Hydraulic motor help needed

[ernemats]

I bought a used flail mower for my 422 and the hydraulic motor for it is leaking at the shaft. The rubber seal around the shaft is worn through in one place. It looks like the seal is held in by a snap ring. The question is can the seal be replaced by just taking the snap ring off and replacing the rubber seal or does the whole motor need to be taken apart? The motor is a Parker the numbers are 00/4, MZG2AB113S1 Made in Italy.. Pictures attached.

 

[PTWannaHave]

Assuming there's a bearing holding the shaft just behind the seal, I would think that you should be able to rip out the bad seal (write numbers or take measurements beforehand) and install a new one that is held in with a press fit...

Someone else with more experience with hydraulic motors should be able to confirm or deny.

Cheers,

 

[KMA]

Here's a pdf with more details on the MZG2A motor:

http://www.mytractorforum.com/attachment.php?attachmentid=240191&d=1355415898

You should at least be able to decipher the part number using the last page.

 

[KentT]

According to what I just learned from a heavy-equipment repairman, when leaking at the shaft seal, it usually means there's a deeper problem inside the motor, such as worn bearings or shaft that let the shaft move around, wearing out an internal high-pressure O-ring type of seal. The shaft seal is more of a "dust seal" not a high-pressure seal. The high internal pressures should be stopped before ever reaching the shaft seal.

IMO, just replacing the shaft seal is a Band-Aid, and likely would not last very long. For a more permanent solution, the motor needs rebuilt, with the shaft and bearings checked for tolerances and wear, and all seals replaced. At least that's what I was told, as I wait for one of my upgraded wheel motors to get totally rebuilt...

 

[ponytug]

What KentT said, x2.

Absent external trauma, e.g. physical intrusion, (stick, nail, etc.), this is great advice.

The bearings, and rotors, keep the axle tightly aligned. So, if you are seeing wear on the outside, there are probably major issues on the inside.

There is not much upside (none?) to delaying a rebuild. If the motor starts shed metal particles, you don't want those circulating to other pumps/motors.

All the best,

Peter

According to what I just learned from a heavy-equipment repairman, when leaking at the shaft seal, it usually means there's a deeper problem inside the motor, such as worn bearings or shaft that let the shaft move around, wearing out an internal high-pressure O-ring type of seal. The shaft seal is more of a "dust seal" not a high-pressure seal. The high internal pressures should be stopped before ever reaching the shaft seal.

IMO, just replacing the shaft seal is a Band-Aid, and likely would not last very long. For a more permanent solution, the motor needs rebuilt, with the shaft and bearings checked for tolerances and wear, and all seals replaced. At least that's what I was told, as I wait for one of my upgraded wheel motors to get totally rebuilt...

 

[/pine]

According to what I just learned from a heavy-equipment repairman, when leaking at the shaft seal, it usually means there's a deeper problem inside the motor, such as worn bearings or shaft that let the shaft move around, wearing out an internal high-pressure O-ring type of seal. The shaft seal is more of a "dust seal" not a high-pressure seal. The high internal pressures should be stopped before ever reaching the shaft seal.

IMO, just replacing the shaft seal is a Band-Aid, and likely would not last very long. For a more permanent solution, the motor needs rebuilt, with the shaft and bearings checked for tolerances and wear, and all seals replaced. At least that's what I was told, as I wait for one of my upgraded wheel motors to get totally rebuilt...

another possibility...
In the same respect whatever the shaft was attached to (externally) could also have been out of alignment/balance etc. and also caused the seal to wear...in a case like this scenario the longer it went unaddressed the bigger the chance that more than just the seal has also worn...

 

[KMA]

Just rebuilt a motor on my PT... it's easy if you can find the rebuild kit for that model. Good luck!

 

[ernemats]

Just rebuilt a motor on my PT... it's easy if you can find the rebuild kit for that model. Good luck!

Just heard back from local hydraulic shop. The motor I have was manufactured before the year 2002 and is no longer made. Am going to take it to the local shop and they will see if they can get a matching seal. Everything looks good and seems tight, it looks like something rubbed the seal .

 

[ernemats]

Just got back from repair shop the motor looks good just needs new seals. Bad news the motor is designed to need a case drain which the case drain outlet had a plug in it. They said it will keep blowing the seal unless it has a return hose put on it. SO I DON'T KNOW WHAT TO DO NOW. How hard would it be to put a return port on to a pt 422 system or would it work on my pt 1845 which has a place to hook up a case drain?

 

[woodlandfarms]

IMO, not knowing your machine, not hard at all. You really need to find a low pressure return line and use it. Lots of them on my PT. Or you could drill a new hole in the tank and just pipe it in.