Hi I am in a bit of a pickle (aren't I always).
Currently have my right hand side wheel jacked up this happens on the other wheel too I think but when I start the car and put it on reverse and let go of the clutch when the engine is idling as the axle starts to spin there is a bad rumbling and clanking noise, I cant quite tell if its in the differential.
It must be, but, as I rev the engine and when the axle spins faster the noise goes off I have the back cover of the differential off and the brake disk off.

I remember when the car was on the ground and if you would keep reversing backwards there would be a noise like something is getting jammed and jumping inside along with the clanks and rumbling this mostly happens on idle I think and on the 3rd gear as well i cant see anything getting jammed or anything i don't thing the propeller shaft is hitting anything and it cant be the gear box although the car is temporally converted to a manual.

Any ideas bad bearings the CV joints look good but i am no expert probably the drive pinion etc all feed back will help a lot,

The car is a 1975 240D W115 2nd version.

Thanks Jeremy.

Uh, it's never happened to me on a mercedes, but if the cv joints are bad in the axles, they should wiggle when you yank on them up and down or forward and backwards. Put the car on a railroad tie before getting under it and pulling on it. If wheel bearings are bad, the wheel should wiggle in and out at the edge of the tire. When the pinion and ring on my ford 9" rear end finally wore out at 300000 miles, the car shuddered to a halt going grunchagrunchagruncha, you could feel the teeth hitting. My mercedes 240d rear end is high milage and loose, with the wheels on the ground the prop shaft will wiggle 1/2", I'm rebuilding it before I go out of state again. I took it to colorado right after I bought it and the cheapo motor overhaul, when it would misfire above 6000 feet the car would shudder forward and back due to the loose differential.

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'80 240D biege "Mercey Bird"
'80 240D light blue "Slug"
'80 300SD dark blue "Theodin"

ok maybe i'll take a look at the dif cant quite seem to think of anywhere else
the noise is coming from thanks jeremy

Most likely bad cv joints. The diffs are darned near indestructible.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Do as you did to hear the noise with car jacked up but listen with a Mechanics Stethoscope (cheap at Harbor Freight) or my favorite a 3-4 foot piece of wooden Broom Stick press against the suspected area on one end and my Ear on the other. (I prefer the stick as it is longer and keeps my hear/face further away from the suspected site and I find the Stethoscopes (I have 2 of them somewhere) to be too loud and anthing the Stethoscope tubing touches or bumps also conducts sound.)
Caution;keep your head away from the moving Wheel and the Exhaust pipe.

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84 300D, 82 Volvo 244Gl Diesel

is it possible that the taped roller bearings in the axle of the wheel is bad when the wheel turns faster the noise disappears, there is something else i have the differential removed and i am thinking of filling new sae 90 oil and greasing the cv joints with cv joint grease and lastly the cv joint.
Now there are 2 ends, and the end that goes onto the spider in the differential moves quite well up down left right and so on not to the extent that it shakes in there and has a play, but the end that goes to the axle now that is very tight and almost impossible to move does'nt mean it wont, but its far more tighter that the end that goes to the differential, harder to bend is this normal?
thanks Jeremy

The cv joint should bend, and should slide in and out a little but not have any free play up and down. If it has up and down play its bad. The actual bearings hardly ever fail either, usually its the cv joint.

They will sometimes lock up but if they are loose it will be off center and set up a hopping in the back end, but when you back up there might be grinding or clunking. If you have any of these things total failure is staring you in the face.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

thanks for that the joints on the top are a little loose than the ones at the bottom that go to the wheels right now i have a broken rubber boot and don't know how to get the old none out to put the new one in cant figure out how to remove the joint to put the rubber boot through

thanks jeremy

You can use a greased funnel to shove the boot over the joint without removing it.

i have the stock mb boots not the flex kind or what ever they seem pretty hard wonder if they would expand so much without braking

One of the Members said he used a Grease Gun with a Needle Attachment that they sell. Pierced the Boot and injected the Grease.
I for get what he patched the hole with but I believe if you wiped down the area with Brake Cleaner and a Clean Rag that a dab of Silicone Sealant on the out side would seal the Needle hole.

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84 300D, 82 Volvo 244Gl Diesel

It does not sound like grease will help. Did you check for looseness in your half shaft?

Grinding and clunking means the damage is already done.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

sorry for the late posts i managed to put new cv boots its really easy when you remove the cv joint end then its just a matter of pulling the old one out and pushing in the new one all you need is a hammer and a small pice of plywood. i put in the differential and its not the differential or cv joints the taped roller bearings ect are all good so i just filled new sae 90 oil and put it back in and the noise still continued so i removed the propeller shaft and and checked the universal joint and the bearing that goes for the bracket that holds the propeller shaft where the short one and long one joins and its good too so i don't know what to do now the noise comes somewhere from there. There is something else with broth propeller shafts removed i started the car and put it on reverse and let go of the clutch just to see if it was from the gear box and there was no noise its not from the gear box so ...... i dont know what else to check but it comes from near the bearing of the propeller shaft now the noise however comes when the wheels are turning the slowest and i think thats reverse on idle it would come if you put it on the first too but while its on the reverse and if you accelerate the car abit the noise would go off so i mainly hear this when reversing on idle


ps the automatic gearbox that came with this car had to be removed due to mechanical problems and was replace with a w123 manual gear box and the length of the small propeller shaft was reduced to fit the manual gearbox my father says it wasn't very professional work in srilanka could this be the reason ?
please help

thanks jeremy clarkson himself