4520 hydraulics

[phj]

I have a one year old 4520 and it's been great tractor....well almost. It seems the hydraulic system keeps getting air in the system. It has affected both the 3 point hitch as well as the power steering. I can be working in the field and just lose the power steering for awhile or sometime the three point hitch does not seem to want to lift to the full up position or very slowly. Then at times it works great for extended periods. When using the loader you can see it pulse as it's lifting at times as well.

Has anybody else had these types of problems? It's going back to the dealer for the third time to see if they can fix it. If no luck this time around I may have to look at a blue or red tractor.

The tractor does have a power beyond kit for the backhoe, thus far the backhoe seems to work OK. All fluid levels are fine and filters have been changed as well as taking a sample of the fluid looking for metal, which was OK.

Thanks,

Paul

 

[mfreund]

Trade in the dealer instead!!

 

[kennyd]

Welcome to TBN

How do you know it's air in the system?

IF it is air, then the most likely cause is the on the return/suction side of the pump. There is a large metal tube that runs under the tractor from the sump on the tranny to the front where the pump is-it need to be inspected. Also, if it is air-then continuous operation will cause the pump to fail from cavitation.

I know you said filters have been changed, but has the return line screen been removed and cleaned? How many hours on your machine?

 

[jenkinsph]

I would agree it would be on the suction side too. It could be a crack in the pickup tube causing the problem. I would be insistent that the dealer find the source of the problem or try a different dealer.


Steve

 

[phj]

Welcome to TBN

How do you know it's air in the system?

IF it is air, then the most likely cause is the on the return/suction side of the pump. There is a large metal tube that runs under the tractor from the sump on the tranny to the front where the pump is-it need to be inspected. Also, if it is air-then continuous operation will cause the pump to fail from cavitation.

I know you said filters have been changed, but has the return line screen been removed and cleaned? How many hours on your machine?

I am assuming it is air, not sure what else would make the pump cavitate. The tractor has about 130 hours on it and has done this since new. I am assuming it is air for it effects both power steering and the 3pt. lift system.

There are no leaks in the system and it does not always happen. Normally when the steering goes it is for just a few minutes then works has normal. One time the 3pt will lift and the next time it makes a lot of noise and lifts very slowly. If the loader is used a lot it works fine, but let it sit for awhile and it is very rough going up/down until it's been cycled a few times.

The dealer has looked at it before and found one filter in back-wards but everything else seemed OK. It will go back yet again next week, this time it will stay until fixed!

 

[kennyd]

Air leaks on the return suction side of the system are very hard to find, they usually do not leak externally so it is not very obvious. You have 2 pumps that are tied together on one shaft, one is dedicated to the steering and the other to the implements, but they share the return pipe (#14 in the picture) from the sump that I mentioned earlier, and as you can see, there are plenty of places it could be sucking air under negative pressure-and you would never see a drop of oil leaking out.

The hose (#16), pipes (#14 and #10), filter, filter head and packings (#9 and #11) need to be inspected very carefully.

When this happens, you need to look in the sight glass and filler neck and see if the fluid is foamy looking-that will indicate air entrainment.

 

[phj]

Air leaks on the return suction side of the system are very hard to find, they usually do not leak externally so it is not very obvious. You have 2 pumps that are tied together on one shaft, one is dedicated to the steering and the other to the implements, but they share the return pipe (#14 in the picture) from the sump that I mentioned earlier, and as you can see, there are plenty of places it could be sucking air under negative pressure-and you would never see a drop of oil leaking out.

The hose (#16), pipes (#14 and #10), filter, filter head and packings (#9 and #11) need to be inspected very carefully.

When this happens, you need to look in the sight glass and filler neck and see if the fluid is foamy looking-that will indicate air entrainment.

Kennyd,

First, thank you for your input, it is most appreciated. When you talk of a sight glass are you referring to the dip stick? As far as I know I do not have a sight glass on this tractor.

Also, when I first got the tractor I noticed that when raising the 3pt hitch and using the hydro in reverse I would get a loud growling sound. At that time I check the hyd fluid level and some fairly bright green fuzz would be stuck on the dip stick (HYD). I have not seen any more of that material since the last shop visit when they changed the fluid. Could the material been part of a seal or a filter?

Thanks again for your help,

Paul

 

[kennyd]

Most tractors have a sight glass on the rear of the tranny above/near the PTO shaft for checking fluid level in addition to the dipstick, I just ASSumed yours did-but it may not.

What you had on the dipstick was probably just normal break-in crap that in the system when new, there are always bits of metal and other trash floating around these things from the manufacturing process-that is why the first 50 hour service is so important.

 

[Ken]

I have a 4520 and no sight glass but a easy to check dip stick. Check the loader hoses under right side I have had hose become loose but stll will function notice that curling bucket is slow or fails to raise normal placing on level spot shut off engine and releive press with joy stick reseat the 4 hydrolic connectors. can hear the air/ fluid moving in hoses when restarting the engine.
A month ago a 4300 was brought to me to check the lack of steering and FEL. wouldn't raise. removrd the 2 bolts for the return line to pump and no fluid came out of transmission.
gently moved the seal for the filter and received 6 gal of hydrolic oil before could get out of way and place container to catch. removerd filter and so much trash in washing with diesel it took several brushing to get to flow. flushed the system with diesel and recleaned the filter almost clear so added fluid and system is quiet and works good. This tractor has 1200 hours and only used to bush hog. Where the trash came from ? wood chip and saw dust type of material.
ken

 

[phj]

I have a 4520 and no sight glass but a easy to check dip stick. Check the loader hoses under right side I have had hose become loose but stll will function notice that curling bucket is slow or fails to raise normal placing on level spot shut off engine and releive press with joy stick reseat the 4 hydrolic connectors. can hear the air/ fluid moving in hoses when restarting the engine.
A month ago a 4300 was brought to me to check the lack of steering and FEL. wouldn't raise. removrd the 2 bolts for the return line to pump and no fluid came out of transmission.
gently moved the seal for the filter and received 6 gal of hydrolic oil before could get out of way and place container to catch. removerd filter and so much trash in washing with diesel it took several brushing to get to flow. flushed the system with diesel and recleaned the filter almost clear so added fluid and system is quiet and works good. This tractor has 1200 hours and only used to bush hog. Where the trash came from ? wood chip and saw dust type of material.
ken

Just where is this return line and filter? Does the 4520 have the same line?