BX2660 - Bypass valve whine when hot

[mjribeiro]

Hi guys - at about 20hrs my FEL and 3pt hydraulics started to whine loudly when raised, lowered, or curled. The same noise was present when reaching the end of piston travel and hitting the bypass valve. It wouldn't do this until the oil was hot. When cold it was quiet. At 26 hours I changed the hydro oil and filter, switching to SUDT.

Still no noises now when cold, but when hot, lowering the FEL and dumping the bucket makes a loud whine even when empty. Raising and curling up make no noise. The same noise is present when reaching end of travel on any piston. Again, only when hot.

Do you think there is something wrong with the bypass valve? Getting it to the dealer is kind of a pain. I will, but I want to make sure I'm not going to get it there only for them to tell me it is a 'normal' situation on a BX.

Thanks!

 

[EE_Bota]

Hi guys - at about 20hrs my FEL and 3pt hydraulics started to whine loudly when raised, lowered, or curled. The same noise was present when reaching the end of piston travel and hitting the bypass valve. It wouldn't do this until the oil was hot. When cold it was quiet. At 26 hours I changed the hydro oil and filter, switching to SUDT.

Still no noises now when cold, but when hot, lowering the FEL and dumping the bucket makes a loud whine even when empty. Raising and curling up make no noise. The same noise is present when reaching end of travel on any piston. Again, only when hot.

Do you think there is something wrong with the bypass valve? Getting it to the dealer is kind of a pain. I will, but I want to make sure I'm not going to get it there only for them to tell me it is a 'normal' situation on a BX.

Thanks!

We have had a rash of noise complaints, and we rarely get to hear the noise, and even when we do, it is still not much help.

I think we need to place much more emphasis on "change." Since what you are saying does not sound right, and it is also a CHANGE, I'd say there is something wrong. Have it looked at since it is under warranty.

 

[oldnslo]

Does the FEL still have the same lifting capacity and lift speed? If yes probably not the System relief. I agree with EE, something has changed and at those low hours it should be a warranty issue. let the dealer handle this since if you start tearing things apart they may lay the blame on you and fight any warranty claims.

Roy

 

[mjribeiro]

I'm definitely letting the dealer handle any warranty repairs. Just trying to make sure I'm not making a trip only for them to tell me its normal.

As per lifting capacity & speed I believe it's the same - but, lifting is not when the noise occurs.

Thanks guys!

 

[Texas Fella]

Lower your 3 point all the way down and see if the noise goes away. In some cases, the 3 point will be mis adjusted and cause it to dump over relief all the time. Often when this happens, the customer does not notice it because there is not "change" in noise level or type (it dumps to relief from the instant that you crank the tractor). What the customers hears is the additonal noise created when lowering the loader and that additional oil (leaving the loader cylinder) must also pass over relief (because it must travel to tank via the 3 point). Usually, loader dump is slow also, so it does not match you symptoms exactly, but I would think it is worth a shot before hauling it in. If it is out of adjustment, your ops man should tell you how to adjust it correctly. Like I said, not likely, but I would give it a shot.

 

[mjribeiro]

Lower your 3 point all the way down and see if the noise goes away. In some cases, the 3 point will be mis adjusted and cause it to dump over relief all the time. Often when this happens, the customer does not notice it because there is not "change" in noise level or type (it dumps to relief from the instant that you crank the tractor). What the customers hears is the additonal noise created when lowering the loader and that additional oil (leaving the loader cylinder) must also pass over relief (because it must travel to tank via the 3 point). Usually, loader dump is slow also, so it does not match you symptoms exactly, but I would think it is worth a shot before hauling it in. If it is out of adjustment, your ops man should tell you how to adjust it correctly. Like I said, not likely, but I would give it a shot.

Thanks Fella - I will definitely give that a try.

 

[EE_Bota]

Hi guys - at about 20hrs my FEL and 3pt hydraulics started to whine loudly when raised, lowered, or curled. The same noise was present when reaching the end of piston travel and hitting the bypass valve. It wouldn't do this until the oil was hot. When cold it was quiet. At 26 hours I changed the hydro oil and filter, switching to SUDT.

Still no noises now when cold, but when hot, lowering the FEL and dumping the bucket makes a loud whine even when empty. Raising and curling up make no noise. The same noise is present when reaching end of travel on any piston. Again, only when hot.

Do you think there is something wrong with the bypass valve? Getting it to the dealer is kind of a pain. I will, but I want to make sure I'm not going to get it there only for them to tell me it is a 'normal' situation on a BX.

Thanks!

