The mystery of the failing tram seal

[Wyenot]

Greetings PTers both great and small. Settle in now for a tale of two tram pumps and multiple seal kits, that at this time has no sure resolution. The setting for this tale is a small village near Chattanooga TN called Ooltewah. Go ahead boys and girls just try and pronounce that one and better yet say it 3 times fast.

In that village was a man who had a double lot with plenty of trees and about an acre of lawn, some of it flat and a goodly amount of it sloped. The man thinks to himself a lawn tractor will be all that I need to keep this lawn at bay and being the frugal sort decided to get himself a used JD lawn tractor to mow with and maybe drag a few implements with. This he does and is pleased with himself and things go well for him and he sets his sights on happily ever after.

As they like to say, “ into ones life a little rain must fall.” Well happily ever after was interrupted by a series of tornados that raced through north Georgia and west Tennessee. One of the smaller ones decided to visit his property, sparing the house with minor damage , but knocking down most of the pines and some other hardwoods on his adjoining lot.

After helping his neighbors cut themselves out of the fallen trees he was at a loss as to what he could do about the trees that crisscrossed on his lot. In steps a coworker who lets him borrow his PT 422. Needless to say the 422 had its work cut out for it, but it performed admirably during the short time he was able to use it. His friend had taken a job elsewhere and the 422 followed him.

So, the man started to look for a PT of his own. He tracked down the power track website, but the new ones were just too expensive to consider for such a small property, but he really wanted one so he searched the used market. Eventually he found one in the far north in New Hampshire. He grew up there, and decided to see if he could acquire it while on a family visit. He was elated when he was able to trailer it and a bucket attachment back home within his budget. He even stopped at Tazewell to grab a mower and grapple to suite his needs.

Said PT was of the 425 verity, so he had even higher expectations of ability and durability, since it had two steering rams and a larger engine. “Commercial grade. Yeehaw!” Getting to work he set about cutting and grappling the downed trees in his lot. He got the impression that the 422 seemed to have worked better especially going up slopes. Then one day he was having a little PT pucker with a root ball and he noticed fluid on the ground. Not a little, ALOT! So he dropped the load and hightailed it back to the nearby garage, leaving a swath of vital hydronic fluid trailing behind him.

Upon inspection it wasn’t a hose, the oil was leaking from the tram and mount. With only 397 hour on the clock, Disaster! He had read of the dreaded tram pump failure on TracorByNet and here he was beholding it with his very own eyes. Only thing to do is call Terry and send in the tram for rebuild. The wizards at Tazewell did the deed and with the expected steep price. The man told himself “Self, this is the worst that could happen, now your tractor will be just like new, with a rebuilt tram at its heart. The man carefully reinstalled the tram with surgical cleanliness, then he primed the pump and got back to work.

PT worked like a champ for the rest of the clean up and the man again started to glance towards that “happily ever after” again. The PT was doing the job, mowing and pretty easy tasks like flipping over the leave piles for compost when low and behold it happens again. Only 425 hours on the clock. What the.....? The man was dumbfounded. How could this be? He did everything the was supposed to. Replaced the filter and primed things as he should, why did this happen? Of course these things always happen after 5:00 on Fridays all he can do is berate himself on something he messed up that caused the new failure. This time It will be fixed the right way, so he loads the PT up and heads to Tazewell. The man explained to Terry what had happened on the phone, but Terry didn’t understand the nature of the leak. When he decided to drive it in to the service bay, he left about gallon of oil on the ground on the way.

After cleaning up the spillage. They gained access and decoupled the tram to check the seal. Sure enough it was gouged and the metal was tore up. He suggested that some piece of debris got up behind the mount and took out the seal. The man thought, I guess that is possible. I did use a blower to clean out the tub last time I used it. No more of that. Terry replaced the seal and back to TN the man went. Happy he was never going to have that happen again.

Yeah right! Just mowing the lawn. Come on now! That is not abuse! But there it was, oil all over the driveway and following his last run up the yard. Tell me now. Is mowing that strenuous that it would cause the seal to fail again at 459hours? Same 4.5 hour trip to Tazewell. Must be a bad seal this time.

Watching for it now. Heart trembling every time the man does the lawn or starts the PT. Is it something in the lines? Is it a bad pump? Wheel motors? What what what.

487 hours on the clock and the man brings it back to Tazewell again. The job was leveling a lawn and putting grass sod. Just a small load of dirt. Here are the pictures Terry.

Just fix it, please. It stays there for a week. He picks it up and is told that the pump was swapped out with a different one. They checked the tank and the return hose for obstruction. The man goes home hoping against hope that it will be the fix....but is it?

Nope. 519 hours and it happens again. Just arranging a few of the implements to get at the mower. Yes. Terry it’s me again. I have no idea what’s happening. I can’t travel to Tazewell Corona Virus you know. Can you send me a seal?

