Best way to track an aeration issue?

[MikeWNY]

Hey, I've got a Case 1737 skid steer- drive system is mechanical and the tilt/lift is hydraulic.

I've got some sort of aeration issue, or so I think. The machine used to make a high pitched whirring ONLY when the machine was doing work, but not during a fluid dump scenario like dropping the bucket. This was also accompanied by a rock rattling sound coming from the pump- like sand bumping around.

I found the vacuum gauge on the dash was unhooked, so i screwed that back in and the whirring largely went away.
Would it be expected that the vacuum gauge was causing the aeration issue? I would think it would, but I'd like someone else's opinion.
At the same time, I do get the rock rattling sound even now, once in a while, so I think there's still an intermittent issue.

Are there any clever tips/tricks to finding out what the source of this is? I've heard of the squirting oil until it stops thing.
Previous owner was running 303, which I'm gonna replace later this week. Operation is sluggish when the high pitched whirring/rattling occurs but otherwise is fine.


Thanks guys, stay healthy.

 

[Dave M7040]

Your machine has a gasoline engine correct?

If this is true then the vacuum gauge likely has more to do with the engine than the hydraulics.

Pumps struggling to get fluid result in noise and air. Check the suction side of the pump and replace any old rubber hoses.

Dave M7040

 

[MikeWNY]

Got it- there's some old hoses down there. I'll start with that.
Yeah, it's a gas engine but the vacuum gauge is hooked up directly to the hydraulic filter right before the pump- i can see it going in and it's on the schematic I have. I'm struggling to find much online with regards to an optimal value for my gauge. The manual says replace the hydraulic filter when the gauge gets to red but the **** thing is so old and faded there's no more colors on it haha. My intuition leads me to believe a higher vacuum reading means it's harder to draw the fluid through the filter. It's pretty low on the gauge right now.

Do you think the hoses usually leak through the hose itself or more through the fittings? I'll pull them and replace them- hope it works
Thanks

 

[wdchyd]

A trick I use is clean grease. Smear a suspected spot on the suction side with a hefty glob and try it, then wipe it off and move to another spot. It works on fittings, tubing, hoses and shaft seals. If your problem is excessive vacuum then air entrainment is amplified but another issue could be cavitation, (a restriction also on the suction side)

 

[wdchyd]

Don’t overlook the shaft seal on the main pump where it connects to engine.

 

[oldnslo]

If vacuum gauge is on filter in pump inlet then I would change the filter with a known OEM filter element and triple check for leaks on inlet side of the pump. Reason i recommend OEM filter is that some people have had problems using off brands on pump inlets.

 

[MikeWNY]

Just ordered some new hoses, clamps, and filters. I'll try the grease trick out and tighten the pump housing to the gearbox- hopefully I don't have to take it apart.
Thank you kindly!