500 Hour Service Interval Guide for a John Deere 85G Excavator – Part 6

A heavy-duty mechanic leans on a John Deere 85G mini excavator

Previously, we changed the cabin air filter.

In this post, you’ll learn how to replace the final drive oil on a John Deere 85G Excavator.

We also have a video version on the Fortis HD YouTube channel. Check it out.

Need to save time? The following table shows every filter you need for the complete 500-hour service interval:

Item OEM Part Number
Aftermarket equivalent
Baldwin Donaldson Wix Blumaq
Hydraulic Return Oil Filter 4450002 PT9443 N/A N/A N/A
Hydraulic Breather Filter 4437838 PA5316 N/A N/A N/A
Engine Oil Filter MIU800650 B161-S P502051 51568 N/A
Fuel Filter MIU805005 BF9910 P553995 N/A N/A
Water Separator Filter MIU802421 N/A N/A N/A N/A
Water Fuel Separator Housing + Plastic Bowl MIA885254 N/A N/A N/A N/A
Pilot System Oil Filter 4630525 N/A N/A N/A N/A
Primary Engine Air Filter FYD00001541 N/A N/A N/A N/A
Secondary Engine Air Filter FYD00001327 N/A N/A N/A N/A
Cab Fresh Air Filter 4S00640R N/A N/A N/A N/A
Cab Recirculating Air Filter FYA00011003 N/A N/A N/A N/A
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Drain the Final Drive Oil

Arrows pointing at the final drive's up, level, and drain plugs on a John Deere 85G Excavator

Start by parking your machine so the plugs of the final drive are in the following positions:

  • Up plug – 12 o’clock.
  • Level plug – 3 o’clock.
  • Drain plug – 6 o’clock.

Get a plastic container to collect the used oil.

On this particular model — John Deere 85G — each final drive takes 1.2 liters of 85W-140 oil.

First, remove the top plug to release pressure within the final drive, allowing the old oil to flow smoothly and quickly out of the system. Use a ratchet with an Allen/Hex key (refer to the operator manual for the correct key size).

Remove the level plug. Oil should come out when removing the level plug. If not, there might be a problem with the housing or the seals.

Lastly, take out the drain plug. Old gear oil looks dark and has a particular smell — burnt or sulfurous.

We recommend sampling your gear oil at the time of service. Refer to the operator manual or the description in the YouTube link of this post for more information.

Add the New Gear Oil

A heavy-duty mechanic reinstalls plugs after pumping fresh gear oil in a final drive

Once it stops draining, reinstall the drain plug.

Start filling from the top plug using 85W-140 oil until it drips out of the level plug.The oil level should stay just below the level plug.

Give the final drive a good clean to check for leaks.

Next Post

In the final post of this series, we’ll flip over the cutting edge on the John Deere 85G Excavator.

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If you don’t have the time to do the service yourself or want to get on a preventative maintenance program for your John Deere 85G, reach out to Tekamo HD to set you up with a heavy-duty mechanic.