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Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 5300
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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Have an older Bobcat 643 Skidsteer, had to have some engine

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Have an older Bobcat 643 Skidsteer, had to have some engine repairs done after which everything was working fine. Then a problem with turning left and right, would move forward and backwards but wouldn't turn. Now have lost any motion altogether, forward, backwards, left or right. However, when first starting up,for about the first five minutes, everything seems normal, then you lose turning cabability and then motion altogether. Pump does scream a bit, but it always has. Everything has been checked, center plate bushings /adjustments, fluid level, etc. Bucket and lifting arms working as they should. Any ideas?

Hi, Its Dan, I replied to your last post to begin helping you with this. What is the serial number of you machine so I can be sure to get you the correct information?

Customer: replied 1 year ago.
Bobcat 643 Skidsteer. #D 1402
SN# *****

Thanks for the info. What did you have done for engine repairs? I would verify the pump drive coupling is not slipping or has failed. If ok then check the safety interlock circuit if you are loosing all functions or being locked out all at once. If ok check the hydraulic filter for signs of fine metal/debris in the filter and oil indicating a pump or component failure occurring. Let me know

Customer: replied 1 year ago.
First five minutes of operation everything is fine, then you lose turning cabability and then all drive motion. This is an older, older model so alot of the electronic lock outs don't exist. Engine work : had blown head gasket and cracked head, injectors, glow plugs,oil, air filters. Do to the screaming of the hydraulic pump, I may start with draining hydraulic oil and checking filters for shiny debris.

Thanks for the update.... I would definitely start there. Cut the filter open with a non abrasive tool or filter cutting tool/ exhaust cutting tool to prevent contaminating the sample with cutting filings.... Cut out a good sized section of the filter media and squeeze out the excess oil in a vice, then inspect in the light for metal. Will look like glitter in the oil or filter.

Customer: replied 1 year ago.
This is one of those ..... everybody and their brother has done their part before I received the project, I'm sure you know how that is. I'm thinking the drive pump is not the same pump that operates the bucket. First thing in the morning I'll need to obtain a manual for this unit.

Click this link. PDF manual for under 10 dollars for instant download.


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