John Deere 550G won't move

[willsterman]

I have a 1992 JD550G, pedal steer, 6200 hours, 4 speed transmission that I use periodically for making logging roads. One time last fall when I started the dozer, the "Transmission Oil Temp and Pressure" light came on right away, and when I raised the parking brake lever, the pedals would not release so I could not move the dozer. I shut off the dozer, and a few days later tried again and it worked until mid-winter when the same thing happened. Dozer worked fine a few times again this spring but now I have not been able to get the pedals to release and the dozer to move the past few weeks, giving it a try each weekend.

Unless the temp sensor is bad the temp should not be the problem as the fluid would not be too hot, and would be warm enough now in spring not to cause a problem. Transmission fluid level is fine and looks good. The blade hydraulics still work. When the dozer did move, it seems to work fine. I'm thinking there may be a problem with the transmission control valve.

Any thoughts were to begin looking for the problem before I incur a service call from the nearest dealer which is an hour away?

Thank you!

 

[stumpjumper83]

Were you trying to run steep ground? I've seen a 450g act like that and when we added 10 gal of hyd. oil all was fine. I know on some machines you have to overfill the tranny when on steep stuff, not sure if that applies to 550's or not.

 

[willsterman]

Stumpjumper - the dozer is parked on level ground when started, and operated on gound that is generally level. The fluid level is in the acceptable range (on the lower end) on the dip stick, but I did add a gallon or two to the transmission to try and ensure that wasn't the issue.

Thanks.

 

[S.R.E.]

When did you last change the filter for the transmission?

 

[willsterman]

When did you last change the filter for the transmission?

S.R.E. I have not changed the filter. I purchased the dozer last summer and have used it about 40 hours. I was planning to replace all fluids and filters, but was thinking maybe I should try and fix this problem first, in case I have to dump all the fluid in the process. I don't want to waste the new fluid. I will try replacing the filter only to see if it is restricted.

Thank you.

 

[willsterman]

Well, I was going to change the filter today, and also check the intake screen. Started the dozer for the heck of it first, and it worked fine again today. I'm glad it worked, but intermittent problems are sometimes harder to fix. I will replace the filter next time the pedals don't release when I take it out of park after starting it. If anyone has other ideas besides replacing the filter, let me know.

Will

 

[S.R.E.]

Well, you have only used it 40 hours but, how long since the last guy changed the filter?

 

[Oldtimer82]

Were you trying to run steep ground? I've seen a 450g act like that and when we added 10 gal of hyd. oil all was fine. I know on some machines you have to overfill the tranny when on steep stuff, not sure if that applies to 550's or not.

Stumpjumper83, just wondering if you had any more suggestions on this? I have a 450G that suddenly stopped on the side of a hill (sitting caddy cornered) pedals went down and will not come back up, engine runs perfect and blade hydraulics work fine. Should the oil be showing on the dipstick with it sitting up the hill caddy cornered. I added about 5 gallons of oil, and changed the filter, no luck yet. Wouldn't be so bad if I could get it on level ground.

 

[alaskaforby4]

Stumpjumper83, just wondering if you had any more suggestions on this? I have a 450G that suddenly stopped on the side of a hill (sitting caddy cornered) pedals went down and will not come back up, engine runs perfect and blade hydraulics work fine. Should the oil be showing on the dipstick with it sitting up the hill caddy cornered. I added about 5 gallons of oil, and changed the filter, no luck yet. Wouldn't be so bad if I could get it on level ground.

You could check the micro switch on the park lever. Sometimes id have to raise and lower the park lever a few times in certain weather conditions to get the pedals to pump up.

 

[Diesel Dave]

I suspect the transmission suction screen was uncovered for a few seconds and the transmission pump took a big gulp of air. The suction screen is dead center on the lower bottom edge of the transmission front face. I also suspect the transmission pump is in poor condition and is struggling to pull the oil from the transmission case. I suggest loosening off the transmission pump discharge hose ,roll the engine over on the starter and see if the pump will regain its prime. You may have to slightly pressurize the transmission case at the dipstick tube to help shove the oil to the pump.

 

[Oldtimer82]

I’ve looked in the manual and don’t see anything about a park brake sensor or micro switch, that’s not to say that I’m just not smart enough to find it. Lol If anyone had an idea of what or where this is would you please post a link?

Diesel Dave, thanks for that suggestion, I will try that also. Would it sound an alarm of some sort of it did? I did not have any lights come on, alarms, or noises out of the ordinary. Thanks!

 

[alaskaforby4]

I’ve looked in the manual and don’t see anything about a park brake sensor or micro switch, that’s not to say that I’m just not smart enough to find it. Lol If anyone had an idea of what or where this is would you please post a link?

Its been several years since we owned that dozer, but I remember when I'd load it on the trailer I'd need to sometimes smack the park lever in the down position to get the brakes to engage.
Similarly sometimes when it was freezing Id have to apply heat to the area and work the lever a couple times to get brakes to pump up. But these are all situations when I've been starting and stopping machine, if it happened while operating machine, I'd assume the lever has nothing to do with it and more of an air cavitation issue as Diesel Dave suggested. Could you use the blade and some blocking to get it more level?

 

[Oldtimer82]

Well…… that’s a great idea…. Hadn’t thought of that. I don’t know if I could get it level or not, but could probably help it some. I did try to engage the manual tow pins under the seat but one would not stay down and couldn’t get the other to press down. I was trying to get it into a towable condition to get on level ground. Diesel Dave’s suggestion makes as much sense as anything, but it does seem odd that there were no warning signs at all. Also, I’m a little afraid to start the engine much because I don’t know if it will hurt anything. I am not a mechanic as everyone can probably tell. Lol

 

[Diesel Dave]

I know the steps I would perform but forget to tell the rest of the world
For clarity I should have said , unplug the wire at injection pump solenoid so the engine won’t start when rolling it over on the starter.
I would hate to see you and the machine get a rust control oil bath !

 

[Adam Walden]

You can check pressures at the valves under the seat, to check pressures for the steering clutch check them at p2 and your pressures should be either 180psi or 250psi, find the pressure regulating valve under the seat it will have a sensor on it,take it out and test preasure there if it's below specs of 250 then check the pressure regulating spool under that sensor,

 

[willsterman]

I wanted to follow up and let everyone know that I ended up changing the filter and transmission oil. No problems since then. Thank you for the help!

 

[JBrady]

@willsterman I am glad you got it fixed and 12 years later still no problems! LOL. I also have a JD 550G and had this same issue. I changed the filter and oil, but what I think the real problem was was that the suction hose had become very stiff and was sucking air. I changed it out at the same time and all is well. I also cleaned out about 200 lbs of oily dirt from the bottom pan and found a few end wrenches and a spare key so that was a bonus...

 

[Welder Dave]

That would suck to have your only key fall into a belly pan full of dirt.