How can I test a loader for cylinder vs control valve leakage??

[4lane]

This weekend I finally did the quick loader drift test I OldnSlo mentioned:

TEST: Supported the loader on a jack. Unplugged extend hose on the lift cylinder. Removed the jack.

ASSUMPTION: If the loader drifts, the piston seals are leaking and this leakage is going across the directional valve. OTher assumption is that the control valve leaks as well. However, fixing the cylinders would stop this leak path.

RESULT: The loader did drop, about 1in/30sec - the same drop rate as when using the loader normally.

CONCLUSION: One or both piston seals are leaking, because the oil had a path to return to the tank since the rod end hose was connected. If the piston seals were not leaking and the control valve was leaking, the loader would not have dropped in this test since the cap end hose was disconnected/blocked off.

I've proven that the piston seals are leaking in conjunction with control valve, which combined are contributing to loader drift. Whether or not fixing the piston seals gets the loader drift to a tolerable level is unknown, since we do not know how much the cylinder valve is leaking but at least I've identified one cause, and a cheaper one to fix at that.

 

[LD1]

This weekend I finally did the quick loader drift test I OldnSlo mentioned:

TEST: Supported the loader on a jack. Unplugged extend hose on the lift cylinder. Removed the jack.

ASSUMPTION: If the loader drifts, the piston seals are leaking and this leakage is going across the directional valve. OTher assumption is that the control valve leaks as well. However, fixing the cylinders would stop this leak path.

RESULT: The loader did drop, about 1in/30sec - the same drop rate as when using the loader normally.

CONCLUSION: One or both piston seals are leaking, because the oil had a path to return to the tank since the rod end hose was connected. If the piston seals were not leaking and the control valve was leaking, the loader would not have dropped in this test since the cap end hose was disconnected/blocked off.

I've proven that the piston seals are leaking in conjunction with control valve, which combined are contributing to loader drift. Whether or not fixing the piston seals gets the loader drift to a tolerable level is unknown, since we do not know how much the cylinder valve is leaking but at least I've identified one cause, and a cheaper one to fix at that.

Repeat the same drop test but this time only unhook the retract hose.

Because you have proven 2 things.....1. the seals are leaking a little by and 2. the B port on the cylinder is leaking a little to tank.

So by replacing the seals....you are correct that it wont leak by the B port of the valve any more...BUT.....it can still be leaking past the A port in the valve. And if it is, replacing the seals might not actually solve the initial problem you are targeting

 

[4lane]

Repeat the same drop test but this time only unhook the retract hose.

Because you have proven 2 things.....1. the seals are leaking a little by and 2. the B port on the cylinder is leaking a little to tank.

So by replacing the seals....you are correct that it wont leak by the B port of the valve any more...BUT.....it can still be leaking past the A port in the valve. And if it is, replacing the seals might not actually solve the initial problem you are targeting

I did this test as well. Supported the loader to take the pressure off, disconnected the retract hose, and removed the support. The loader leaked down about 1” every 3min. I redid the initial test again as well and it leaked down 1” every 2min which is the same as when both hoses are connected.

 

[racer86y]

It says the image for test procedure is no longer available.Do you have a updated test procedure?I need it badly.Thanks in advance

 

[Dave M7040]

It says the image for test procedure is no longer available.Do you have a updated test procedure?I need it badly.Thanks in advance

This should be what you are looking for

Dave M

 

[racer86y]

Can't open this for some reason but i did lower bucket to floor jack and let the jack down with lines to control valve unplugged.I leaned on the bucket and it uncurled with ease.What does that mean?

 

[Dave M7040]

Can't open this for some reason but i did lower bucket to floor jack and let the jack down with lines to control valve unplugged.I leaned on the bucket and it uncurled with ease.What does that mean?

It means something internal to one or both cylinders is allowing fluid to bypass a piston.

To identify which of the two cylinders is bypassing, remove one cylinder completely and cap the open lines.

Do your test again. If it acts the same way they at least the one cylinder is bad.

Repeat test with other cylinder to see if acting on its own it does not drop with a little presssure.

Dave M7040

 

[racer86y]

It means something internal to one or both cylinders is allowing fluid to bypass a piston.

To identify which of the two cylinders is bypassing, remove one cylinder completely and cap the open lines.

Do your test again. If it acts the same way they at least the one cylinder is bad.

Repeat test with other cylinder to see if acting on its own it does not drop with a little presssure.

Dave M7040

Thanks,i will try it tomorrow.I paid to have both cylinders rebuilt but........