JCB 801 No Hydraulics

[John W]

Hi all.
I have an old JCB 801 with what appears to be no hydraulics. Its a floor lever model, not the later joystick type, if it makes any difference.
Despite being an old machine and having a few weepy seals on the rams it has been working ok when needed.
Last week it was working as normal and then it was as if it lost all pressure. No response to any controls.

The engine runs fine, and I have checked the fluid in the filter tank. It is pretty fresh fluid too.
It has a 3 stage pump, but can't really see it being all 3 stages failing together.
I assume even if I tried to check the pressure output of each stage it is going to be misleading if something is not allowing it to build pressure.

I don't think it is a hose failure (checked all the visible ones) or I would expect to see fluid everywhere, which there isnt.
Do these machines have a single pressure relief valve or something that could be stuck ?
Or could it be something blocking the feed to the pump ?

The electrics arent very complex but are there any control valves or fuses I should be looking at ?

I'm a bit stumped at present, as it it likely something quite simple, just not sure where to check.

Cheers all,
John.

[John W]

Further investigation.
I swung the tank out the way, and all hoses look fine.
I took the top off the oil filter / oil tank. no oil being returned.
undid one of the output hoses at the pump. No output from the pump.
Trying to remove one of the inlet hoses proved a nightmare, so I removed the end plate of the pump block. This resulted in lots of oil running out, so seems oil is getting to the pump. Cranked the engine and I see both shafts rotating.

So do I have a screwed pump ?
Seems odd that all 3 sections would fail together.

How is the pump coupled to the engine ?
I'm wondering if it doesnt pump when under load or something.

Can i simply unbolt the pump from the bellhousing, or is it more involved to remove the pump from the engine ?

Any pointers gratefully received.

Regards,
John.