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843 drive problem

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phmteck

New Member
Joined
May 15, 2013
Messages
2
Location
indiana
hi all,

first post here.
I have a early year 843 bobcat. i have drive problems that happened all at once. I have no forward or reverse on right side and very erratic drive on left side. to me it seems like hydraulic drive pumps are not getting enough oil. I installed a gauge into the charge line and i have 200 psi going into #9 port block. but when i put a gauge into the outlet "T" that goes to the drive pumps there is no pressure.
i pulled the relief valve in the port block #8 but saw nothing wrong with it.
Can the high pressure replenishing valves #4 be the culprit? not sure what exactly they do in the hydraulic pumps. Do they control the charge pressure going to each pump? If i hold the drive lever in one direction it will jerk forward and then quit like it has no more oil.
I am stumped? I'm a mechanic by trade so I can do the work. Just trying not to have to take a trip to the Stealership.

Thanks in advance

Dan
843 hydraulics.jpg
 
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Part sman

Well-Known Member
Joined
Feb 25, 2010
Messages
45
Location
usa
Check the filter- under the fitting- at the #9 location for blockage. This will cause an issue with charge pressure to the pumps. Pull it out an try to blow thru it. You can also remove it completely and reinstall the fitting- for testing purposes.
 
P

phmteck

New Member
Joined
May 15, 2013
Messages
2
Location
indiana
Part sman said:
Check the filter- under the fitting- at the #9 location for blockage. This will cause an issue with charge pressure to the pumps. Pull it out an try to blow thru it. You can also remove it completely and reinstall the fitting- for testing purposes.
Click to expand...

Ok! I've pulled the 40 micron filter and inspected before and even thought it was clean. Thinking is always my downfall! Anyway I pulled filter again looking at it still looked clean,but I sprayed parts cleaner and shop air threw it and was amazed at the amount of crap that was trapped in the thing.
I cleaned for at least 10 minutes and reinstalled.

Woohoo! The 843 lives to work again. I guess I'll have to go pick up a new bronze filter for the beast. Amazing something so simple can be such a pain in the a**.
Next time I'll start with the easy stuff and go from there.

Sorry to waste anyone's time, but Thanks a million.

Dan
 
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