2002 Bobcat 334 Min Excavator - Right Side Track Doesn't Turn

[Halman3985]

Hey Everyone,

Please forgive my lack of knowledge when it comes to excavators. I own a 130 acre farm with 30 acres of bush and a lot of ditches. Last year, I got a good deal on a Bobcat 334. The excavator worked great and started like a champ any time I used it which wasn't very much. A couple of days ago, I took it out of the barn to use it since we had some fallen trees and needed it to move the big limbs. Anyways, as luck would have it, the right side track will not turn on its own. The left side turns without any issues at all. I removed the bottom plates (below the operator seat) to see what is going on or if a cable disconnected but it all looks well. Anyways, from everything I've read to this point, I think it's the final drive system on the right side of the excavator. However, before I go and take anything apart, does anyone have any other suggestions? The fluid level is fine, it was a little bit low and I topped it up but it didn't require much. All my gauges seem to be working and i know the sprocket isn't seized since I lifted the right side and was somewhat able to slightly move the track and when I do move the excavator using the left side, the track does turn just not using the lever. So, am I on the right track (no pun intended), is it the final drive system?

Cheers,

Shawn

 

[laurencen]

had a 430 some years ago, it had issues weak left track drive, traded it off and was told one of the pumps was bad, when you try to move the track any sound the pressure is getting to it? is it a single pump machine?

 

[mwayne]

If it turns out you need to replace the drive motor this video might be useful.

Replacing excavator final drive hydraulic lines - YouTube


This is for a skid steer but might also be useful.

Installing a drive motor in a tracked skid steer - YouTube

 

[Seven Gables]

If you have access to some hyd pressure gauges the first thing I would do is disconnect the drive supply hoses at the motor and see what you've got , should be around 3000psi . If that is way low its likely not the motor. How many hours on the machine? Could be the seals in your hyd rotary Union or the control valve for that motor is not getting stroked. Does that year machine use pilot hydraulics to operate control valves?

 

[SSdoxie]

First diagnostic step is determine if hydraulic flow/pressure is getting to the motor. Using a gauge is proper way however if you remove one of the larger hoses at the travel motor valve block and cap the fitting and plug end of the hose with steel plug and cap (Hose fitting is JIC flare either #8 or #10) then start engine and stroke travel lever each direction and listen to engine. If engine lugs then problem is at the motor.

With motor access cover removed look for signs of oil leakage. One of the failure that can cause loss of drive is cracked relief valve housing or bolts holding it to motor stretch and Orings leaking.
If no signs of leakage and end lugs with hose and motor fitting lugged, remove the drain/fill plug at the outer end housing to check condition of final drive (gear reduction) of the motor.

 

[Halman3985]

Thank you everyone for your responses. Still not exactly sure what the issue is but I did do this today. I removed the cover for the final drive of both the working and non-working track. Both were found bone dry as far as any oil leakage is concerned. But, I removed the top plugs for both sides, I found that the working track had nice clear oil which wanted to come out as I removed the plug but the track that doesn't work had dirty oil and the oil didn't come out whatsoever. There is another plug behind the first one and when I removed it the oil did start coming out and it appeared clear (track which doesn't tur). Anyways, the Bobcat has 4300 hours on it, probably 15 hours of which are mine.

 

[Seven Gables]

Just for some more clues did you check the final drive level and condition as was suggested? Also check the case drain filter to see if it's dirty and plugged up?

 

[fried1765]

Hey Everyone,

Please forgive my lack of knowledge when it comes to excavators. I own a 130 acre farm with 30 acres of bush and a lot of ditches. Last year, I got a good deal on a Bobcat 334. The excavator worked great and started like a champ any time I used it which wasn't very much. A couple of days ago, I took it out of the barn to use it since we had some fallen trees and needed it to move the big limbs. Anyways, as luck would have it, the right side track will not turn on its own. The left side turns without any issues at all. I removed the bottom plates (below the operator seat) to see what is going on or if a cable disconnected but it all looks well. Anyways, from everything I've read to this point, I think it's the final drive system on the right side of the excavator. However, before I go and take anything apart, does anyone have any other suggestions? The fluid level is fine, it was a little bit low and I topped it up but it didn't require much. All my gauges seem to be working and i know the sprocket isn't seized since I lifted the right side and was somewhat able to slightly move the track and when I do move the excavator using the left side, the track does turn just not using the lever. So, am I on the right track (no pun intended), is it the final drive system?

Cheers,

Shawn

Please add your general location to your profile.
It will often help us to help you.

 

[Halman3985]

Going to check that today. For the final drive level, is this what you are referring to. Please see image.

 

[Peter 315]

Going to check that today. For the final drive level, is this what you are referring to. Please see image.

View attachment 650614

Ya that's the final drive you check level should be marked on it...

 

[Halman3985]

I checked the level, it was a tad low and I added a little bit of oil but it didn’t make any difference. I thought I would be adding a lot but that wasn’t the case. Don’t know what else to do at this point. Everything on the machine works great except for the right track which doesn’t turn at all.

 

[Seven Gables]

At this point I would take SSdoxies advice to cap and plug one of the two in out supply lines then operate your control lever to that motor. If the engine bogs down and you hear the relief valve open and squeal odds are you've got good flow and pressure to the motor indicating that your drive motor is at fault. The other thing that you absolutely should do and is easy is pull the case drain filter and see what you find. I think it's located under the right side shroud but not sure, it's a small sintered bronze filter inside a small canister maybe 11/2" in diameter. Very important to replace this filter anyway. There is engineered leakage from your drive motors that flow through this filter on way back to supply tank , if it plugs up it can destroy your drive motors/final drives. Let us know. B

 

[Seven Gables]

It appears that your case drain filter is not a sintered bronze filter , it is a spin on #6516722 if what I found on line is correct. B

 

[Halman3985]

Thanks for all the help everyone. It was indeed the final drive that was faulty. Just ordered a replacement, not cheap at all....

 

[SSdoxie]

Thanks for all the help everyone. It was indeed the final drive that was faulty. Just ordered a replacement, not cheap at all....

Was it on hydraulic drive side or the gear reduction side?

 

[Halman3985]

Was it on hydraulic drive side or the gear reduction side?

It was the hydraulic side. Hey, if anyone in Ontario Canada has a similar issue, try buying the part from Equipment Parts Depot, North Toronto. The drive was approximately $2000 cheaper than buying it from Bobcat. The drive itself was made in South Korea and seems very well manufactured. When connected, the drive angled down slightly which made it a little bit of a pain to connect the hydraulic hoses but other than that, all went very well.