We replaced the pump right? Yup. I will check with the engineers and see what they say. The seal is just a bandaid though. Yup. Send it anyways. Yours is the only one of the thousands we have sold doing it. Yup, I know.

This is the mystery of the failing tram seal. Anyone have any ideas?

I can’t have the engine looked at until they open businesses back up. All you guys that are at home and bored. Here is a puzzle to keep you occupied. Thanks.

 

[MossRoad]

Yikes! That's awful. Keep us informed.

 

[Wyenot]

Hi Moss. I noted that 69 people viewed my story. Was hoping there would be more ideas posted. I tried to make the post as light hearted as I could, but man it sure is disheartening. Terry talked with the engineering guys and they have no clue as to what is causing it. From what I understand of the system the area of the pump effected is not a high pressure area, as the flow is going back to the tank. With a filter at the suction side nothing should get into the system. Maybe the prior owner had some work done and they didn’t flush the system out enough? Maybe what ever it is gets sent back into the wheel loop where it gets stuck for 20-30 hours then gets loose to damage the seal and return to the wheel loop? Seems to me that something sizable enough to damage a seal would damage the wheel motors or the swash plate or something else. The only other thing I can think of is a bad engine main bearing or crankshaft out of true, causing enough oscillation to destroy the seal. It just takes a few hours for it to finally self destruct. I don’t have tools needed to test that. 500 hours seems like a low number for that, but who knows. Is it feasible to put some kind of filter in the wheel circuit return line to catch anything there? What if the inside of a hose is breaking off from age? Maybe bending in the tunnel when turning sharp loosens it up and then... The hoses look good from the outside. No signs of dry rot.

 

[flyerdan]

Not being familiar with the architecture of a PT, it would be interesting to see a good close up of the failed seal, front and back. It seems to me that something fairly egregious has to be there to make a seal fail so fast; if it was a scored shaft or burr causing it that should have been caught right away. If the outside of the seal is exposed, it is possible that it could have picked up something, like an outboard will wind up fishing line and ruin a seal, but that should he apparent on initial inspection, and not happen repeatedly so often.

 

[MossRoad]

Hi Moss. I noted that 69 people viewed my story. Was hoping there would be more ideas posted. I tried to make the post as light hearted as I could, but man it sure is disheartening. Terry talked with the engineering guys and they have no clue as to what is causing it. From what I understand of the system the area of the pump effected is not a high pressure area, as the flow is going back to the tank. With a filter at the suction side nothing should get into the system. Maybe the prior owner had some work done and they didn’t flush the system out enough? Maybe what ever it is gets sent back into the wheel loop where it gets stuck for 20-30 hours then gets loose to damage the seal and return to the wheel loop? Seems to me that something sizable enough to damage a seal would damage the wheel motors or the swash plate or something else. The only other thing I can think of is a bad engine main bearing or crankshaft out of true, causing enough oscillation to destroy the seal. It just takes a few hours for it to finally self destruct. I don’t have tools needed to test that. 500 hours seems like a low number for that, but who knows. Is it feasible to put some kind of filter in the wheel circuit return line to catch anything there? What if the inside of a hose is breaking off from age? Maybe bending in the tunnel when turning sharp loosens it up and then... The hoses look good from the outside. No signs of dry rot.

You can't put a filter on the return line from the wheel circuit, because there is no return line from the wheel circuit. There's two ports on the tram pump. The fluid flows in either direction through either port, depending on the angle of the swash plate. The angle of the swash plate in the tram pump is dependent on the position of the directional pedals. If you put a filter on one or both of those ports, it would just be washing the filters in and out every time you changed direction, I think.

As flyerdan mentions, someone has to examine those seals and try to determine where they're getting damaged. With that many, that fast, I'd be leaning towards:

- a bad batch of seals
- or incorrectly sized seals
- or incorrectly installed seals

 

[MossRoad]

Or something is flying out of the lovejoy connector with centrifugal force along the shaft and gouging the outer seal, then snapping back in as the engine RPMs slow down? I know that's reaching, but it should be checked if the seals are getting gouged out from the outside. The only access is around the shaft, the lovejoy connector. And that's assuming there is a lovejoy connector in there, of course. The lovejoy should be keyed onto the shaft. I wonder if the key is sliding in and out against the seal? Is that even possible?

Just scratching my head at this point. :confused3:

 

[flyerdan]

I can't imagine it being the key, as that would mean the keyway was cut beyond where the seal runs, which would be an opening for oil to flow through, as well as a cutting edge on the seal.

 

[marrt]

OK, this is an interesting one for sure.

