John Deere 550 Transmission Problems

[targetpracticec]

My JD 550 pushes dirt fine when first started up. It will even spin the tracks when pushing too much dirt. However, once it warms up after 10 -15 minutes it gets slower and slower and weaker and weaker, especially when shifting from forward to reverse or vice versa. It gets so bad that it will hardly engage in gear and move. Sometimes stepping on one or both foot brake/clutch will help it engage, but even then it is slow and weak to move and push dirt. I tested the pressure at the main port while pushing dirt and only measured 150 PSI when it was cold, and once it warmed up it was about 125-130 psi. The service manual states "The main pressure test point (5) should read 60 to 110 psi (410 to 760 kPa) (4 to 8 bar) in neutral and 255 +/- 12 psi (1760 +/- 80 kPa) (18 +/- 1 bar) when in range". So what I measured is well below the limits. When idling it measures 70 psi which is within spec.

I am in the process of changing the transmission oil filter element and cleaning the strainer when found some wires, screws and a small stick in the transmission screen. Also, there was twice as much oil in the transmission (about 20 gallons vs 9.7 gallons). I also noticed that the outlet pipe that connects to the outlet of the screen to kind of wiggle freely up and down, and about 1/4" front to back and wonder if I possibly have a bad connection on the other end of that pipe which I am guessing connects to the transmission hydraulic pump. Before I put it back together and fill it with oil (as it it quite a pain to drain the oil) I thought I would ask this group if you would recommend to just put the screen back in and fill it will oil or would you recommend tearing it down and looking at the hydraulic pump or other suggestions. Attached are some pics of the foreign objects found in the screen. Any ideas where the 2 screws in the screen came from? They look like some type of set screw.

 

[Welder Dave]

Somebody has been into it in the past. The guard around the strainer looks homemade and it's a pretty poor attempt at brazing. A serial number will likely help get better responses but unfortunately I think some trans. parts may be obsolete and 550 transmissions are known to be very expensive to repair. Hopefully it's something simple.

 

[mg2361]

Welcome to HEF targetpracticec!

 

[targetpracticec]

Somebody has been into it in the past. The guard around the strainer looks homemade and it's a pretty poor attempt at brazing. A serial number will likely help get better responses but unfortunately I think some trans. parts may be obsolete and 550 transmissions are known to be very expensive to repair. Hopefully it's something simple.

Thanks for your reply Welder Dave. The
Serial number is C 294072T

 

[targetpracticec]

Welcome to HEF targetpracticec!


View attachment 322810

Thanks mg2361. I do believe you quickly identified where those set screws may have from! Any idea on what may be causing the transmission to loose power as it warms. Is it possible that these set screws may cause this type of problem.

 

[mg2361]

If that coupling were an issue, it wouldn't be affected by temperature. With low main pressure, you have either a pump going bad, or excessive leakage in the circuit. You did rule out control linkage adjustment/clutch pedal adjustment/steering clutch issues first?

Seeing that black stuff in the suction screen, I suspect clutches are wearing out, so the above checks will most likely prove futile.

Like Welder Dave said, most of the parts for that machine are obsolete. I just looked and you can't even buy the clutch discs and plates from Deere. You would have to source parts elsewhere.

 

[targetpracticec]

I wouldn't say that I totally ruled outage control linkage adjustment/clutch pedal adjustment/steering clutch first as we (me and the previous owner) have never even adjusted the clutch/brake and between the two of us owned it for for about 25 years. I know that I had to press excessively hard on the right foot pedal to get it to steer in the past, but it did work. Like many things, finding the right information on how to fix it take some work, and years ago forums, YouTube and internet searches were not quite so available. So like many things you kind of just put it on the back burner and then 10 or 20 years later it finally becomes a higher priority in hopes of finding more information. Long story short, poor maintenance over the years. However, it seemed to work pretty much fine over the years, hence the excuse/saying if it was not broke don't try to fix it as you may screw it up, but I should have been at least changing the fluids. Honestly, it was quite hard to even find information about how to clean the transmission screen. I only found out from reading a forum similar to this one. Since then I have acquired the operators and service manuals which have been quite helpful, but neither manuals explained very clearly where the transmission screen was located.

