Deere 710c backhoe hard start issue.

[jenkinsph]

My knowledge of JD ind tractors is very limited but I do understand closed center hyd's. I don't understand the need for a steering charge pump on closed center hyd system. Turning steering wheel back & forth during starting process relieves pressure buildup and to my knowledge was originated by a JD representative not a farmer. What indicates destroker valve is operating correctly? Have you checked voltage to it? How did you check it's operation? It sounds to me that the de-stroking valve is inoperable.

You would think if the tractor operates okay after starting, including power steering and loader/backhoe functions that this belt driven pump is okay.

I am with Jim and would check out the destroking valve as it would be the most likely cause of the problem. The main hydraulic pump is a heavy load on the engine, much more than the belt driven pump. I would hope the de-stroking plunger is the problem as it would be the easiest and cheapest thing to change/fix.

Pull the de=stroke out and check it for operation across the battery with a fused test lead. Then make sure the parts in the main pump are moving and not locked up.

 

[texasranger556]

How does the observation of wiggling the steering wheel to increase starting RPMs fit with a faulty/stuck de-stroking valve? Not being a smart a@@, just trying to understand.

After some quick research of priority valves (but zero experience) it does seem possible for the valve to stick and cause the steering/charge pump to run higher pressure than normal. But I don't know which circuit (steering or main pump) gets "priority" and how that is implemented.

 

[Tx Jim]

texasranger556
I have no experience with the belt driven charge pump nor have a clue what it's purpose is. IMHO the stroke control valve doesn't get stuck but pressure leaks off of hyd system when engine isn't running therefore when attempting to start engine hyd pump is attempting to build pressure & wiggling steering wheel provides an outlet for the building pressure to go.
Jim

 

[mguitas]

90 Deere 710c has had start issue.

Has new batteries, cabling in good shape, new starter. extra ground cables put on. and still starts hard. It starts like the batteries are weak (yes new batteries have been tested).

It will crank better with the farm fix of wiggle the steering wheel so its seems like it's hydraulic related. It seems like the unloader solenoid is working (its on the main pump).

What has us really scratching our heads is there is a power steering pump that is belt driven??

Why would steering wheel jiggle work for starting issue?? I'm confuzzeld or are we overlooking something in the hydraulic system..

Can anyone please explain?? throw me some ideas

I will have to ask my brother about this problem, since he does all the work on the 710c.