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Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4291
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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We have a 1998 John Deere 850c Bulldozer and it has quit pulling.

Customer Question

We have a 1998 John Deere 850c Bulldozer and it has quit pulling. We changed oil and filter in it. It will pull for about 15 minutes and gets hot and quits. Mechanics tell me I need to replace both pumps and motors. My theory is that it has to be some sort of valve sticking because both pumps and both motors going out at the same time is unlikely. Any ideas?
Submitted: 5 months ago.
Category: Construction and Road Equipment
Expert:  Dan replied 5 months ago.
Hi Richard, my name is***** will be glad to help. The information they gave can be true but I would not go there without confirmation. Its a very expensive guess. If you have fine metal that looks like metallic glitter in your filter and oil in the hydrostatic system then yes the complete system is contaminated and needs to be completely flushed and the faulty component isolated and replaced. If there is a lot of metal the damage is so that everything needs to be rebuilt or replaced due to contamination. No rebuilder is going to honor warranty of a new pump installed on a contaminated and improperly flushed system.
Expert:  Dan replied 5 months ago.
now if inside the filter is clean and there is nor metallic glitter, etc then you could have a control valve problem or a relief sticking and dumping off the pressure, Most commonly this ends up being a pump failure effected by temperature. Let me know

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