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Leaking final drive

kneelo

Active Member
Joined
Aug 21, 2009
Messages
30
Location
Bunbury, Western Australia
I noticed some oil leaking from the cone seal on on one of my final drives so i checked the oil level and its full (to the brim not just the fill plug) and seems to be under very slight pressure. I'm guessing the shaft seal on the motor has gone filling the gearbox with hydraulic oil and that the case drain has enough pressure to make the cone seal leak.

I had a look at the parts manual and it looks like changing the motor shaft seal is simply a matter of unbolting the motor from the gearbox, slipping it out then replacing the seal which is retained by a circlip. Am I missing anything?

By the way the machines a Hitachi Ex270-5.
 

Cat Wrench

Well-Known Member
Joined
Mar 27, 2010
Messages
121
Location
Missouri
This is most likely a sign that the drive motor has excessive leakage and needs to be repaired/replaced. You could try a seal and see but the odds are you will have to address a drive motor problem soon. How many hours are on the machine?
 

kneelo

Active Member
Joined
Aug 21, 2009
Messages
30
Location
Bunbury, Western Australia
It's got 12000 hours so a tired motor wouldn't be a suprise.

Would the way to check the motor condition be with a pressure gauge on the case or case drain line near the motor?
 

KenAl

Well-Known Member
Joined
Mar 30, 2007
Messages
194
Location
north
A common thing on EX270-5. The motor shaft bearing races wear into the case and allows the shaft to move outwardly slowly allowing case drain oil into the gear case. I have changed the case and reused the rest with great results. But not with 12000 hrs on the components. I also reset the bearing rolling torque. Keep in mind the other side if not leaking is most likely soon to have the same symptoms. This usually is not enough pressure (case drain pressure) to blow the duo-cone. Once again 12000 hrs those seals are worn too.
Doing a case drain test on the motor would be the best way to tell what condition it is in. At 12000 hrs they most likely have been changed. Unless you are the original owner.
 

Cat Wrench

Well-Known Member
Joined
Mar 27, 2010
Messages
121
Location
Missouri
I agree with KenAl. I would check the case drain and if it shows excessive leakage I would pull both drive motors off and have them repaired. It would be a good idea to reseal the rotary manifold as well.
 

ddigger

Senior Member
Joined
Jan 19, 2009
Messages
567
Location
Northern California
Occupation
contractor,owner operater
I just finished that little chore on my 330l, l caught it before it blew the seals in the final. On mine that shaft seal cannot just be replaced, its the first seal to go in, an the last to come out. I have yet to reseal the rotary manifold on my cat, I have done it on a 792 deere I used to own, about the same I would figure.
 

John C.

Senior Member
Joined
Jun 11, 2007
Messages
12,865
Location
Northwest
Occupation
Machinery & Equipment Appraiser
To check the case drain you should open the cap on the hydraulic tank and drain all the pressure off. Take the drain hose off the motor and cap it. Put a short hose on the motor drain and put it in a bucket. Block the track with a pin or the bucket and run the motor over relief. If the motor is shot the hose will probably try to leave the bucket in a hurry. If you just get a dribble you are probably OK.

Keep in mind the seal could still be bad and the case drain not be excessive.

Good Luck!
 

Little Z

New Member
Joined
Jul 3, 2020
Messages
1
Location
Hammond La
To check the case drain you should open the cap on the hydraulic tank and drain all the pressure off. Take the drain hose off the motor and cap it. Put a short hose on the motor drain and put it in a bucket. Block the track with a pin or the bucket and run the motor over relief. If the motor is shot the hose will probably try to leave the bucket in a hurry. If you just get a dribble you are probably OK.

Keep in mind the seal could still be bad and the case drain not be excessive.

Good Luck!
To check the case drain you should open the cap on the hydraulic tank and drain all the pressure off. Take the drain hose off the motor and cap it. Put a short hose on the motor drain and put it in a bucket. Block the track with a pin or the bucket and run the motor over relief. If the motor is shot the hose will probably try to leave the bucket in a hurry. If you just get a dribble you are probably OK.

Keep in mind the seal could still be bad and the case drain not be excessive.

Good Luck!
John do you have any experience with cat 330L drive motors. Little Z in Louisiana
 

John C.

Senior Member
Joined
Jun 11, 2007
Messages
12,865
Location
Northwest
Occupation
Machinery & Equipment Appraiser
I've not had to work on those. They should act the same as any hydraulic motor.
 
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