550g dozer hydraulic fluid

[jziegler]

I am currently borrowing a 550g that keeps going through hydraulic fluid. I have put in 10 gallons already and the tank is empty. Worked fine when parked uphill on a slope. I am assuming the only way the tank can be empty is if the pump is leaking as the controls are higher than the bottom of the tank. There is no oil under the machine or inside the side door control compartment. I am assuming the 2 line in the side compartment door are the feed and return. Does anyone have any diagrams of the pluming under the floor? Where is the pump? Is it a standalone pump or a tandem in-line with the transmission? The transmission is not gaining any oil. What must be removed to inspect, the hole roll case? The diesel and/or oil tanks?

Thanks.

[Jim B]

I will say I am not familiar with late models like the 550G. I think the hydraulic pumps on those are driven from the transmission. Removing the floor boards may give you a visual on it. Here is a link to the 550G parts book: https://partscatalog.deere.com/jdrc/nav ... ment/77456 .
It has parts drawings that might help you.

You put 10 gallons in it. Over how long of a time span? It seems hard to believe there is no evidence of the loss of that amount of oil. Have you checked in the belly pans under the engine and transmission? It may be a hose leaking when you are working it, then dirt and dust hides it when shut off.
You may need to take some panels off it and look around inside it, with a good light, while someone else cycles the controls and holds them against the relief valve intermittently. Keep clear of moving parts and pinch points while doing this. Also don't use your hands to feel for a leak; oil injected under the skin can be very bad, even fatal.

Have you talked with the person you are borrowing it from? They may have some insight and the manuals. I would want to know this was happening if it was my machine. There is a risk of big dollar repairs here.

[jziegler]

Thanks, 10 gallon in 4 weeks about 10 hr of run time. The cylinder seal are not purfect but it is loosing oil over night so it has to be under the tank. I will pull the floor plate and see if I can find anything. Under the engine looks to be full of dirt.

[Jim B]

10 gallons in 10 hours should be at least leaving some signs on where it is leaking.

If cylinders are leaking externally you may be losing more than you think from them while working. The same is true if there are leaks around the control valve.

I have seen belly pans hold puddles of oil that run out when the machine gets tipped at different angles while working, but seem to be invisible when you try to find them.

As for losing oil overnight without seeing any under the machine. My guess is at least part of what you are seeing is the contraction of the oil as it cools. It is not uncommon for a machine filled to the center of the sight glass when cold, appear over full when it gets hot. By the same token: in the middle of the day, or end of shift, if the oil is hot and looks low, you fill it to the center of the glass. In the morning the oil will likely appear low in the sight glass due to contraction of the oil as it cooled. This would explain having no oil spots under it when setting.

Just some thoughts on what might be going on. Did you talk to the owner to see if he/she/they have any insight on this problem?