Hydraulic pump noise?

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rws

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Joined
Feb 9, 2005
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3
I'm new here. I purchased a 753 with 3900 hours on it. Runs good, but, in cold weather, I loose hydraulic power in both bucket and movement functions. When I try to eitrher move or lift, I heard a rather loud "groan", feels like things are vibrating, as if it tried and couldn't do what I wanted. If I am moving fairly slow, going along fine, and try to increase speed, or turn sharp, I'll get the same groan and power dies. Any ideas? The machine was purchased at a Bobcat dealer, and all filters were changed at the time of sale. Could the hydraulic old be old and thick? Is there a relief valve that could be opening too fast? Thanks in advance.
 

sterlclan

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May 1, 2004
Messages
528
I own a 630 and in the splitter block on the hyd pump in the line that goes to the hyd cooler there was a relief valve just a spring and ball and the spring was junk and it made the same kind of noise but mine was a hot condition.Go to ebay and get the repair manual you will thank yourself later good luck
 

StuZ

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Joined
Nov 22, 2003
Messages
133
No matter what, tighten your main drive belt. How old of a loader is it ?? Serial # ??
 

rws

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Joined
Feb 9, 2005
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3
No matter what, tighten your main drive belt. How old of a loader is it ?? Serial # ??
I'll have to get the serial number and other spacifics tomorrow. I guess a repair manual would be in order. I'll update with the info.
 

rws

New member
Joined
Feb 9, 2005
Messages
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I'll have to get the serial number and other spacifics tomorrow. I guess a repair manual would be in order. I'll update with the info.
Sorry it has taken so long to retrieve this info, had it filed away so well I couldn't find it! It'a a 1995 753, serial number 512711568. Does this offer any help with a diagnosis?
 

HydraulicGuy

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Joined
Mar 21, 2005
Messages
7
Sorry it has taken so long to retrieve this info, had it filed away so well I couldn't find it! It'a a 1995 753, serial number 512711568. Does this offer any help with a diagnosis?
rws, Does the groaning and loss of power only happen when it's cold? Assuming this is so and you have already checked the fluid level, It sounds like you have a problem either on getting fluid into the auxiliary pump or air is getting into the suction line. First I would check the suction hose feeding the auxiliary pump. Make sure it is not kinked or cracked, make sure the clamps are tight. For the $10.00 to $20.00, I would just replace it to make sure it's good. It could be collapsed internally as well. It is a good practice to put (2) clamps on each end and put the clamps 180 deg. from each other. Second, I would check the hydraulic fluid you have in it. If the fluid is to thick, this would cause cavitation when cold as well. I use AW32 hydraulic fluid in my 642B. This brings on the question, "How can you tell if it's to heavy of fluid?" The correct answer would be to send an oil sample in and have it tested but that's not the easiest thing to do. Go to your local farm store and buy a jug of AW32 hydraulic fluid and compare it when both fluids are the same cold temp. This pump not only handles all of the auxiliary functions but also "supercharges" both hydrostatic drives. If the auxiliary pump is "sucking air" or cavitating it would not only cause your bucket functions to fail, but also cause the drives to be irratic. Check those things out and get back to me with your findings. Hope this helps Regards
 
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