M936A2 Wrecker crane noise

[Swope]

This is my new wrecker. I have used the crane before a couple of times with no problems. Today I was extending and retracting my boom and lowering and raising the hoist under no load when the crane started to make a louder winding/screeching noise. At that point if started to operate much faster and I thought, "Oh Good" until I saw hydraulic fluid pouring out of the reservoir cap. Any ideas what the problem is?

 

[NDT]

I think air entrainment. This happens when a seal or hose allows air into the system, and the volume of fluid expands because it is full of microscopic bubbles.

 

[simp5782]

What rpm were you running at?

 

[Swope]

What rpm were you running at?

1600-1700

 

[Swope]

1600-1700

Today I put the boom and hoist through its paces doing exactly what I did yesterday and it did not repeat the problem. No noise and no fluid shooting out the cap. Do you think it was a stuck valve or possibly a seal going bad? Should I just ignore it for now or is it an indication of a serious problem and I should take something apart?

 

[Swope]

1600-1700

Today I put the boom and hoist through its paces doing exactly what I did yesterday and it did not repeat the problem. No noise and no fluid shooting out the cap. Do you think it was a stuck valve or possibly a seal going bad? Should I just ignore it for now or is it an indication of a serious problem and I should take something apart?

 

[The FLU farm]

The front hydraulics on one of my Unimogs does that every now and then.

Best I can tell, it's usually when it's been cold out (around zero or so) and when I'm a bit too quick with raising the loader and start driving.
And the fluid coming out is aerated big time.