D17 Series 4 - hydraulics overfilled

We bought a D17 series IV from my FIL's estate. My middle son wanted one of grandpa's tractors to restore as a 4H project.

First thing we are replacing fluids - he passed 4 years ago and nothing has been changed since then and its maybe seen 10 hours of operation (on a grinder mixer) in that time frame.

We drained the trans hydraulic system from 2 locations - under the pump on the right side, under the filler on the left side - apparently we missed the 3rd drain under the tractor. The fluid that came out was creamy yellow looking from lots of water. Right now the system is very over filled because we dumped in 20 quarts without fully draining it (as in it is filled to the neck of the fill hole). What problems are we looking at if you don't pump it down?

Ordered an owners manual and got a CD so we will be printing that off at work in the near future.     

I'd be more concerned about you adding a different type of oil that was in it, and you now have mixed two types. Drain it down and start over. The hydraulic dipstick has two marks on it....ignore the lower mark and use the upper mark after standing still for 15 minutes on level ground.

So the one under the tractor in the seat area is the "gear oil" and does not mix with the oil for the hydraulic system and the PD. We did not mix oils from the two different reservoirs. My understanding is the hydraulic/PD system held 20 or 22 quarts - at 20 quarts (5 gallon) the hydraulic system was over filled (by at least 4 quarts or so). I was being lead to believe all three drain points were for the hydraulic/PD system. Trying to figure out is the 20/22 quarts is correct.          




We plan on draining the "gear box" oil and refilling with 80/90 weight. Most likely this still has the original gear oil in it from the 1960s.


What is the down side of having the hydraulic system overfilled? I know on older IH tractors people were encouraged to overfill the trans-hydraulic system.   

Edited by Hockeygoon - 13 Sep 2016 at 11:40am

Power director and transmission compartments do not mix.   On a Series IV the hydraulics/power director compartment holds 26 quarts, trans/diff is 24 quarts and power steering is 5 quarts.  Make sure lift arm rams are down for the hydraulics/PD.   Mike

We drained from the two drain points for about an hour trying to get as much of the milky fluid as possible out with the filter removed. We did not lower the three point to the lowest position (actually it was at the mid point) so some transhydraulic fluid was still there.


The IT manual I have is Series I to III - apparently the Series IV has a bigger reservoir. Any idea why 20 quarts would overfill a 26 quart system?

The series IV has a totally different hydraulic system than a I-III. Some other things changed as well. Series I-III was a high pressure (3500PSI) low volume system. The IV updated to a more industy standard low pressure (2000PSI) high volume system. Also the IT manuals are known to not be perfect. You'd be better with a genuine Allis operators manual, and maybe service manual. Make sure whatever manual that you buy are for a series IV

   I understand where you were coming from not trying to change the fluid twice, which you need to do, but.....why would you not "want" to change the filter at this stage of the game ?

If overfilled just remove the drain plug and let some out. Run it when you get it to proper level and then check color to be sure you don't need to drain and flush a second time. You may be good with just the one change.

Where did you fill it just ahead of gear shift or under gas tank