Manual transmission/Differential fluid change: how difficult?
 

My mechanical background for car-related work is limited to just one engine oil change, which I performed yesterday. Naturally, I wish to avoid opening the proverbial can of worms and ending up with more on my hands that I can handle...
I have a Haynes manual (Diesel 123 Series) which describes very poorly both fluid changes in less than half a page; besides, most of the images shown do not match the items and locations for my specific model (1979 240D). Are there more precise instructions/images I can view online?

I have wooden ramps which will raise my vehicle 4" evenly from the ground and enable me to go underneath to do the work. I would like to know what special tools I need to have in order to perform these fluid changes (special wrenches, pumps, etc.), what type of fluids are preferable for my particular car model and, honestly, are these maintenance tasks within the reach of a beginning DIYer like me?

Thanks in advance,

Rino

It's a pretty easy process. Not sure if I personally would get under a car with wooden ramps:eek: but...I'm sure they're pretty stable right? LOL


Here's an invaluable resource: the dieselgiant.com website


http://dieselgiant.com/mercedestransmissionfluidchange.htm


and that link is for the still pics walkthrough.

you can buy the dvd how to (which i did-and it's good) from that site, too.

good luck!1
:)

That's for an automatic.

Exactly! Does anyone know of any online guides that provide step-by-step instructions (with images) for MANUAL transmission/differential fluid changes on a (1979) 240D?

It would be very much appreciated,

Rino

P.S. I just read somewhere that the Redline MTL fluid is excellent for the manual transmission (it seems to smooth out gear shifting marvelously)... What to use for the differential? Ideas? Comments?

There isn't much easier than the differential and manual transmission fluid changes. They are both about the same. There is a drain plug and a fill plug. They should be a 14mm allen socket. Remove the fill plug first. Then remove the drain plug. Let it drain. Fill it back up until it starts flowing out the fill plug hole. Seal it back up using new washers and that's it.

I don't know for a fact that there are any washers for his car. I think that the torque spec for each plug was 60Nm or 44ft-lbs.

The diff. takes 1.1 quarts of SAE 90W gear oil (I used Mobil1 synth)
The tranny takes 1.7 quarts of type A trans fluid (I used a Redline MT oil)

I've even heard of people using 10w30 in the manual transmission with no ill effects. Personally, I would stick the type A or a manual trans fluid. Maybe even gear oil if the bearings are getting noisy, but then you're not too far away from a rebuil anyway.

In addition to the 14mm allen socket, do I need a pump to get the job done?
Are you familiar with pump models that work as they are supposed to and can you suggest them to me and where to find them?
So, no washers available for sealing the drain plugs in my 240D...
Is it safe to perform the changes without using a torque wrench (with just the 14mm allen socket)?
Redline MT or MTL for the tranny? (I read Redline works wonders for manual transmissions...)

I just read a post from someone saying that using ramps under the rear wheels to raise the car, therefore putting it on a slight incline toward the front, is a plus because you will get a few more ounces in the diff than you would if the car was level...
But wouldn't that also keep part of the old differential fluid trapped in and prevent it from being drained completely? How would ramps used under the front wheels affect the manual transmission fluid change? I would very much appreciate your clarifications regarding these points, if possible...

Thank you very much for your advice.

At the EZ Lube joint I used to take my car to, last year they refilled the tranny with the same oil that was put in its engine... I want to replace that with Redline fluid as soon as possible.

Rino

Use Redline MTL for your tranny. Buy two bottles. You will need only about 1.5 bottles.

Buy one bottle of Mobil 1 synthetic gear oil for your differential.

Buy a hand pump at any auto parts store to transfer the fluid from the container into your car. If its really cold outside, store the gear oil in your house to warm it up a bit so it will flow in much easier.

Always remove the fill plug first.

You can get by without a torque wrench. Just make it tight.

Scott

I used more than 1 qt to fill my rear end. not much more, but enough to warrant purchase of another $10 bottle of Mobil1. you only need to do it every 3-4 yrs.

as stated, remove fill plug first. this way you will be assured that you can fill it,sometimes people have drained the fluid, only to have the fill plug stuck!

the 14mm allen socket can be had at most autozones in a 3 pc set for $10.

I also spent $7 a while ago on a grease suction gun. it is like a grease gun, but woith a 3/8 tube on the end that you can suck grease into, and then push it into your gear box. helps alot for hard to reach fill holes, such as a 123 wagon diff. or get one of the hand pumps. slower, more likely to break if stepped on, more $$. but they sure beat using a turkey baster!

[quote=rino;1423760]

I have wooden ramps which will raise my vehicle 4" evenly from the ground and enable me to go underneath to do the work. If you can get vehicle level somehow, floor jack, and jack stands are a worthwhile addition to your "tool box", if you will be routinely working under car.

Thank you all guys for your advice!
So it will be Redline MT or MTL for the manual tranny and Mobil 1 synthetic gear oil for the differential.
Before heading for my local autozone/pep boys stores, I need a quick question answered... I read about folks having problems unbolting the manual transmission plugs when using the common L-shaped 14mm hex (Allen) wrenches sold in stores, apparently because of the tight space in those areas... what gives? Should I get an L-shaped hex wrench, or is a hex socket preferable, or what?

Also, do the tranny and differential need to be hot for doing the fluid changes optimally? How long to drive the car before performing those procedures?

Thanks a lot...

Rino

Get the MTL.

It is a tight fit. I used a socket but I could not attach the ratchet because the space was too tight. I inserted the socket and used a wrench to turn the socket.

You want it to be hot. Take it for a short spin.

Good luck.

Scott

Be careful doing the differential
 

The rear differential on my car has 2 openings from what I remember, one to fill, one to drain. You want to loosen the TOP one first, because if you open the lower one to drain first, then find you can't get the fill one open, you're screwed.

jeff 1991 300d

Mission accomplished: did the differential fluid change this afternoon with Mobil 1 75W90 synthetic gear lubricant (it took about 1.3 bottles to fill). Both plugs were tough to open and I was glad I had with me an 18-inch length of steel pipe that I used for leverage, without which no way I could have open them... I used the 14mm hex tip socket (with a ratchet) from Autozone.
Next in line is the tranny fluid change, which I'll do either tomorrow or day after with Redline MTL (got two bottles today). I hope that inserting the hex tip socket then working it with a wrench, as suggested by Scott, will work. The other option is to use a metric bolt with two nuts tightened snugly (got the idea from an old post in this forum) which, combined with a 14mm wrench, simulates the dimensions of the MB bent wrench that came originally with the car (not in my case). I got both bolt and nuts today, however though the nuts are the correct dimension (14mm), the bolt is 14.1 or 14.2mm, and I'll need to file it down to 14mm in case the hex tip socket/wrench combo doesn't perform as expected...

Thanks guys for all the advice... which made changing the differential fluid today much easier than I had expected!

Rino

I checked under my car, and was surprised to see that there's plenty of room near the transmission fill plug for both the 14mm hex tip socket AND the ratchet... (I don't understand all that fuss about tight space that called for the special MB tool - or am I missing something here?)
So, the transmission fluid change is also going to be a piece of cake!

QUESTION: Does the suction pump need to be thoroughly cleaned or it doesn't matter if some of the Mobile 1 gear lubricant I used for the differential gets into the Redline fluid I'm going to put into the transmission? What's a good way to clean inside the pump and its tubing?

Rino