Ford 3400 Select o Speed PTO

Stewa123

New User
Last winter I attempted to fix the steering shaft leak on my 1969 3400 SOS. This involved removing the PTO cable to get the tin out of the way. When reconnecting the PTO cable the connecting rod had (unknowingly) fallen out of the pilot tube on the transmission cover. So thinking my 25 turns of the cable (per the manual) and measurements thought things were ok. I could never tell when PTO engaged unless it had a load on it and it always windmilled. Sohooked the brush hog a few weeks back and nothing. Ended up removing the transmission cover and found the rod disconnected. Rod linkage to control valve is good. Feathering valve piston moves freely. Have it hooked back up correctly with proper rigging per manual and still nothing. PTO has worked and only thing done was disconnecting the cable. Transmission is shifting fine. Oil and filter changed last summer. ( Ambra multi g134)
Emailed Dave at Arthurs and talked about shortening up the cable rigging which we tried.still nothing.
Feel like Im missing something or did the pto just die over the winter?? It is the 540 single speed.
Any thoughts or tips?
Thanks in advance!
 

I'm guessing something came apart in there if you ran the tractor much with the PTO disconnected.

I suppose it's possible that the PTO just died over the winter, but I don't think that would be very likely.
 
I wondered about it not connected too but after having
my head under that cover not connected would just be off.
The plunger goes in when cable is pulled.
 
The PTO clutch didn't just die over the winter, especially if the rest of the trans still works good. Sounds like you still have a situation
where the cable is not grabbing the internal plunger. When you put the cover on, are you using the short shifter cable as a pilot?

When you thread the PTO cable in, keep going until you feel the whole assembly tighten up. If you can't reach that point, you haven't started
threading into the plunger rod in the first place.

If it does bottom out, loosen it up until you can pull the conduit up and away from the transmission pilot maybe an 1/8 inch or so with the
PTO handle in the engaged position. That should be about right.
 
Did that again yesterday. Tightened until couldnt go any more and could confirm the rod was up against the guide tube with the cover still loose peeking under it.
Put the cover back on and backed the cable out a little. Less than an 1/8 at the bottom. maybe only 1/2 to 3/4 travel at the top. Still had nothing.
Wondering now if the oil pressure is just not getting to the pto pack.control valve or the line down to it leaking?
Reading in one of the manuals about the #2 servo pack pressure. Says pull the pto on and if pressure drops pto circuit is leaking. Its just a note in the troubleshooting section.
I agree though I keep thinking about what I did wrong in rigging but not solving anything.
 

Cable not tight enough? I like mine a bit tighter than Bern does. I turn it, with the T handle in the engaged position, until the conduit is snug against to transmission boss. Then go the closest direction to get the T handle lined up correctly..

Then again, if you've only got 1/2 to 3/4 travel on top (I'm guessing that's inches) your cable is way to tight or something is wrong in your linkage under your cover.
 
Something is wrong with your installation process. You should have nearly 1-1/2 of handle travel when everything is working normally. The
fact that you don't even have half of that tells me that the control valve is not being fully engaged.

You can tell if the PTO is being engaged by watching a pressure gauge in any of the servo locations. Simply watch the gauge while you quickly
pull out the PTO lever. You should see the needle dip for a half-second or so and then come back up to where it was. No movement of the
needle means no oil going to the PTO clutch pack.
 

So cable not tight enough like Larry mentions is what I got from Dave at Arthurs so why I went with just a fraction (less than 1/8 inch off of fitting) and 1/2 inch of travel. That made the cable shorter to ensure Im pushing the plunger on the control valve. This was just a few turns off (5 maybe?) of the cable being fully tight in the off position. So would think that would make it too tight and engage at start up and not being able to disengage would be a problem. Ive been all over with the adjustment. Too tight and too loose.
As Bern mentions I have had it rigged with the 3/32 at the bottom and 1 3/8 to 1 7/16 travel as stated in the manual with no luck.
The travel was always shorter (less than 1 3/8) since Ive had it and thought thats why it windmilled some.
Had a good look again yesterday at the linkage to the plunger and all seems ok. Pull up on the connecting rod and plunger moves in and out freely.
Will have too rig up a gauge just to see what pressure does.
Can you run this without the top cover on? How much of a mess would that make? Feel like I just want to push that plunger on the control valve with it running to prove its not my cable rigging.
I do appreciate your input!!
 

Back in the day it seems as though there was a partial cover, maybe even plastic or glass one could put on there to see through and still adjust valves. If you run it without a cover it will throw oil everywhere in a big hurry.

As far as the PTO "windmilling", that's normal for the SOS as it has no PTO brake. Does it not windmill now? If not, I'd guess something is seriously wrong in your PTO system other than the control cable and valve.
 
You can run it without the top cover in park and at idle speed without making too much of a mess. Since the PTO is the only thing you're
troubleshooting, there's no need to shift it through the gears.

To do a pressure test however, you'll need to be in neutral since none of the servos are pressurized in park. You may wish to have a suitable
piece of cardboard ready to cover everything except the control valve, since I would strongly recommend that the rear axle be disconnected
while you're doing your testing. At that time, when the trans is in neutral, you'll see some windmilling going on that will throw a little
oil. Again, if you're at idle, the amount will be minimal.

As Larry said, windmilling of the PTO is completely normal on a SOS trans, although when the oil is good and warm some of them can and will
come to a complete stop at idle.
 

It does windmill now as it always has. Will come to a stop as the brush hog gets in some weeds. And yes it does (did) less windmilling during weed cutting as it warmed up like you mentioned.
I will get a gauge rigged up and see what I got. And maybe get brave and try without the cover. I got some plexiglass might see what I can do with that
Ill report backthanks again!
 

We did get a gauged hooked up at servo 2. Had just under 200psi and when pto handle pulled could just see a flicker of needle movement. (0-300 psi gauge)
Not sure if thats telling me anything.
Took the bolts off the cover with cables hooked up and was able to sneak a snap-on borescope camera under there. Could see the plunger moving when pto handle moved but I think the plunger should be compressing more. Got a screwdriver in there and could push it in another 1/2 inch beyond what cable was doing. The inching pedal plunger is compressed fully and in reading the manual sounds like they are the same.
Played with the rigging again and could change the travel of the plunger but could not get it to compress further. Rigging back at manual measurement 3/32 or so at bottom and 1 3/8 at handle.
Still need to run it and push on that plunger somehow to get this rigging off my mind.
 
If you could push the PTO valve in another 1/2 inch with a screwdriver, you definitely have an issue with your cable/conduit/handle. Time to
pull it completely apart and find out where the hangup is.
 

Yep will pull it all apart again to see where we are losing that travel. Fun stuff but gives me some the pto itself is ok.
 

Well did get it back apart and the cover off again. Nothing seems wrong with rod and linkage under the cover. Pretty simple linkage. The limiting factor in how much that plunger depresses into the control valve is the connecting rod bottoming into the pilot tube on the cover. Used the short cable from the shifter and with the borescope camera could see it compressed about the same as with the pto handle cable. With the cover off it travels further of course. Would still like to push it further in when running to see what happens but not looking like thats the issue.
Had some hope for awhile but looks like its a tractor with out a pto for now. Will rig it up again and see what happens.
If something changes Ill post it.
 

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