|
|
|
#1
|
||||
|
||||
w123 highway clunking driving me nuts
After about an hour of highway speed driving there is an erratic clunking underneath the car towards the rear. Initially I thought it was the exhaust clanking around, but I removed the exhaust and it's still happening.
I've read that this is often the rear CV axles. Mine look good, boots are solid. Could still be the issue but wanted some feedback here. It sounds like someone whacking the underside of the car with a mallet. Only when fuel is applied, not when coasting. It's also not exactly rhythmic, random in intensity.
__________________
1984 300CD |
#2
|
|||
|
|||
Check your rear flex disc and the mounting bolts.
Also check your exhaust heat shield mounting bolt(s).
__________________
78 W116 300SD 'Desert Rose' new as of 01/26/2014 79 W116 300SD 'Stormcloud' RIP 04/11/2022 Last edited by Alec300SD; 09-23-2016 at 01:08 PM. Reason: typo |
#3
|
||||
|
||||
While looking at the flex discs look at the drive shaft support.
Is the clunking when you are driving straight or does it only happen when you go over bumps? Does it clunk when you accelerate from a stop? There is a large drive shaft coupling nut. See if that is loose.
__________________
84 300D, 82 Volvo 244Gl Diesel |
#4
|
|||
|
|||
Does it stop even for a little while if you stop and backup for a few yards ?
__________________
1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#5
|
||||
|
||||
Happens going straight, nothing to do with bumps. Wouldn't know about backing up because it happens at highway speed. Does not happen from a stop, only after about an hour of 60+ mph speeds. Sometimes continues for a few minutes after exiting the off ramp, but subsides. I've checked the flex disc, it looks good.
__________________
1984 300CD |
#6
|
|||
|
|||
Low lubricant level in the cv joint is a common cause. The cv joint has to heat up before it is obvious. Add some very heavy oil to each side to see if that is enough before too much damage is done.
Just loosen the inner clamps and feed a tube in through the boot to axle space feeding it with something like a turkey baster. Almost 80 percent certain this is your issue. The longer you drive it like this the higher the odds become of the cv joint being destroyed. The clue is always almost the same. Car has to be driven until the joint components heat up. From the lack of lubrication. Let us know if this solves it. You still stand a good chance as they are not clunking all the time yet. Once they are clunking all the time it is usually too late. The original lubricant was heavy oil. Some use grease but if you have taken apart damaged cv joints you will have noticed the grease has lost the contained lubricant and only the soap filler without the oil is left. Usually well displaced from the area where the lubrication is needed. Straight heavy oil does not do this. |
#7
|
|||
|
|||
Could be just the exhaust hitting the body, which can make a very noticeable sound. My 1984 does that the few times I had two big guys in the back, compressing the springs. Happens mainly at idle. I tried to reproduce it, having my wife stand on the rear bumper as I looked, but couldn't find anything in the exhaust that could touch, so perhaps a worn rubber bushing that allows metal-metal contact under load. The independent rears in these cars is more complicated than the simple solid axle - leaf springs of most 70's U.S. cars.
__________________
1984 & 1985 CA 300D's 1964 & 65 Mopar's - Valiant, Dart, Newport 1996 & 2002 Chrysler minivans |
#8
|
||||
|
||||
As said above, sounds like cv joints, since heat build up is a factor.
I've had good luck using long curved, tapered, all plastic-tipped syringes to apply the gear oil into the boots. I then use hose clamps to seal the small side of the cv boot back up. It probably throws the balance off a bit but I haven't noticed anything undue. Good to get them before they are worn out. switching the cv's left to right to begin a whole new wear pattern isn't a terrible idea as well if you've the time and energy.
__________________
97 e300d, 78 300Dt, 95 E300d, 94 E320 estate |
#9
|
||||
|
||||
If yo don't use the special CV Joint Oil from MB use Differential Oil on the CV Axles (I believe some have used that when they re-boot their axles).
__________________
84 300D, 82 Volvo 244Gl Diesel |
#10
|
|||
|
|||
Since we're on the subject of injecting oil in the boots...
Quote:
__________________
84 300SD 85 380SE 83 528e 95 318ic |
#11
|
|||
|
|||
Diesel911 just gave you the best answer... notice the use of the word ' oil '...
__________________
1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#12
|
||||
|
||||
are these syringes stocked at auto parts stores? how much diff oil should i be putting in?
__________________
1984 300CD |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|