Chinese backhoe hydraulic pressure issue

dfkrug · Aug 31, 2016

BRETTSKI:

I assume you have verified clean fluid as suggested above. It is also important to make sure the inlet to
the pump is not obstructed, causing cavitation. Sometimes these PTO pump systems use an inlet
screen inside the tank on the inlet of the IN hose. You should also make sure the vent in the cap is
not blocked and the fluid is not contaminated.

I am certain you have a trochoid (gear) pump that looks something like this photo. If it is Chinese,
it also may have poor assembly and internal leaks due to improper seal installation.

brettski · Aug 31, 2016

For all my ****-retentive attention to detail, I often resolve my most perplexing challenges by rectifying a simple, stupid error. These errors are normally self-inflicted. I keep hoping that this will be the same deal. It will be something stupid simple. This is a common occurrence with the king of overkill.
I have a number of great suggestions from all of you. I am grateful. I will be at the farm this weekend and will be pursuing many of these various suggestions. I will report back.
I continue to check this thread for the experienced input. Please keep 'em comin'. It makes a difference; thank you.

wdchyd · Sep 1, 2016

A flow/load test meter is what you need to rule out pump problems/wear before you go any further......you may be chasing your tail not knowing if the pump is good or bad......call around to a local tractor or hydraulic shop to see if they have one to hook up to your tractor

wdchyd · Sep 1, 2016

http://www.tractorbynet.com/forums/2052443-post33.html

CJONE · Sep 2, 2016

Sounds familiar!! WD. How long have you been doing hydraulics? Roughly 30 years for me. Been doing a lot of hydrostatics in the last 15 years. CJ

CCWKen · Sep 2, 2016

Many professionals here must remember that not many folks have a set of pressure-flow gauges or pump test stands laying around for occasional use. "In the field" type diagnostics work best. Lending your expertise and experience on common faults will go further than pointing someone to a catalog of test equipment. Once the problem area(s) is/are identified then it's up to the owner to decide if further testing is worth the expense. Personally, I was surprised the OP had a hydraulic pressure gauge. Perhaps he needs help on where to locate the gauge and how to use a valve to get a proper reading without a flow gauge instead of hearing all the back slapping and about all your years of experience.

wdchyd · Sep 4, 2016

CCWKen said:
Many professionals here must remember that not many folks have a set of pressure-flow gauges or pump test stands laying around for occasional use. "In the field" type diagnostics work best. Lending your expertise and experience on common faults will go further than pointing someone to a catalog of test equipment. Once the problem area(s) is/are identified then it's up to the owner to decide if further testing is worth the expense. Personally, I was surprised the OP had a hydraulic pressure gauge. Perhaps he needs help on where to locate the gauge and how to use a valve to get a proper reading without a flow gauge instead of hearing all the back slapping and about all your years of experience.

Really???
Is that what we are doing.......backslapping??

wdchyd · Sep 4, 2016

BTW, CJ.......since July 1976
(Slapped ya back)

brettski · Sep 6, 2016

Well, not a lot progress in testing this past weekend. The backhoe is disconnected and in storage in the garage and I had no time to hook it back up for any operative testing. I did make double sure there was plenty of oil in the tank. Yep; it's about 80% full. By measurements (and 7.48 gal per cu ft), the entire tank holds 5 gallons. The Chinese factory wanted evidence that the hoses I tested were not damaged or crushed or whatever. They aren't and I forwarded pictorial evidence.
I think my next step is to check for a screen on the pump intake hose at the tank. Kinda hard to believe since it is a hose fitting welded to the tank with a hyd hose connected to it. Not sure how a screen would be incorporated into that. What about the chances that the spin-on filter is gumming up the flow? It's all (supposed to be) brand new.

CJONE · Sep 7, 2016

brettski said:
Well, not a lot progress in testing this past weekend. The backhoe is disconnected and in storage in the garage and I had no time to hook it back up for any operative testing. I did make double sure there was plenty of oil in the tank. Yep; it's about 80% full. By measurements (and 7.48 gal per cu ft), the entire tank holds 5 gallons. The Chinese factory wanted evidence that the hoses I tested were not damaged or crushed or whatever. They aren't and I forwarded pictorial evidence.
I think my next step is to check for a screen on the pump intake hose at the tank. Kinda hard to believe since it is a hose fitting welded to the tank with a hyd hose connected to it. Not sure how a screen would be incorporated into that. What about the chances that the spin-on filter is gumming up the flow? It's all (supposed to be) brand new.

0 If it is on the return side. Suction issues cause surging and pumps to cavitate and destroy themselves. To have a steady 1300psi you either have a pooly assembled pump or a relief issue like has been posted. CJ