1. First, what tram pump do you have? Don't know?...take a picture of the pump and post.
2. What seal, exactly, is failing? Is it a seal in the pump itself, where the pump connects to the motor, where the pump connects to the steering and PTO pumps?
3. Did you call the original owner and ask any questions? He may be reluctant to admit anything, but it's worth a try. It would be interesting to know if he had the problem for a while. Maybe a mating surface was not properly machined on the motor or other pumps. I'd also ask if he ever replaced any hoses, motors or pumps.

I have a hard time thinking the seal failure is due to contamination. Unless the relief valves are sticking, creating a high pressure spike. You can build a "filter cart" for a few hundred dollars. I've posted a picture on here as to how the plumbing works to ensure the fluid always flows in the right direction through the filter regardless of how it's hooked up or traming direction. You take one hose lose at a wheel motor and connect the filter assembly in line. I built one using a high pressure filter with a 3 micron cartridge. Work good. Ideally, ever time the wheel circuit is opened up the fluid should be filtered after reassembly. That's proper technique.

 

[Wyenot]

Good evening everyone. Thank you for the posts. I did reach out to the prior owners, as they were listed inside the cover of the Manual that came with the PT when I purchased it. They used it in their nursery business, but went to a skid steer and it just sat around, so they traded it. They denied having any issues with it. I purchased it from the dealer at a reasonable price, not too high or low that would indicate it had issues.

Terry replaced the seal under warranty several times as he wondered if it was a bad lot, but the last one he put into my original tram pump, was from a new bag with a different lot number. When he replaced the tram with a completely different newly refurbished pump, he also replaced the lovejoy connector and the bell housing. There was no indication that there was any burs or anything on the drive shaft that would cause it to fail. They made sure the return line was not obstructed and hoped to say goodbye to me and the problem for good. Unless I was buying something new of course. The second seal could have definitely been from debris getting in between the engine and the tram pump bell housing. I admitted that at that point, but no such debris could happen again. I no longer use a leaf blower in the engine bay, and I put a fine screen over the back of the tub to keep debris from being drawn in by the engine. The opening the debris can get into and around the shaft is less than 1/4 inch as well, so it is very unlikely. I will post close up pictures of the seal before and after I get it out, along with the pump itself. Replacement is fairly straightforward. Gain access to the pump area remove 4 bolts holding the bell housing, disconnect the lovejoy from the shaft, then pull the snap ring and pick out the old seal. Unfortunately I have seen it done one to many times.

@ Moss, your right, now that I think about it. Unless you set up a cage like was described the flow would be just like A/C current flowing both ways in the circuit. I will still have to have the engine checked to rule out a bottom end problem. Crank wobbling or excessive run out? All I can say is...I love the thing when it is running right, but it sure does test your Christianity, when it don’t. Makes you want to chew 10p nails, when it does these kind of things, or gives you the air lock. Thinking about replacing all the drive hoses, draining the tank and starting over with fresh fluids. Anyone have any good ideas on how that would be best done without causing damage from cavitation?

 

[johara1]

Good evening everyone. Thank you for the posts. I did reach out to the prior owners, as they were listed inside the cover of the Manual that came with the PT when I purchased it. They used it in their nursery business, but went to a skid steer and it just sat around, so they traded it. They denied having any issues with it. I purchased it from the dealer at a reasonable price, not too high or low that would indicate it had issues.

Terry replaced the seal under warranty several times as he wondered if it was a bad lot, but the last one he put into my original tram pump, was from a new bag with a different lot number. When he replaced the tram with a completely different newly refurbished pump, he also replaced the lovejoy connector and the bell housing. There was no indication that there was any burs or anything on the drive shaft that would cause it to fail. They made sure the return line was not obstructed and hoped to say goodbye to me and the problem for good. Unless I was buying something new of course. The second seal could have definitely been from debris getting in between the engine and the tram pump bell housing. I admitted that at that point, but no such debris could happen again. I no longer use a leaf blower in the engine bay, and I put a fine screen over the back of the tub to keep debris from being drawn in by the engine. The opening the debris can get into and around the shaft is less than 1/4 inch as well, so it is very unlikely. I will post close up pictures of the seal before and after I get it out, along with the pump itself. Replacement is fairly straightforward. Gain access to the pump area remove 4 bolts holding the bell housing, disconnect the lovejoy from the shaft, then pull the snap ring and pick out the old seal. Unfortunately I have seen it done one to many times.

@ Moss, your right, now that I think about it. Unless you set up a cage like was described the flow would be just like A/C current flowing both ways in the circuit. I will still have to have the engine checked to rule out a bottom end problem. Crank wobbling or excessive run out? All I can say is...I love the thing when it is running right, but it sure does test your Christianity, when it don稚. Makes you want to chew 10p nails, when it does these kind of things, or gives you the air lock. Thinking about replacing all the drive hoses, draining the tank and starting over with fresh fluids. Anyone have any good ideas on how that would be best done without causing damage from cavitation?

How do line up the pump after you have it apart?there is a way to do it..... jim