Changing Transmission Oil on 4120

[tinsnip]

Greetings! I put my 4120 to work this winter twitching Pine and hauling lumber. Now that the job is finished, I'd like to do some maintenance on the tractor. During the colder days, I noticed that the hydraulics were sluggish for a bit until the tractor warmed up. This happened even after having used the block heater for 45 minutes prior to starting. Once it was warmed to normal operating temp, everything was fine. Scanning some of the other threads, it seems likely that there's debris in the filters for the hydraulics. Hence my idea to change the oil and clean those filters.

But this is where I run into my ignorance (not uncommon). I had always thought of the hydraulic system and the transmission (eHydro) as being two separate systems. Looking through the manual, I get the sense that they both share the same oil and are connected. Is that true?

If I simply change the oil in the transmission and clean the various filters as described in the manual will I also be servicing the hydraulic system at the same time? Anything beyond what's described in the manual to consider in order to make my various hydraulics happy?

Thanks in advance. (If this has been covered elsewhere, I apologize.)

 

[CrownHawg]

I am curious of this as well. I have put about 40 hours on my 4120 since buying it used last summer. The dealer I purchased if from told me it had had all the "due services" done but I don't really believe him. I currently have 330 hours on it and have noticed my hydraulics getting sluggish as well. I have been contemplating doing this myself, but don't know what I don't know at this point. I have thought about just taking it to a dealer about 20 miles away that I sorta trust. I don't even know WHAT to change/replace. I'll watch this thread closely.

 

[Cidertom]

The systems are common sump. The block heater won't do anything for the transmission. I think that JD has a transmission heater for those really cold days.
I doubt that the screens, filters are plugged if everything operates normally after warm up. I know that on some hydro drive equipment there are cautions in the manual to allow a warmup period to prevent transmission damage. You might look at the fluid options listed in the manual for the temp range you will be seeing.
The interval is 400 hours for the hyd service. It isn't hard to do, but be prepared for the amount of oil you will need to handle. The manual has the process.

 

[RavensRoost]

Your 4120 should have John Deere Hy-Gard low viscosity (JD 20D) for Maine winters, especially if it originally was set up/delivered in Maine. I would think warming it up at fast idle (~1200 RPM) for 10 minutes or so before using it in cold cold temps would be wise.

Of course, you could also have filters and/or intake screen clogged a bit, but I am assuming you are planning to change fluid anyway.

When you change the Hy-Gard, you will need at least one 5 gallon pail to catch the old oil. Check your manual as I needed 2 pails on my 4500, having only one would have made a big mess. Be sure to look at/figure out how you are going to refill it as a 5 gallon pail of Hy-Gard is a bit heavy, hard to pour neatly. I spent about $9 for a very nifty (green!) funnel at JD dealer that I thought was a bit over priced, but turned out to be well worth the $ as it was perfect for what I was doing, even had a large screw on cap for top and smaller one for spout for clean storage. Oh yeah, it also had an eye on the rim so I could wire the funnel in place so a third hand was not needed.

 

[tinsnip]

Thanks gents. I'm pretty sure it'll be about 10 gals of waste oil so two 5 gal buckets are in order. And yup, it was set up and delivered from the dealer about 30 miles from here so I'm assuming they knew what was right for this climate. I will ask though. Thanks for the funnel tip!

Tim

Here's an example of the might of the loader. This 26 foot long pine was 2 feet too long for the sawmill so we had to cut it part way then lift it off the mill and spin it. That's a heavy piece of wood.

 

[Gale Hawkins]

We have an older JD 310B backhoe and was wondering the same about it. I have picked up the Hy-Gard rated oil from TSC and two new Wix filters and was reading about how you change the transmission and hydralic filters at the same time and in my case there is a screen that I need to remove and wash.

The book states I will need to add 8.5 gallons of Hy-Gard rated fluid for this filter change.

My question is how do I get all of the old fluid out so as not to contaminate the new fluid by mixing it with the old. Normally I would just say hang it but the fluid was milky when I bought it a few weeks ago so I do not want the FEL and backhoe dumping back into the new until the old is flushed.

If this has been covered in another thread please point me to it.

My only thought at this time is to pull the return lines from each end of the tractor and let them dump into empty buckets until it looks like new fluid after moving all cylinders while adding more new fluid?

I use this bucket flush method when wanting to do a total fluids change out in the motor home tansmission by putting the return line into a buck. How to do it was covered well on a Ford truck forum.

 

[RavensRoost]

We have an older JD 310B backhoe and was wondering the same about it. I have picked up the Hy-Gard rated oil from TSC....

There are 2 current John Deere Hy-Gard viscosities: normal and low viscosity. The low is JDM J20D and normal is JDM J20C. My manual says low vis/20D is preferred but normal/20C is OK. Either way, make sure what TSC is selling meets one of the two current JD specs and not an obsolete one.

If you are in a cold climate, I would think you would only want the low viscosity 20D. (Not a big deal where I am.)

 

[Gale Hawkins]

It will look to see if the TSC brand spells out more than Hy-Gard. I expect it is the normal weight based on location.

Any thoughts on the question on how to do a full change out of the fluid so as not to mix the bad with the new?

 

[Cidertom]

There isn't a reasonable way to purge all fluid out of the system. For real gross contamination you can loosen the fittings at the cylinders and run the function until the new fluid comes out. This will also fill the cylinders with air, which will make them spongy until all of it is out. One other trick I have seen is use "cheap" hyd fluid, circulate it for a couple of hours and then dump it, the filters and start again.

 

[Gale Hawkins]

I have not found any really cheap fluid but I have thought about that. The dump truck looks like it has never been changed and is in a mess. I thought about draining it and putting what is in the JD and MF in it as a flush.

The JD fluid is a faint white and water forms at the top of the dip stick but it is nothing like as bad as the dump truck hoist. The guy has replaced the two filters and used JD brand Hy-Gard he stated since he bought it 3-4 years ago.

I am going to look at the hydralic fluid flow chart in the shop manual and see the path of the returned fluids before they dump back into the new fluid. I have not talked with JD so I do not know if they are helpful with advice or not.

Thanks for the thoughts.