Older TN Series Hydraulic Drain Plug Locations

[Tractor2Big4Me]

Hi, everyone! New member here. Forgive me if this has been addressed, but I couldn't find it by searching every term I could think of.

I bought a 2003 TN65 4WD open station tractor that only has 575 hours on it. The engine oil has been changed regularly and it appears that the hydraulic filter has been changed. The previous owner didn't use the tractor very much at all and he couldn't remember if/when he had changed the hydraulic fluid itself. The fluid is clean and clear. I want to change it since it has probably been in there a long time. I bought 15 gallons of the Velocity Ambra 134G fluid recommended by the dealer so I can replace the main hydraulic fluid and the fluid in the front drive components.

Here is the problem. There are supposed to be four drain plugs and I can definitively locate only two of them. The big 27mm drain is obvious. The one on the rear edge right under the drawbar looks legit. I'm not sure about the other two. Here is what I think. Can anyone confirm if these are the correct ones?

Thanks!
--Tom

 

[Tractor2Big4Me]

The first picture above is obviously the big 27mm drain. The next two are the ones I am not sure about--one is located on each segment of the transmission case. The one on the right is located at the rear under the PTO shaft--I believe it is correct. Any insight would be greatly appreciated!

 

[Jerry/MT]

The first picture above is obviously the big 27mm drain. The next two are the ones I am not sure about--one is located on each segment of the transmission case. The one on the right is located at the rear under the PTO shaft--I believe it is correct. Any insight would be greatly appreciated!

Do you have the operator's manual? If not, you should get one. You can order them from NH or you can find them on the ebay. Maybe the previous owner still has his. Since you say the fluid appears to be "...clean and clear..." get the operator's manual before you do anything.

 

[TractorTech]

All are drain plugs. They are located at the low points that oil would be trapped within the case. You 3rd picture is dark and it is hard to tell where it is exactly, but you really can drain 99% of the oil with the large plug and the rear axle plug.

 

[Tractor2Big4Me]

Thanks for the replies. I have the operator's manual, but the drawings in the manual are not detailed and the first picture (Figure 46, page 3-23) doesn't look anything at all like the the two forward plugs. I also checked the service manual (I have the PDF), but I didn't see any more useful information. I watched some YouTube videos on larger and newer New Hollands and it looked like they were draining everything through the main drain plug. The plugs on my previous tractor (a much smaller Cub Cadet) were pretty obvious and the drawings in the owner's manual were pretty accurate. One farmer neighbor, who used to work on NH tractors at a local dealership, said he never worked on these "little" tractors. Another farmer friend said it looked like I had the correct plugs identified, but he had never had a similar tractor. I thought I would check with a wider audience before I started pulling plugs.

Thanks again for the confirmation!

 

[Tractor2Big4Me]

BTW, when I said the fluid is "clean and clear", I meant there was no discoloration, evidence of moisture, or evidence of being overheated. It basically looks like good hydraulic fluid. The previous owner stored the tractor in an insulated and heated pole barn, so is has not had a rough life.

 

[Tractor2Big4Me]

Just a post-change follow-up in case another inexperienced soul goes down this path in the future. The four plugs pictured above were correct. As TractorTech said, the rearmost two plugs (the big 27mm plug and the one under the PTO shaft) were responsible for almost all of the oil coming out. The front two plugs were lucky to have 0.5-1 gallon total. I used two 5-gallon buckets for the main drain operation with heavy disposable gloves on. I pulled the 27mm plug and kept it close to the drain hole. When the bucket was close to being full, I put the plug back in and swapped the buckets. The second 5-gallon bucket also held the rest of the fluid from the rearmost plug (under the PTO). I used a third 5-gallon bucket for the front plugs (not much fluid came out) and a regular oil pan for the massive filter. The fluid coming out was in very good shape (visually). There were minor amounts of metallic dust on the magnetic plugs, but nothing serious.

I used Viscosity 134G fluid at the recommendation of the local CNH dealer. They said that was the OEM fluid for the tractor.

If you haven't done this before, you will need:

1) Large metric socket set (22mm for smaller drain plugs, 27mm for big one). You will want a breaker bar or very large ratchet because the plugs can be tight.
2) I believe the hex plug drain was a 10mm--I bought a hex socket set from Harbor Freight. The front hub plugs are 12mm hex.
3) Very large strap wrench for the filter (I bought a GearWrench 6" capacity nylon strap filter and it worked perfectly)
4) Very large drain pan or several 5-gallon buckets
5) Long, slender funnel for main reservoir and flexible funnel for front end fill plugs
6) I used the loader to raise the front end and manually rotated the wheels between the draining (plug at bottom) and filling (plug horizontal) positions
7) Watch for copper washers on the drain plugs--don't let them fall into the catch bucket

The job was not really difficult and cardboard on the floor caught all of the splashed fluid. Overall, it took about 4.5 hours to drain and refill the main fluid and front drive components (axle and hubs). It will definitely be faster the next time.

The main hydraulic reservoir took the expected 11 gallons of fluid. By the time you add the gallon and change to the front end and part of a quart to each hub, you will probably come out ahead buying three 5-gallon buckets of fluid.

Hope this helps another newbie someday.