Hydraulic system drawing air. Can i find where?

foxy farmer

MF 50HX digger gone dog slow and jerky when operating loader or backactor. Pump very noisy and oil gone milky. Got so bad tonight that it couldn't cut a grab of silage and lifting the loader could take 30 secs.
Took out filter and watched oil flow in filter housing with engine running. Oil gets bubbly when working the levers. Revving makes it worse. Have replaced pump with a spare that I got reconditioned a few years back so confident that pump not at fault. New filter and oil recently too.
Any tricks to finding where air is gettting in or is it just a case of checking the pipework bit by bit?

Car99

foxy farmer wrote: »

MF 50HX digger gone dog slow and jerky when operating loader or backactor. Pump very noisy and oil gone milky. Got so bad tonight that it couldn't cut a grab of silage and lifting the loader could take 30 secs.
Took out filter and watched oil flow in filter housing with engine running. Oil gets bubbly when working the levers. Revving makes it worse. Have replaced pump with a spare that I got reconditioned a few years back so confident that pump not at fault. New filter and oil recently too.
Any tricks to finding where air is gettting in or is it just a case of checking the pipework bit by bit?

Air getting in should mean fluid getting out if it was just the pipework .

foxy farmer

Car99 wrote: »

Air getting in should mean fluid getting out if it was just the pipework .

No visible oil leaks. Does air only get sucked in on return line or can it be sucked on high pressure side on way to the valve chests? Have found one worn pipe with braiding showing. Its the main feed from the pump to the loader valve.
My own thinking is the high pressure would force oil out not pull air in.

zfml

Had problems with a very slow hydraulic cylinder on a MF digger. It turned out a piece of rubber was stuck in one of the hoses (the hose collapsed on the inside) just after it left the valve chest. Take off the hose(s) and check there are no blockages.

tomwaterford

Flow test it (even though it's a recon pump)

Or....if you could put the oil recirculating as il not lie....I've never heard of anyone taking off oil filter to check flow

(Don't hugely know these either tbh)....get it warm and keep trying

Nekarsulm

Has to be between the oil resevoir (loader frame) and the suction side of the pump. A new pipe should solve it.
As previous poster said, pipe could be de-laminating, allowing air to be drawn in, or collapsing internally, causing cavitation.
What state is your filter in? Some diggers wouldn't see a new filter in a decade......

foxy farmer

There's one piece of old rubber pipe to be replaced. 2pieces of steel and 2 rubber between tank and pump. Replaced about a ft of rubber within last month. Got new filter and new oil at the same time. New o ring on pump inlet pipe flange yesterday. Took out filter housing tonight and did a rough pressure test in water but it showed nothing. Replacing 2 o rings on tank/ filter housing feedpipe in the morning. Look ok but will replace just to be sure. Going back to MP Crowley MF dealers to see if there's anything else that I could have missed.

Nekarsulm

Crowley should know exactly what the problem is. Other than that, what kind of clips are you using on the suction pipework? Single jubilee clips not sufficient, you would need two at each joining, or the heavy type that tightens with a 13mm spanner, usually found on vacumn tankers

9935452

foxy farmer wrote: »

MF 50HX digger gone dog slow and jerky when operating loader or backactor. Pump very noisy and oil gone milky. Got so bad tonight that it couldn't cut a grab of silage and lifting the loader could take 30 secs.
Took out filter and watched oil flow in filter housing with engine running. Oil gets bubbly when working the levers. Revving makes it worse. Have replaced pump with a spare that I got reconditioned a few years back so confident that pump not at fault. New filter and oil recently too.
Any tricks to finding where air is gettting in or is it just a case of checking the pipework bit by bit?

The same thing happened with my HX a few years back
How did you change the oil? how much oil did it take , 17 gallons??
Did you just drain the resevoir or did you start with the loader in the air and the back actor in the air, drain the resevoir and drop all the rams one by one to empty them all.
Milky oil means there is water in the oil. Paper filters hate water and will go to mush with water present. Did you also clean the mesh filter inside the paper filter. This will block up with paper from the filter.

When i drained the HX at home properly , changed the filter and cleaned the mesh, the hydraulics went crazy fast.
When the filters are blocked it will draw air from anywhere it can. Tightening jubilee clips didnt help me .
I actually know lads who run their diggers with no filters and find them way faster than with.
You might end up having to change the oil a couple of times as its nearly impossible to get the full 17 gallons out and all you are doing is diluling it .
Hope that helps

foxy farmer

9935452 wrote: »

The same thing happened with my HX a few years back
How did you change the oil? how much oil did it take , 17 gallons??
Did you just drain the resevoir or did you start with the loader in the air and the back actor in the air, drain the resevoir and drop all the rams one by one to empty them all.
Milky oil means there is water in the oil. Paper filters hate water and will go to mush with water present. Did you also clean the mesh filter inside the paper filter. This will block up with paper from the filter.

When i drained the HX at home properly , changed the filter and cleaned the mesh, the hydraulics went crazy fast.
When the filters are blocked it will draw air from anywhere it can. Tightening jubilee clips didnt help me .
I actually know lads who run their diggers with no filters and find them way faster than with.
You might end up having to change the oil a couple of times as its nearly impossible to get the full 17 gallons out and all you are doing is diluling it .
Hope that helps

She'll get no new oil till this is sorted.

9935452

foxy farmer wrote: »

She'll get no new oil till this is sorted.

The problem is the oil change is part of the fix
How much oil did you get out of it when you changed it?

Try running it without the filter and mesh screen inside the filter and see if there is any difference.

Nekarsulm

foxy farmer wrote: »

She'll get no new oil till this is sorted.

Like Neil Toibin's "Blue Van"

"Would she burn oil"?
"She would if she got it" !

zfml

@foxy farmer: Did you find out what was wrong?

foxy farmer

Originally air got in through a perished rubber suction pipe. Replaced pipe. Oil had gradually gone to crap. New filter didn't cure problem. Took out paper filter and she worked away but still a bit jittery. Cavitation due to low oil flow to the pump. Gave 2 days getting all old oil out and refilling system. Working grand now. Have the old pump with damaged seals but new seal kit costs nearly as much as new pump. €900

John J. Lyons

foxy farmer wrote: »

Originally air got in through a perished rubber suction pipe. Replaced pipe. Oil had gradually gone to crap. New filter didn't cure problem. Took out paper filter and she worked away but still a bit jittery. Cavitation due to low oil flow to the pump. Gave 2 days getting all old oil out and refilling system. Working grand now. Have the old pump with damaged seals but new seal kit costs nearly as much as new pump. €900

I have a perfect pump off a 50HX if you're stuck

foxy farmer

John J. Lyons wrote: »

I have a perfect pump off a 50HX if you're stuck

Got a secondhand one off a local breaker here and going fine. Thanks anyway. You sorted me out with something before and going grand since.