The Stovebolt Site Forums The Parking Lot Big Bolts transmission pto seal leak?

So I found the leak that is draining my transmission oil. It is seeping out of the pistion that engages the pto. On the side of the transmission, next to the PTO output, is a small cylinder that engages the PTO. The oil seems to be leaking out around that piston. Any suggestions on how to fix this leak? Will this piston just slide out when I disconnect the linkage? Is the seal something that will be easy to replace? I'd just like to have some idea what I am getting into before I start tearing it appart... famous last words, right?


Thanks in advance!

Mine leaks a little too. I'd like to piggy back on this question...

The PTO is pretty striate forward. Drain your transmission remove the pump drive shaft the cable or linkage witch ever it may have. Then remove the six bolts that secure it to the transmission and take it to a good clean work bench. Note how it comes apart and disassemble it. If this makes you nervous mark the pats as to how they go with an engraver and take a few pictures of the disassembly process it is pretty simple. The seals may be lip seals or possibly orings or even quad seals. Take the seals and there mating surfaces to a bearing house and they can get you replacements. Also clean and inspect the bearing to determine if you want to replace them at the same time. Remember to get gaskets for between the transmission and the PTO they will come in different thickness get a couple of each. Carefully reassemble you PTO in the reverse of the disassembly. Now when you reinstall your PTO you will mix and match the different thickness gaskets you got till you get 6 to 12 thou backlash between the PTO gear and the gear that drives it in the transmission.
I hope I didn't make this sound too complicated it's not.

Thanks HevyHauler - it sounds do-able and I appreciate the detail... but first I gotta find where all the gasoline is comming from under my truck!

On a truck that old there is no "piston" on the PTO you describe. It is mearly the shift fork and slides in/out by the lever it is attached to. There is nothing else inside the PTO except the gear which slides on it's own shaft to engage to or disengage from the drive in the tranny. Try one of the Chelsea PowerDrive dealers in Portland.

Be sure to replace both seals while you have it apart. The PTO gaskets come in many thicknesses so measure (mike)what is on it an replace to same thickness to ensure the proper backlash. Check the studs while it's off too, cheap insurance.

Here is a picture of the "piston" that appears to be leaking.

http://i149.photobucket.com/albums/s50/ccogg/pto.jpg

I know the oil looks bad, I just took the top cover off the transmission today and flushed it out, then refilled it with fresh oil.

Also, here is a picture of the transmission when I had the cover off to clean it out.

http://i149.photobucket.com/albums/s50/ccogg/transmission.jpg

ccogg,
Mine appears to be different model:
http://picasaweb.google.com/orchidskip/LeakyPTO?authkey=cdCB8fzuJsE

ccog: Looks to be a pretty old Chelsea or possible a Spicer brand PTO. They are now combined as Chelsea under the Parker Hydraulics banner. The seals are fairly common. This model was designed as a lever shift unit even tho' someone has adapted a cable to it. The floor mounted shift lever was the advantage it used to make shifting it easy.

orchidskip: Yours is a much later Chelsea double gear unit. That "round thing" is a freeze plug I think and very simple to repair. This model was designed as a cable shift PTO and used the short lever to gain mechanical advantage. It is a much heavier duty model than the single gear types and is usually found on heavier transmissions with a lot of torque on the driven gear.

Incidently, FWIW, the early Muncie brand PTO's up thru the eighties were actually Chelsea's and were assembled, branded and sold under the Muncie tradename. They are now all aluminum and are of Muncie's own manufacture and owned by an Italian company. At least they aren't Chinese or made in Mexico. I think?

thanks Dave. Can I maybe pop out that plug and replace it without pulling the unit and where on earth does one get a little freeze plug like that?
Skip

Your local FLAPS should have an assortment of sizes or they don't deserve any of your money.

orchid skip. that looks like the end of the mainshaft, that one is a two shaft unit with either forward reverse, or two speeds. it probably has an oring on it..
ccogg your looks just like a lip seal... clean it off and read the number...remove the linkage and pop out the seal and replace, no need to remove pto..

Sorry to disagree with you fatweed but orchidskips PTO definately is NOT a forward/reverse OR a two speed unit. It is as I said a two gear design and extremely common. Parts available at any PowerDrive distributor or truck equipment house. Two speeds and F/R PTO's are very large, twice the size of this unit and cost as much or more than the transmission. Generally are 8 bolt design too and this tranny only have a low torque rated 6 bolt opening.

It looked like the end of a shaft to me too but Dave, I hear the ring of conviction in your statement so I am convinced. I'll try to find a wee freezed plug for that thing. Not sure how to remove that old plug. Maybe drill a hole in it, stick a slide body hammer in the screw hole and try to pop it out that way? It works great and nothing else seems to be leaking so I'd hate to remove the unit. You know, if it ain't broke, why bend a wrench? How about if I just put some Bubble Yum bubble gum on it and call it a day?

They do make forward reverse pto's for sm420s in 6 bolt design because ive got one on my truck with winch... also the shaft that is showin in his pics has the dimple in the center where it was centered on a lathe, dont ya think? why the two gear design or two shaft design if not to reverse direction of rotation of output shaft?

The gear that is engaged to the transmission is running constant and the second gear shifts onto it when the PTO is placed in operation. This allows for different ratios and power than can be had by that available directly from the drive gear of the dransmission. It also allows the distance or c/l of the pto shaft to be further from the transmission and makes for a lot more application variations such as direct drive pumps, air or electric shift, etc. Yes, I realize that there are 6 bolt units like you have and I said most or generally they are 8 bolt and that is true.

PTO comes in almost an infinite number of variations. I have worked with a lot of PTO's mostly eight bolt, single speed, direct mount, air shift. Dave knows the older unit for our Old Bolts pretty well but you can't expect anyone to know every odd ball unit ever made. I once built a helicopter fueling truck on an F550 4X4 cab and chasse with a I think ZF6 speed. Had to use 2 30* spacers and grind away part of the transmission case and I don't know how many hours spent on the phone with the PTO supplier to come up with this solution. It was then I learned how many variations there are.

You guys all sound like experts. It LOOKS like the end of a shaft. If I treat it like a freeze plug, that would probably mean drilling a little hole in it to see if I can find a way to extract it without removing the unit from the transmission. I REALLY don't want to remove the unit from the trans. In any event, I'm too busy working on the bed just now. Maybe someone else will weigh in on this until I can get to it later. I'll let you know...Skip

Some units have small freeze plugs and your may or may not. But if it's the shaft end (seems small in the photo for a shaft and is why I think it's likely a freeze plug) then it's the idler gear that is in contact with the trans gear. The drive gear or power shaft gear as it were shifts on/off of that shaft. No matter what just go to a Power Drive Spicer/Chelsea distributor or good Truck Equipment house and get what you need. Take the tag info with you if you have it. Not wanting to remove it means not repairing it.