I am all for maintenance, but I can honestly say I have never thought of re-greasing CV joints. I would assume that if no moisture or dirt gets into the boot, that grease would be good for life.
I would be more for replacing the boot with the grease, since it appears the boots take a beating first and then introduce dirt into the grease.

 

Guys,

Are some of the old Mercedes CV joints lubricated with the differential oil ? I am not sure but I think I remember seeing this on a 240 D a long while ago. Am I wrong or this thing never existed? If it did exist, did they change the lubrication method on the newer models?

 

I had front CV joint failure on 7 years old 4-Matic with about 80k on it.
There was no damage to the boot and it was full of grease.
Than you see the 35 years old MB with 400k on them and the rear CV joints were never touched. The boots on those work much less, but grease do the exact job.
Bottom line, CV joints don't require any preventive maintenance, but in case of 4-Matic front ones -are subject to premature failure.

 

Thanks for feedback.
Yes i agree. Rear CVs wear at a much slower rate. Also when they are worn they don't show it easily as compared front outer CVs. In my case, i thought my boot was actually stuffed so i tried to clean them but was still not sure if the condition was okay so i opened them up and inspected the inside view of the outside crevice lines. [I had replacement boots ready and was actually going to do the tutorial on the full CV replacement.]
see below:

The one had lost most of its grease (even though the fastening clip was in tact), the other one had too little grease while the other two CVs were okay. At that point i had to re-grease them all. I am from the school where the word check means open and fiddle!
With any maintenance, its difficult to say x miles equals a certain level of wear. Environmental aspects, car type etc are NB too etc. In my case a vehicle with 300k on the clock is common, especially here in Africa.
My CV experience shows me that wear on inner CVs add vibration to the drive (especially on acceleration) and while some people wont notice it others will. Repacking of CVs improves the life of these inner CVs.
While its seems that MB CV layout lasts longer than other cars. Kajtek1, i understand your point, but i would advise inspecting of boots at least. Wagonz, I agree that re-greasing is definitely not critical and for some people not necessary at all.
A mate of mine is foreman of a CV joint and drive shaft re-manufacturing plant. He advise me that CVs have come down in price that serving is not economical as the replacement of the CV is cheap now.
He also advise that repacking improves life time - again inner vs outer, front vs rear drive, tripod vs rzeppa. Also how many people keep a car for longer than 200k?

My view is that while the integrity of the grease may still be good and i am not a specialist on that, minor particles from the joint slowly get added to the grease. These particles reduce the lubricating ability of the grease. Obviously if a boot is broken then this happens much quicker. Changing the grease serves a few purposes, firstly one can assess the boots and joint properly, secondly the wear sediment is removed, the amount of grease present in CV can be checked, and then new grease can be used. Again personal preference. I drive my cars for a long time and servicing of CV has helped get high millage out of them, above 300k while still feeling tight and responsive, again these have been front wheel drive.
Catalind, i am unsure of CV joint for 240D.
FYI: In 2007 we had a batch of grease imported to SA that had not been mixed correctly and CVs were getting worn rapidly. This was the grease that came with the new CVs!

 

I haven't seen any response in regards with the oil lubrication of the CV joint (see post # 3) and I decided to do a little search on my own. I was only partially right. The CV joints on the old W123 were lubricated using gear oil type lubricant. However, the oil was not coming from the differential as I suspected back then ( 15 years ago), which actually makes a whole lot of sense.
As long as the rubber is not affected by the oil chemical components, I believe the oil lubrication of the CV joint must be more efficient than the grease. Safety wise, grease should be safer than oil in case of a boot failure. Maybe this was the reason the lubrication method was changed ( grease versus oil).

 

Even grease will escape via pinhole in the boot.
I used to drive FWD Volkswagen in 4 seasons and had CV joint replaced by shop where they reinstalled old boot. I noticed some grease marks, but in my early automotive years ignored them. The joint didn't last 10,000 miles.
I drive lot of classic vehicles. My bus conversion is 38 years old and I own it for 6 when it was parked for about 10. Since I never replaced oils in the differential and hubs, they have to be at least 18 years old. Maybe original?

 

The reason grease is used in CVs is the grease is made of MoS2 or molybdenum disulfide which can handle extreme pressure properties and high-load bearing capabilities, protects against corrosion, is water resistance, and has excellent oxidation and mechinical stability. I didnt write this, I got it from: McLube MoS2-210 High Concentration Moly Grease

They dont mention it, but I also think that grease sticks to the surfaces more as lube will be flung out as the shaft spins. I dont think regular gear oil can compair.

 

Grease is the oils with some fillers to hold them is semi-solid stage.
Good oil forms "film" on working surfaces that protects and lubricate. The solids are pushed outside.