intermittent hydraulics to front loader

[ScottNC]

DB885 with Dunham-Lehr 22 loader. Twice in the last week hydraulic control of the front loader has quit... temporarily. First time: The tractor had been idling for about 15 minutes after having just used the loader for over an hour. Hopped in the seat and nothing on the loader would move; no up/down/rollback/dump. Shut the engine off, did the work using a shovel instead and half hour later the loader hydraulics worked as soon as the engine was started. Second time: Used the tractor to bush hog for a half hour with the loader raised. Switch to a 3-point carry-all, loaded it and the front bucket with firewood drove to the wood shed, shut off the engine, unloaded the bucket, started the engine, same deal. Had to drag the bucket while turning the tractor around to unload the carry-all. Restarted the engine and viola, the loader worked. Hauled another load and everything worked just fine. Thinking back, I remember floating the bucket and setting the brakes but the tractor rolled toward the shed so then attempted, unsuccessfully to raise the front end slightly with the bucket to hold the tractor. So, at that point the loader hydraulics had already quit but it didn't register with me at the time. Had to use lo-low and reverse and use engine compression to keep it from moving.

When the loader-won't-work issue arises the 3-point still works. There is no noise like the pump is having an issue when loader dosen't work.

I do not know how the tractor hydraulics to the loader control valve work or how the loader control works so am at a loss as to how to diagnose the problem. It is as though the hydraulics to the loader is being dumped internally even though the 3-point still works when the loader doesn't. I have a habit of momentarily using the "float" position on the loader control valve when parking the tractor to unload hydraulic pressure in the hoses/cylinders... I wonder if this might be where the trouble lies?

The loader has what I think is called an open center spool valve? The "camel hump" top has been replaced with a flat steel plate with two hoses that go to the loader control valve. The arrangement requires the hoses to be connected together if the loader has been removed to keep from dead-heading the hydraulic pump.

 

[Adirondack case guy]

Sounds like the feed tube to your pump has a leak or bad restriction, and it is loosing prime.
Loren

 

[ScottNC]

(quoted from post at 10:11:31 11/22/18) Sounds like the feed tube to your pump has a leak or bad restriction, and it is loosing prime.
Loren

Hey Loren. For clarification, are you referring to the tube from the filter to the pump? My hydraulics vacuum light (unwired with no light when I got the tractor) is always on, since everything worked I suspected a bad sender. FWIW the filter and fluid has maybe a tick over 10 hours on them so a restriction there is unlikely. A leak though... Since the 3-point works when the loader doesn't I had figured the inlet side of the pump was okay.

 

[ScottNC]

Bumping this up in the hopes Loren or someone else might clarify if the stamped looking tube from the filter to the pump is the one he thinks has an issue.

Also, if the 3-point still works when the loader doesn't means the pump inlet side is okay... or not.

Been in the deer woods (and working up meat) so haven't had a chance to look at the tractor. Need it (the loader) to discard a gut pile so maybe later today.

 

[ScottNC]

So I go to dispose of my offal pile, the loader works until it is time to dump its contents. Bucket one foot off the ground and none of the loader controls work. To verify to myself the 3-point really does work when the loader doesn't, I pull the quadrant back to the "select" position to release the lock and just like that, as soon as the bypass valve squeals the loader works. What should that nugget of info be telling me?

I'm getting a complex posting to myself...