Branson 3520h - Hydraulic level confusion

[pockman]

Hi all,

I have a Branson 3520 hydrostat with about 100 hours. It sat a couple of seasons so I am going through checking, topping, etc. I noticed the hydraulic/tranny fluid in the rear sight glass was low (below the 1/3 mark) while parked on an incline. After I moved the tractor to level ground, I couldn't see any fluid in the sight glass. No problem - grabbed a 2 gallon jug of premium from TSC.

I started by adding some, checking the glass, little more, check the glass - no fluid. By the time I poured somewhere around half to one gallon (10 gallon capacity), the fluid was sitting at the top of the fill port. Confused, I removed the funnel and everything I added proceeded to up and drain out of the fill valve. Then the color changed - presumably the original fluid - and that was draining. I stuck the cap on and cleaned everything up. What a mess.

Then I started the tractor, moved the bucket up and down, fiddled with the backhoe just to move the fluid around. I noticed that more fluid had pushed through the hydraulic fluid fill cap (shaped like a cane).

I am sure I did something wrong but am very confused. My best guess is an air bubble but I don't know what I should have done differently or how to address. I assume with an unknown amount of fluid, driving this (let alone working it) is a huge risk at least to the transmission.

Appreciate any insight.

-pockman

 

[workinonit]

I would drain all of that fluid out and start over.

 

[Blue14]

After you pulled your tractor back on level ground did you wait about 5 minutes or so for fluid to drain down and stabilize before adding more fluid? I also assume you shut the tractor down first?

 

[oosik]

Dam - don't you just LOVE those sight glass's for fill check. What workinonit says - about your safest choice.

THEN when everything is back filled and at the correct level - make you own dipstick. Simple chunk of rod or a metal coat hanger. A mark at the oil full level - a mark at where to hold it at the fill port.

 

[pockman]

Thanks all.


Yes, I waited a few minutes before adding fluid.

Do I need to replace the filter as well (since it'll hold some fluid)?

That seems crazy, can anyone think of a rationale for this? Seems like topping off fluids should a no brainer.

 

[Xfaxman]

All the hydraulic cylinders need to be retracted before checking or adding fluid.

If the loader was up or bucket dumped some, the level will be low because the of fluid that went to the cylinders.

 

[pockman]

Good grief. I had the outriggers on the backhoe up and the backhoe bucket curled. Seems so obvious.

I assume i should have lowered everything, shut off the tractor and played the levers to get everything to relax. Similar to prepping to disconnect backhoe.

Is there any salvaging the fluid if i relax everything? Or should I drain everything and refill? Assuming the latter, how much fluid should i do vsm listed capacity, and what should be deducted for filter? Or can i theoretically trust the glass?

 

[ericm979]

The oil tank is the transmission housing... which is long and narrow. The sight glass is at the back. So the level on the glass can vary a lot with a small change in incline.

If your oil is clear it's hard to tell the difference between no oil showing in the sight glass and oil covering it. You're not the first person who has mistaken overfull for too low and added even more.

When I change the oil in my 3725 (very similar to a 3520) I fill it slowly, on a level surface and with the cylinders retracted, and watch for the level coming up in the sight glass.

 

[pockman]

For fun I went out and moved all the levers around and that relaxed everything. Unscrewed the hyd cap and it immediately started leaking out. Nothing showing in sight glass. I cannot imagine this is overfilled...?

 

[pockman]

Ericm979,

I see what you are saying but when i was on an incline (front up, back down), i could see the oil level appeared low. On level ground I would have expected to see it around 1/3 to 1/2 at most.

-pockman