How to "pump" lub into the differential
 

I plan to change the oil the differential. What's the best way of getting the new oil in. I understand some kind of pump is needed.

High thee thence to thy nearest auto parts store
 

and you will find a gadget which looks just like a traditional cartridge grease gun, except that it has no side handle as used to pump grease, but only the t-handle at the bottom, and instead of a grease tube with fitting adaptor at the top, there will just be a plastic tube, often transparent.

You stick the top tube in your can of gear lube (or whatever you mean to transfer from one container to another) and then pull the bottom handle out gradually, which fills the body of the tool with the lube. Then you remove the tube from the can and discover that you are spilling lube all over the floor or driveway from what is dripping off the tube and you grab a rag and wipe it off. Then you go to your differential or transmission (or whatever), which presumably you already had unplugged or else you're in for some more spillage while you set down the tool to get a wrench, and stick the tube into the filler hole (get your mind out of the gutter!) and then push the handle in to inject the lube into the differential. A few seconds later, you will be rushing to wipe up more spillage as the overfill comes rushing back out the filler hole (this delay must be some demonic trap!).

Then you draw off the excess with the same tool, plug up the gearbox or differential, squirt the excess back into the container, providing you didn't let the slightest bit of dirt get on the tool, and clean up everything, which may take a while the first few times until you get the hang of it.

Be sure that you always keep the tube on the tool spotlessly clean, inside and out, or you will be injecting grime into your rear end -- I mean, differential. It is especially frustrating to be under the car, almost ready to squirt the lube in, and then have the tube hit the bottom of the car chassis in some grimy place as you move around toward the target -- the only reasonable thing at this point is to crawl back out and clean everything again.

There are, however, more expensive tools which make some of this a bit easier. Should I have said that first?

Go get a small 1 or 2 gallon garden sprayer and put a 1/4" ball valve on the hose end.
I put a 2" pipe nipple and elbow on that so it hangs in the hole.
When it starts to drip at the fill hole , turn off the valve.
Can find one at the dump as it is usually tossed cuz the sprayer is broke/plugged. But you don't need that part of it anyway.....

Buy turkey baster ($1.99)
Heat and bend (shorten), put aquarium tubing on if you want . Suck up the oil, insert, squirt.

you all sure like doing things the hard way. Buy a lube oil pump from your local automotive shop. they look like big liquid hand soap pumps that fit inside the bottle and pump thru a small tube into the differential. usually takes 20-30 pumps to empty a quart container. I paid $5 for this device about a year ago and have used it nearly daily with no problems.

go to www.griotsgarage.com

check out item number 44406 siphon pump

you can probably find cheaper ones

that's what I use for my rear diff oil changes

be sure to remove the fill hole bolt first before removing the drain bolt.

I found the actual MB tool for the diff bolts a worthwhile investment

5 or 6 ft. stretch of heater hose - place small plastic tube in one end - secure with hose clamp - this end goes into the differential - on the other end is a funnel inserted into the hose - you pour gear oil into the funnel.

The hose is routed down into the differential, then up and over the top of the right rear tire. Alot cheaper than special pump equipment.

Thanks for all the fun reading. Just goes to prove that MB owners are an inventive bunch.

Keep in mind youll need a large allen wrench to change it. My 300D used a 14mm allen socket. Always remove the fill plug before the drain. why? it sucks getting stuck with a differential thats fully drained and you realizing the fill plug is frozen solid. its happened to me before.. and it really ruined the atmosphere for an hour until I got it out. (it took alot of cussing to finally get it to come out)

Learn from my mistake. fill plug first out, then drain!

Thanks. . . I'll definitely removel the fill plug first.