Hydraulic oil foaming out vent hole

[Work Horse]

Hey all,

In need of some help.. again. Yesterday I finished up a front crank seal and hydraulic pump seal on my B7200HST. When I went to test the hydraulics (FEL) everything worked fine except it seemed a bit slow at first. Then I realized foamy hydraulic oil was quickly overflowing from the vent hole. It didn't do this before I serviced the pump. The pump didn't leak at all until right after I shut the engine off, only did it once and now it appears it isn't leaking.. high pressure maybe?

Is it just air? If so how would I bleed it out?

Also is there a good way to check the suction side of the hydraulic system? I assume you can't just spray connections with soapy water.

Also could a small amount of water contamination cause my symptoms? I had the Hydro oil cooler off when I started to hose down the engine, quickly realized it was off - can't imagine a lot could have gotten into the line.

 

[fj40dave]

First thought would be overfilled....but, I'm a hydraulic novice.....and the foaming is possibly just trapped air working it's way out.....

Following to increase my knowledge base in this topic.....

 

[Dave_eng]

Did you replace the O rings on the banjo bolt attaching the suction line to the hydraulic pump. #70 in the parts illustration.

Every piece of rubber hose connecting pieces of the suction line together including at the oil cooler is suspect along with the hose clamps.

If you pulled out the oil strainer/screen, the seals #120 on its banjo bolt are suspect.

Lastly, the seal you installed in the pump....

Any of these locations can be allowing air into the hydraulic system and foaming the oil.

Dave

 

[Work Horse]

Did you replace the O rings on the banjo bolt attaching the suction line to the hydraulic pump. #70 in the parts illustration.

Every piece of rubber hose connecting pieces of the suction line together including at the oil cooler is suspect along with the hose clamps.

If you pulled out the oil strainer/screen, the seals #120 on its banjo bolt are suspect.

Lastly, the seal you installed in the pump....

View attachment 44931

Any of these locations can be allowing air into the hydraulic system and foaming the oil.

Dave

Dave,

I did replace the O-rings/crush washers on the banjo bolts and I got them as tight as I could. (May have to double check that) I also replaced all rubber hoses while I had everything apart. I haven't touched the screener plug since cleaning it out a couple months ago, but will see if it needs tightening.

If the seal I installed is faulty would it allow air to enter the hydraulic system from the engine, that and possibly engine oil?! I thought when those seals went only hydro oil could go into the engine and not the other way around?

Is there a way of troubleshooting where a leak is, or do you just have to go through every bolt, clamp, hose, etc until you find it?

 

[Work Horse]

So I double checked all my connections and re-tightened all my connections and I still have a small leak at the banjo bolt on top of the pump. Gaskets looked great (their new), but even with a ton of tension their still leaking. I'm not sure how tight it should be, but the old O-ring was "crushed" down to size and it didn't leak.

BTW, got a few pictures of the pump before I reinstalled it. Any thoughts on that? Maybe I F'd up the new seal.. although it was very straightforward.

 

[Lil Foot]

Not a hydraulics expert, but I have always been told that foaming is usually caused by leaks on the suction side- leaking seal, pin hole in a hose, that sort of thing.

 

[Dave_eng]

These comments may not be relevant to your current situation, you will have to judge.

Snap rings need to be installed in a certain orientation if expected to stay in place.

Seals and O rings need to be lubed before installation. Otherwise it is easy to tear or nick them.

The small leak on the high pressure side of the pump will not cause the air problem you have.
Dave

 

[Work Horse]

These comments may not be relevant to your current situation, you will have to judge.

Snap rings need to be installed in a certain orientation if expected to stay in place.

Seals and O rings need to be lubed before installation. Otherwise it is easy to tear or nick them.

View attachment 44978
The small leak on the high pressure side of the pump will not cause the air problem you have.
Dave

Dave, thanks again for the reply! I did not know about the grease on the O-rings, or snap ring position. I may have to reposition the snap ring and see what happens.

