| How To: Change Transfer Box Case Fluid | |
I have written a step by step guide how to change the transfer box fluid, with pictures.
Difficulty: Easy
Time: 45 minutes
Tools Required:
2 litres of TF0753 / IYK500010 Transfer Case Fluid https://www.smithandallan.com/product/smit...fluid-4187
2x IYF500030 - M16 drain/fill washer (recommended but not essential, unless your existing ones are worn/damaged)
Small ratchet
Small Torque wrench (capable of <30Nm)
H8 Allen Bit for fill and drain plugs (may differ for M18 thread boxes, so have a set ready)
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Thread gauge (such as the one below - https://www.screwfix.com/p/turbogold-plastic-screw-gauge/7337j) or ruler
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Pair of palm gloves (wear https://www.toolstation.com/palm-gloves/p64335 these, they'll save your hands)
Latex gloves
Eye protection
Brake cleaner
Wire brush
Wire Wool
Oil Drain pan
Mini oil fill pump https://www.sealey.co.uk/product/563720353...-mini-pump
Degreaser/White spirit
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Steps Involved:
Step 1: Raise and secure the vehicle (15 mins)
Ramp the vehicle, put in off-road height, and place axle stands beneath the front and rear subframes on the left side of the vehicle (the transfer box is centre-left).
Step 2: Clean around the fill and drain plugs (2 mins)
You don't want any rust or dirt making its way inside your transfer box, so clean the surfaces around them with the wire brush and wire wool. This will also aid releasing the plugs.
You can clearly see the drain plug on the bottom of the transfer box, and the fill plug on the side.
Step 3: Loosen the fill and drain plugs (5 mins)
The transfer box plugs are easily accessible. The drain plug is on the bottom of the transfer box. The fill plug is on the side of the transfer box.
First loosen the FILL plug. If you cannot remove the fill plug, you won't be able to fill the transfer box with new oil and should therefore stop and book the car into a garage.
Unlike the differentials, the transfer case is stainless steel, so your fill and drain plugs should crack free relatively easily, and with no more than a small ratchet.
Use the small ratchet and H8 bit to first TIGHTEN the bolt by 1/32, then loosen by 1/16. The bolt should crack free (the slight tighten first helps aid releasing the threads).
Once the plug can be loosened by hand, stop.
Now it's time to loosen the drain plug. Have an oil pan underneath in case of any escaping fluid. Use the small ratchet and H8 bit to first TIGHTEN the bolt by 1/32, then loosen by 1/16. Once loosened, position the relevant drain pan or funnel underneath.
Step 4: Drain the transfer box (5 mins)
Now put on a plastic glove and gently unscrew the drain plug to drain the oil.
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Now remove the fill plug.
My waste oil was a similar colour and smell to the new oil going in, despite not having been changed in my ownership.
Step 5: Clean up the drain and fill plugs and measure (5 mins)
The plugs will have old oil on. Give the plugs a good degrease in some brake cleaner.
Be sure to collect and clean the metal washer. If it is not on your bolt, check it's not stuck to the transfer case.
There are different specifications of transfer case bolts and torques for petrols and diesels and model year, namely an M16 or an M18 bolt (your vehicle will have a matching pair). Most vehicles have the M16 plugs. You will need to know which one you have for later, and also if you need a new washer due to damage/it being missing. The below image shows the bolts and what the washers look like.
You can see in my gauge that my transfer box has the M16 type bolt. If you do not have a gauge, you can use a ruler to measure the diameter of your plugs.
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If you require replacement parts:
IYF500030 - M16 drain/fill washer
IYB500020 - M16 drain/fill plug
Step 6: Re-fit the Drain plug (2 mins)
The plugs are stainless and unlikely to seize (unlike the diff plugs), so using anti-seize is entirely optional. Good practice would be to lightly coat the threads and washers in some new transfer case fluid to help ensure a good seal.
Screw in the drain plug as far as you can by hand. Use the torque wrench with the H8 bit to tighten the drain plug to the following specifications (and as in the specifications chart above):
M16 plug: 22Nm
M18 plug: 28Nm
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Step 7: Fill the transfer box (10 mins)
Use the correct fluid and quantity.
Hook the fill hose from your fill bottle into the fill hole and pump in 1.5L of TF 0753 fluid. This will take a number of pumps, so switch arms once tired. I recommend filling 1.6L in the pump, as some oil will remain in the bottom of the pump and in the hose.
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Warning! Do NOT fill the transfer box until you begin getting drips from the fill hole. This is not the correct method and will result in your transfer box being over-filled. The workshop manual states to be level with the bottom of the fill hole. Filling with the specified quantity of 1.5L should achieve this, as stated in the specifications.
Step 8: Re-fit the fill plug (2 mins)
Screw in the fill plug as far as you can by hand. Use the torque wrench with the H8 bit to tighten the drain plug to the following specifications (and as in the specifications chart above):
M16 plug: 22Nm
M18 plug: 28Nm
Step 9: Clean Up (5 mins)
Now clean around the fill plugs with some cloth or paper towel, and douse the transfer box with brake fluid to remove any residue. Wipe any remaining residue from the bottom of the transfer box
You are done!
It's also time to clean up the mini oil fill pump. Pour some degreaser or white spirit inside the pump and pump through the fluid, plus give the unit a shake (whilst blocking the breather hole) to give it a good clean. Now leave the top off and allow to dry. Blow through the pick-up point of the pump to flush through any remaining fluid.
You will notice my transfer box has a smear of old oil from a previous leak which hadn't been cleaned up (i inspected and couldn't find any source of a leak), so i also mixed up some degreaser and gave the transfer box a good clean. This took me an additional 10 minutes:
2015 Range Rover Autobiography 4.4 SDV8
Last edited by garyRR on 27th Feb 2024 6:59am. Edited 3 times in total
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29th Jun 2023 10:02am
