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Hydraulic charge pressure warning light
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I am new to this site and have a question regarding the hydraulic charge warning light on a 1993New Holland 785 loader that I have purchased used.
Recently the charge press. warning lite has been coming on and stays on . I have cleaned the suction strain filter and replaced the return line filter and charge inlet filter. This seems to have helped as the lite now takes about 15 minutes before it comes on after starting the machine. I did notice metal particles( very fine ) on the suction screen magnet. This is far as I have gone . Do I need to be concerned about the particles or is this normal wear? The machine has about 3000/3500 hrs. on it. When I changed the filters I noticed a milky(?) appearance of the oil compared to the fresh oil . Any suggestions as to where to go from here ?
Any help would be appreciated.
Posts: 1 | Registered: 13 November 2006Reply With QuoteReport This Post
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It sounds like this unit has a closed loop hydrostatic transmission for propulsion. I would recommend removing the pump and motor promptly for service. A drop in charge pressure as the machine warms up is a sign of growing internal leakage. Hesitation could result in damage beyond economical repair to the transmission.

"There are only 10 kinds of people in the world --
Those who understand binary, and those who don't."

Posts: 146 | Location: Dallas, GA | Registered: 19 September 2006Reply With QuoteReport This Post
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That milky color indicates water in the oil and needs to be completely cleared before you have real problems.

The reduced pressure after warm up indicates the oil has been stripped of all its additives due to overheating and thins out quickly so it is bypassing every clearance at constantly reduced pressure. The system will not get better on its own no matter how many filters you change.

If it were my machine and I planned on keeping it for any time at all I would drain all the oil, and that may mean pulling lines or draining all that is easy , refilling, operating the circuit until it warms up and repeating the process until the oil comes out clean and clear.

$200.00 worth of oil is a lot cheaper than a $3,000.00 pump and a $2,000.00 motor and the cost of installation.

If the oil gets milky looking again I would be trying to find out if the oil is cooled by an oil cooler immersed in the engine cooling system that is leaking and filling the hydraulics with water.

If it belonged to me.

Bud Trinkel
FP Consultant Retired
"It is incumbent on every generation to pay its own debts as it goes. A principle which if acted on would save one-half the wars of the world. "Thomas Jefferson"
Posts: 1761 | Location: Newburgh, Indiana | Registered: 07 October 2005Reply With QuoteReport This Post
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