Ford Tractor Hydraulic System

CONDENSATION

If you use your tractor daily, skip to the next discussion. Daily use of your tractor will constantly evaporate any moisture from condensation. But if your tractor has been sitting for a while, or you generally leave it outside in the weather, it is a good idea to drain off any water that may have accumulated in the sump (not a bad idea to also do this to the engine oil sump while you are under there). In humid months, you can collect quite a bit of water in the sump just from condensation.

Carefully loosten the drain plug on the hydraulic pump housing. Get it just loose enough to drain off any water and screw it back tight as soon as you start getting oil. Oil floats on water, so that should get rid of most of the water in the sump. If you get a lot of water (more than a point or so), check your boot on the shifter for cracks. A $5 shifter boot is much cheaper than five gallons of hydraulic oil or a frozen and broken hydraulic pump!

CHANGING THE HYDRAULIC FLUID

The N tractors have a common sump for the rear end, hydraulic pump and transmission. To completely drain the system, there are three drain plugs. Two large plugs under the transmission and pump and one smaller pipe plug under the differential housing. There is only one filler cap located on top near the gear shift.

When you are ready to drain the sump, you will need a container that holds about 5-gallons.

When changing the fluid, try to flush as much of the sludge as possible out with the old fluid. Just like changing the oil in the crankcase, it is better if you do it when the fluid is at least warm. It runs out quicker and more stuff is suspended in it. You can use one drain pan to catch the fluid by starting with the pipe plug under the rear end and moving forward to the large plug at the hydraulic pump and then the last one at the transmission. Some recommend flushing the system with kerosene. They pour in a couple of gallons, start the engine, engage the PTO and run the lift up and down a couple of times. Then they remove all three plugs and let it drain overnight. This procedure of-course requires three drain pans.

The original Ford recommended fluid for the 8N hydraulic sump was mild EP Gear Oil conforming to Ford specification M-4864-A and B, SAE 80 below +32 degrees F, and SAE 90 above +32 degrees F. The new Ford recommended fluid is Ambra Multi-G 134 (NH-410B) synthetic fluid meeting Ford M2C134D specifications. The current brand name being sold at the New holland dealer is Ambra. It was running about $40 for five gallons the last time I bought it. Some people stick with the original 9N spec. and use a straight 80 or 90-W mineral oil. The modern equivalent of 90w mineral oil is TSC Traveller brand GL-1 or NAPA part number 65-205. Those are be less expensive, but the Multi-G 134 synthetic is good from -5 to 120 degrees F, and it is a NUCH better combination hydraulic/gear lubricant for the 8N tractor.

Replace the three drain plugs and then remove the bottom bolt from the inspection plate that has the hydraulic dip-stick. Start filling the sump and stop when the fluid begins to leak out of the bolt hole. That is all you need, any more will just leak past the axle seals and get on your brakes. It usually takes 4-1/2 to 4-3/4 gallons not 5 as stated in the owners manual. Pull the dipstick and, if necessary, make a new mark that corresponds to the correct level.