about the adjustment screw on the modulator valve if the modulator needs replaced?
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1985 F250 Ext Cab 4x4 C6 auto, 3.73:1 final, 198000 miles, unknown mileage on the engine, 14mpg (city).
another thing to check, is on the injector pump, theres a plastic piece that twovacuum lines go into, its on the drivers side of the pump, looking at it. en you if you cross those lines the tranny will act like a TURD and shift randomly, up and down when you dont expect it, its worth checking out before you get into the other stuff that other users have posted. good luck
Its most likely a vacuum problem. Either the VRV is severly out of wack, or there is a vacuum leak in the VRV curuit making the transmission think its at WOT all the time. I had these exact same conditions happen twice when my alternator belt flew apart (vacuum pump is driven off the alternator). Might also be worth checking the kickdown rod in case you may have bent it during the recent work.
Don't put any snake oil in yet. And don't worry, its probably a simple fix that is unrelated to the internals of the transmission.
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1986 F250HD Ex cab Fresh built up 6.9L diesel Lariat AC leather seats power everything w/full cluster, sterling rear 3.08LS gears, E4OD trans, ram intake ATS 088 turbo
1986 F150 Ex cab Lariat rollercam 5.0L on LPG AOD trans 3.55 gears 390 000Ks
since this is my first F-250 diesel, I wouldn't know what the kickdown rod is supposed to look like (as far as bends are concerned, I know the upper portion was disconnected when i got it), so, as per my previous e-mail, pics of the linkage and rod would be appreciated.
The transmission probably has 200K miles on it, and It would seem that is about the service ceiling according to some magazine articles I've come across. In another posting on transmission issues someone mentioned Trans-X, which is why I ask.
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1985 F250 Ext Cab 4x4 C6 auto, 3.73:1 final, 198000 miles, unknown mileage on the engine, 14mpg (city).
If it worked properly before the upper engine work, I'd bet on a vacuum issue.
1: Make sure the vacuum pump is sucking.
2: Make sure suction is getting to the VRV on the fuel pump.
3: Verify suction is getting to the vacuum modulator on the transmission.
If not there is either a split in the line, a break, or it's pinched.
Sometimes the line will touch the pulley on the pump and wear a hole in it and the engine noise hides the sucking sound.
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Gray 1991 F250 standard cab, 7.3, E4OD, 3.55:1, stock wheels and tires.
Verified 19 mpg city taking off slow as hell the shutting down at red lights, and with the radiator grill blocked flush, no bed cover, "drag shoot" mirrors on I get 24 mpg at 50 to 55 mph on the freeway empty!
However, with a bed cover, no mirrors and Hydroxy
Thanks for all the advice. Next question, if I pull the vac line from the modulator and find it broken, what color modulator should I buy? On the parts screen they show different color bands around the base: green, blue, black? what's the difference?
Got a vacuum gauge and vac pump today, I'll test tomorrow and let you know what i found out.
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1985 F250 Ext Cab 4x4 C6 auto, 3.73:1 final, 198000 miles, unknown mileage on the engine, 14mpg (city).
If you do not have oil in the vacuum line, don't worry about the modulator. If it is the modulator, then buy the same color as you have on the truck now.
The Valve off the 7.3 will fit fine, also if it was a E4OD I don't believe it would have a vacuum line, not sure, but I don't think they were vacuum operated. They did not put E4OD until 88
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1997 F250 Crew Cab 4x4
1988 F350 7.3 Crew Cab 4x4 Dually C6 w/ GearVendors Overdrive currently in a deep sleep until motor overhaul is finished. 1984 F250 2 wheel drive 6.9 Extended cab 4 spd manual. (3) 1976 F250 Reg Cab 4x4 All 390, two C6 and one 4 spd.
AndysFords, that's what I thought, but I want to ask rather then guess.
The reason I ask about modulator color is that the modulator is covered in oil, dirt, road grime, and generally looks pretty brown (which is not a color option with the modulator). What's the difference? Is one specific to this year/engine/4x4 v 4x2? thanx
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1985 F250 Ext Cab 4x4 C6 auto, 3.73:1 final, 198000 miles, unknown mileage on the engine, 14mpg (city).
Okay, so I was able to get a vacuum pump and gauge, and found that the VRV was indeed bad. I couldn't hold any vacuum on the unit, when I added a little pressure on the top of the unit it held some vacuum. I would assume that it has a crack in the plastic somewhere, so I bought the one off ebay for an '89 7.3l ($27.95 shipped!). I also took the vacuum line off the modulator and found no leaking ATF, so I am pretty sure the modulator is good. Next week, when I get the part I'll find out if it is enough to fix the problem. Also, with the truck running I tested the vacuum of the vac pump, it showed about 21-22 in/HG at idle-1500 rpm. It would seem that it is working properly too.
Next vacuum question. Is the multi-point connector on the firewall a one way valve? When I turned the truck off and disconnected the vac gauge, there was a slow sucking sound from the front passenger side of the engine bay. I would assume that is the remaining vacuum leaking from other vac areas? good or bad? thanx again
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1985 F250 Ext Cab 4x4 C6 auto, 3.73:1 final, 198000 miles, unknown mileage on the engine, 14mpg (city).
It dropped from 21 down to about 13, but seemed to hold steady at that. Should the vac lines hold 20+ long after shutdown? The sound didn't start until I unplugged the vac gauge. Also, I didn't have the a/c running (the belt isn't even on the compressor).
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1985 F250 Ext Cab 4x4 C6 auto, 3.73:1 final, 198000 miles, unknown mileage on the engine, 14mpg (city).
hay what up ive had sume of your falts but mine were on a c4 but a bad tvcable or the vac modulator could cause this or if you have the tv cable it might be out of adj allso you could go the parts house and buy the book like i did its a haynes ford tranny book cover allmost all the trannys except the new ones c3 threw aod book #10355
Lariat AC leather seats power everything w/full cluster, sterling rear 3.08LS gears, E4OD trans, ram intake ATS 088 turbo
1997 F250 Crew Cab 4x4 
until motor overhaul is finished. 1984 F250 2 wheel drive 6.9 Extended cab 4 spd manual. (3) 1976 F250 Reg Cab 4x4 All 390, two C6 and one 4 spd. 