If I had to guess right now, your symptoms are quite odd, so I would have to make an odd guess. It could be a problem with the "tank" quick connect on your front end loader. Somehow, it is restricted due to unequal poppet openings because of poppet spring wars, and somehow its worse when hot. How's that for a WAG. It is completely consistent with the symptoms, since the noisy movements are actually the easiest movements (due to the gravity assist) therefore the whine is less related to pressures, and more related to flow to tank.

I'm probably wrong, but logic dictates that I would have to check there very early.

 

[oldnslo]

If I had to guess right now, your symptoms are quite odd, so I would have to make an odd guess. It could be a problem with the "tank" quick connect on your front end loader. Somehow, it is restricted due to unequal poppet openings because of poppet spring wars, and somehow its worse when hot. How's that for a WAG. It is completely consistent with the symptoms, since the noisy movements are actually the easiest movements (due to the gravity assist) therefore the whine is less related to pressures, and more related to flow to tank.

I'm probably wrong, but logic dictates that I would have to check there very early.

EE,
good logic but.... on the BX models they use regen for dump so there would be no tank line flow. Lowering the FEL would generate tank flow.

If this the spools are not centering correctly I would expect noise all the time or some unwanted movement of the FEL.

Not exactly sure how the control valve on the BX'es are ported but I would suspect the pressure and tank lines are hard plumbed. Does the tank port feed the 3PH. On the BX this is also a spring centered valve so I would expect noise from it all the time if it is not centering properly.

Roy

 

[EE_Bota]

EE,
good logic but.... on the BX models they use regen for dump so there would be no tank line flow. Lowering the FEL would generate tank flow.

If this the spools are not centering correctly I would expect noise all the time or some unwanted movement of the FEL.

Not exactly sure how the control valve on the BX'es are ported but I would suspect the pressure and tank lines are hard plumbed. Does the tank port feed the 3PH. On the BX this is also a spring centered valve so I would expect noise from it all the time if it is not centering properly.

Roy

Roy, you know what I was trying to do...find a single point of failure that could explain why easy work is now hard, but hard work is as easy as ever. But I am WRONG and you are right sir.

I was basing my speculation, a long shot at best, on the experience I had here.
http://www.tractorbynet.com/forums/hydraulics/176685-hydraulic-quick-coupler-problem.html

But, you are quite correct, about the regen. I considered regen, since my loader has regen ONLY on dump, but I presumed he has the nicer valve, which has two position dump, and I thought first position was normal dump, and second position was regen, and guess he would not use regen if noise was present. I glossed over and assumed way too much!

But, it gets worse, I forgot that the guys with the really nice BXs have the new loader valve which stays with the tractor. So, instead of dealing with pressure, power beyond, and tank, and having to manually connect the pressure to power beyond so that the lift can work with the loader removed, they now have (I imagine, due to lack of the loop) four quick disconnects that represent the work ports of the two spool loader valve (with no loop reconnect necessary since the valve is still present.)

So, what was a long shot, is a longer shot, requiring failures of two quick disconnects, one per circuit, and that just ain't happening unless the OP changed his disconnects to a bad brand, like I did, and he would have mentioned that.

It's a pity though, because we are still left with the dilemma of a tractor straining, even with the help of gravity, to do easy work, but no apparent strain doing hard work.

I was trying to help the OP, not waste his time, so thanks for correcting my error(s.) I will be glad when the answer is known, because this problem is confounding me. How could a tractor lift its boom easier that lowering it?

 

[oldnslo]

I was trying to help the OP, not waste his time, so thanks for correcting my error(s.) I will be glad when the answer is known, because this problem is confounding me. How could a tractor lift its boom easier that lowering it?

EE,
I think we are all trying to help and this one is very confusing. As you stated noise is typically associated to trying to do work. I have the BX1850 but have not looked at how it is plumbed. I think the FEL feeds oil to the 3PH but not sure. When using the FEL the one constant is the Priority flow control but that again is in the system all the time. Charge pump relief same thing, should be in the system all the time. My BX is all hard plumbed so....Really grasping for straws but could there be some mechanical line vibration under certain conditions that is causing this.

As far as lifting load easier than lowering some of the BDSL (Bi-directional hydraulic self-leveling) systems do exactly this. When lowering the FEL you must curl the bucket back to keep it level. Curling the bucket requires pressure which means you must restrict the return flow from the lift cylinders. One of the reasons why BDSL is not very common on FEL's.

mjribeiro,

A simple test if you can.

Try feathering the FEL lever to limit lift or lower speed and see if you notice a difference in the engine sound and the hydraulic noise. Doing this should raise the hydraulic system presssure which should make the engine work harder and also operate the relief mode in a "Partial" flow mode. Some relief valves have certain flow rates that cause them to sing like a canary. Just curious to see if this is what you are doing and not even realizing it.

Again another long shot but it should eliminate another variable.

the search goes on.

Roy