Discussion:
Differential Fill and Drain Plugs

I want to drain and fill the differential.

At the front of the differential is a plug with a square recess. Is this the fill plug and should oil be filled to the bottom of this hole? What is puzzling to me is that all the differentials I have encountered take oil to a level just above the bottom of the axle tubes, and therefore below the centre line of the differential. This plug is above the centre line, so the differential will be more than half full of oil if filled up to this plug.

There is another plug further up that has a hex recess, thus taking an allen key. What is this plug for?

I did not jack up the forklift, so I did not see the bottom of the differential. Feeling under the differential, there are two plugs located at the back and towards the bottom of the differential. These have hex heads on them, thus taking an ordinary wrench. Is one of these the drain plug?
  • Posted 19 Oct 2016 08:06
  • Modified 21 Oct 2016 09:06 by administrator
  • By Georg
  • joined 7 Mar'14 - 20 messages
  • Ontario, Canada
1998 426FGCU25 Ser No 67740
Showing items 1 - 2 of 2 results.
Well, I will answer my own questions. I lifted the forklift today and found the drain plug at the very bottom of the differential case. The fill plug is the one at the front of the differential. They are both 1/2 in square recess and can be driven with a 1/2 in extension on a ratchet.

The oil level is to be at the bottom of the fill port.. The fluid capacity of the differential on my truck is 6.4 l and adding that amount after draining the old oil brought the level up to the bottom of the fill port.

I used 75W90 Spirax by Shell.
  • Posted 12 Jan 2017 10:40
  • By Georg
  • joined 7 Mar'14 - 20 messages
  • Ontario, Canada
From Admin....Sorry again, it appears I got the link copied incorrectly last time as well. Here is a new link to the photo, at photobucket dot com that applies to this post.

http://i299 dot photobucket dot com/albums/mm318/george7941/100_0817.jpg
(just change both of the "dot" to a ".")
  • Posted 21 Oct 2016 09:20
  • Modified 21 Oct 2016 09:22 by poster
  • By Admin
  • joined 18 May'04 - 266 messages
  • Queensland, Australia

Post your Reply

Forkliftaction accepts no responsibility for forum content and requires forum participants to adhere to our rules of conduct. Click here for more information.

If you are having trouble using the Discussion Forums, please contact us for help.

Movers & Shakers
Stu Jacover Stu Jacover
Vice president of sales, material handling, Flux Power
President, KION IAS and ITS Americas
Chief executive officer, TVH
Director of sales, national accounts & strategic partnerships, Big Joe Forklifts
Global Industry News
edition #1285 - 11 June 2026
This week in Forkliftaction News , forklift imports into the US now face a lower tariff of 15%, TMH Europe signs a deal to procure recycled steel for equipment production and Amazon unveils its next-gen Proteus AMR... Continue reading