So, if the pump seal fails it can allow air to enter the system? I'm just curious because before it was leaking oil into the crankcase, can it go both directions?

Also could the hydraulic pumps gasket (that bolts onto the block) allow air to enter the system? I would have thought it would leak oil, which it isn't.

 

[GEP]

Dave, thanks again for the reply! I did not know about the grease on the O-rings, or snap ring position. I may have to reposition the snap ring and see what happens.

So, if the pump seal fails it can allow air to enter the system? I'm just curious because before it was leaking oil into the crankcase, can it go both directions?

Also could the hydraulic pumps gasket (that bolts onto the block) allow air to enter the system? I would have thought it would leak oil, which it isn't.

Like it bean said air can be a problem. Also how does your oil look if it is like milk you could have water in the system

 

[Dave_eng]

Dave, thanks again for the reply! I did not know about the grease on the O-rings, or snap ring position. I may have to reposition the snap ring and see what happens.

So, if the pump seal fails it can allow air to enter the system? I'm just curious because before it was leaking oil into the crankcase, can it go both directions?

Also could the hydraulic pumps gasket (that bolts onto the block) allow air to enter the system? I would have thought it would leak oil, which it isn't.

My point re snap ring was, if installed improperly, how do you know the seal is still in place.

I am not certain if air can enter the system through the pump shaft seal as many factors would be involved.

My comments re lubing seals and O rings had to do with the leak you have on the pump discharge.

The pump to engine gasket would not be involved in air leakage.

dave

 

[Work Horse]

Like it bean said air can be a problem. Also how does your oil look if it is like milk you could have water in the system

If I'm looking at the oil on the dipstick it's nice and clear, drained a bit out of the axle yesterday (just to see what it looked like) and it looked nice and clean. When it comes out the vent tube it looks milky - likely due to all the bubbles.

I believe I may have introduced a small amount of water into the system when I had the oil cooler off and I was spraying degreaser off the engine. How much does it take to cause an issue? I didn't spray directly into the open line and it was for only a few seconds. To be on the safe side I'm gonna get more fluid and flush the system out later today.

 

[Work Horse]

My point re snap ring was, if installed improperly, how do you know the seal is still in place.

I am not certain if air can enter the system through the pump shaft seal as many factors would be involved.

My comments re lubing seals and O rings had to do with the leak you have on the pump discharge.

The pump to engine gasket would not be involved in air leakage.

dave

Thanks for all the info. I just flushed the hydro fluid and all seems a lot better. It appears that a little water can cause big problems in a hydraulic system... I didn't get to address the leak on top of the hydro block yet, but I think this is a step in the right direction.

 

[Dave_eng]

Thanks for all the info. I just flushed the hydro fluid and all seems a lot better. It appears that a little water can cause big problems in a hydraulic system... I didn't get to address the leak on top of the hydro block yet, but I think this is a step in the right direction.

It is really good when an owner is completely open with any aspect of servicing that they have done perhaps incorrectly.

For those offering advice, it helps them focus and find a solution, for other owners they learn the not to do simple things they may not have realized.

Dave

 

[Work Horse]

It is really good when an owner is completely open with any aspect of servicing that they have done perhaps incorrectly.

For those offering advice, it helps them focus and find a solution, for other owners they learn the not to do simple things they may not have realized.

Dave

Thanks Dave,

If there's something I've learned over my long 28 years of life, (lol) it's better to lay everything out on the table. Even if what you did might be stupid, or ignorant. Also, I've been trying to give back to others on these forums - with whatever knowledge I have attained. Because really, I've learned just about everything over the years on forums like this one. Appreciate all the help, hopefully all is good from here! (Laughs at self)

 

[GEP]

Thanks for all the info. I just flushed the hydro fluid and all seems a lot better. It appears that a little water can cause big problems in a hydraulic system... I didn't get to address the leak on top of the hydro block yet, but I think this is a step in the right direction.

Dave just let the oil you drained out set for a while, you will see what you have. The water will separate
enough just remember the water will be on the bottom of your container, it would be best to use a glass jar.