I do suspect that the pressure is dropping when it gets hot because the fluid is getting thinner and probably leaking more internally. I wish I could see how it was plumbed before and after the transmission pump. My plan currently is to put it back together and fill it with the proper amount of fluid to see if changing the element and cleaning the screen helps performance. I suspect it may not move. If that is the case I am suspicious that the problem may be on the inlet side of them pump. I am guessing that over the years I kept adding transmission fluid to compensate for a leak on the inlet to the pump side and having excess fluid may have somehow bypassed the screen and entered into the pump by flooding the outside of the pump inlet tube...just a theory. Is there any possibility could have help or was that just a coincidence?

I am still looking for a parts catalog (online or download) and would appreciate if anyone can point me in the right direction. I am inclined to pull the motor and transmission. I suspect that gear pump may be worn and some connections to and from it may be leaking. I would like to see the parts diagrams prior to tearing it down. Thanks again for all the help mg2361 and Welder Dave.

 

[mg2361]

Online parts catalog here.

 

[targetpracticec]

mg2361 - thank you so much for the link. Took me a few tries but I finally found my machine. Here is the link for my machine:

https://partscatalog.deere.com/jdrc/navigation/equipment/17651

I posted it in case anyone else out there has a JD 550 and is having similar issues.

After looking at the transmission hydraulic system, I can not find a picture showing the connection from the transmission screen to the pump.

I found a pic showing only the transmission screen, but I can not identify the tube and oring coming from the screen to the pump. I see a parts list for the transmission case lubricating oil lines, but I don't think that is what I am looking for. I would think the tube connecting the screen to the pump would be shown since it has atleast 1 oring on it and it would be a replacement item. The reason I am looking for that is because that pipe that inserts into the outlet of the screen is very loose on the other side which I would expect to plug into the pump (just guessing here) and I suspect that it is not connecting properly to the pump inlet. Without pulling the engine and torque converter I can not see where the oil pump or that inlet to the pump. Any ideas on how to verify that inlet to the pump is properly connected?

 

[mg2361]

 

[targetpracticec]

Thanks again mg2361! I didn’t even think about looking under the torque converter for hydraulics.

 

[Steve Austin]

Check your lube pressure. There should be a lube pressure gauge on the instrument panel but may have been removed or not working.
Under the floor plate there is a lube pressure test port clearly marked has 1/8-inch pipe plug.
Check cold and after warmed up i suspect you will see a drastic drop after warm this will indicate a lot of internal leakage at quills and sealing rings on these twin disks transmissions.

 

[targetpracticec]

Hi Steve, thanks for troubleshooting advice. I had to do a little research in the service manual to identify the port you are talking about. On the pic JD550 Test Ports Location, looks like port 3 is where I should test the lube pressure as you describe. I found some information and included pages from the service manual. Looks like the normal lube pressure in in the range 25-39 psi. Once I put the screen back in I will test that.

On a different note, one thing I noticed from reading the service manual, it appears that it is not necessary to remove the engine to remove the oil pump (see JD550 Oil Pump pages 1 and 2). Is this correct?

 

[Steve Austin]

Yes, transmission oil pump can be removed without pulling engine.
If you do remove pump there are 2 threaded holes in flange of pump for pulling.
Use caution pump flanges have been broken during pulling process especially if someone has used high strength sealer on flange and ports.
Port 3 is correct the dash gauge is for converter pressure if my memory serves me correctly that pressure will be very low also indicating excessive internal leakage.
I would research parts a viability before i got too deep into this, would be a lot of hard work to find out no parts for repairs.

 

[targetpracticec]

Gotcha! Thanks

 

[targetpracticec]

So, after putting it back together and filing it up with transmission fluid, it moved forward and reverse a few times and seemed alright, but then it stopped moving all together. I haven't check the pressure as Steve suggested yet, but I am thinking about pulling the engine and taking a look at the torque converter and transmission. Before I get too far into this, I would like to have located some replacement parts. Does anyone have a source proven transmission rebuilder or a place to buy used or rebuilt transmissions for a JD 550? I am located in South Western Pennsylvania area so something in that area is preferred but I am open to all suggestions even it it means traveling a bit.

 

[jd550b-owner]

Did you have any luck with your JD 550?
I have a JD 550B and I am having very similar issues to what you were having.

 

[redneckracin]

Any more follow up on this? Can the pickup screen be cleaned by just removing the cover plate?

 

[targetpracticec]

Hello folks, sorry it's been a while. I am sorry to report that this project hasn't moved since my last postings. I am thinking about getting a guy who works on this stuff for a living to rebuild the transmission to get it up and going again.. maybe this winters project.

 

[Welder Dave]

Be sitting down when he tells you the cost.