Engine Shocks and Such - PeachParts Mercedes-Benz Forum

sailor15015 · #1 03-23-2006, 05:34 PM

Ok. First off I did a search about this and I couldn't find anything pertaining to my particular problem. In mid February I replaced my engine mounts while chasing down an annoying vibrating noise I have that occurs around 3k rpm, regardless of speed. Anyway so I replaced the mounts, the old ones weren't that bad at all, and the new ones caused the car to shake more. I replaced the rack damper bolt and the big shakes are gone. Now all I have left are the annoying small vibrations, you know, the ones that vibrate up through your foot while you're driving. It also causes vibrating noises in the dash and some side pannels. I tested the driver's side shock while I was replacing the mounts and it seemed stiff. The upper shock mounts also seem to be intact. I have a transmission mount that I bought at the same time as the engine mounts but I have yet to have time to install it. I know that the shocks help with the shakes on shut down(mine shakes quite a lot when I turn it off) but do they have any effect on the smaller, really annoying vibrations? Any help, as always, is greatly appreciated.

Diesel Giant · #2 03-23-2006, 05:43 PM

I have heard of several member replacing what they thought were a good pair of engine shocks and to their amazement, it became a different car. You probably have the originals and they are most likely worn out.

sailor15015 · #3 03-23-2006, 07:01 PM

I thought it might be new shocks but seeing as the shocks, along with the new mounts for them, are a bit pricey, I wanted to get some opinions before I just started throwing $$$ at the problem.

sailor15015 · #4 03-23-2006, 11:51 PM

Ok my plan of attack is to, in this order, install the tranny mount, adjust the valves, then get a tested and balanced set of injectors. If this doesn't work, then I'll shell out the ~$184 for new shocks and mounts. If anyone has any experience on whether or not shocks have any affect on high-pitched vibrations, I'd appreciate your input.

Hit Man X · #5 03-24-2006, 12:42 AM

Trans and motor mounts made a vast difference on my SDL, even with dead motor shocks...

t walgamuth · #6 03-24-2006, 05:29 AM

i dont think i have ever found an injector that was bad enough that changing it did any good.

i have done a lot of them though and have lots of spares.

do the mounts first, imho, then the motor shocks and last do the injectors, but even then test them first. or buy one and rotate it and see if it helps.

also look for things like the exhaust system or air cleaner that is misaligned and vibrating.

tom w

sailor15015 · #7 03-25-2006, 03:46 PM

I'm going to install the new tranny mount tomorrow. My wrecked '85 was as smooth as glass at idle and the mounts are only a couple of years old. I've inspected them really closely in the car and they look good. I think I'm going to get the mounts out of it and see if it makes a difference. I had problems with the air filter mount hitting the metal part on top of the valve cover that holds the bowden cable when in gear. I thought the bracket might have been broken so I took it out and gave it a good once-over and it was fine, no cracks at all. I wedged a piece of wood inbetween the filter and the valve cover. After reading Tom's post I thought that might have been transfering vibrations down through the body. I took the wood out and the vibrations were still there. Thanks for your replies.

Hatterasguy · #8 03-25-2006, 05:26 PM

I don't know about the older cars, but on the SDL with new trans and engine mounts, along with new shocks and shock mount kits she is smooth as glass. You just do not feel any vibrations period, smooth as any late model gas S.

sailor15015 · #9 03-28-2006, 05:54 PM

Ok. I just replaced my transmission mount and while looking for directions on how to do so, I came across this thread. Check out post #6 especially. The reason I bring this up is that, while I was under there, I was able to move the driveshaft up about an inch right above the intermediate bearing. Also I pulled apart some of what I'm guessing is what's left of the rubber. The old tranny mount was good, by the way. It took off a small bit of the lower vibrations but the smaller, high-pitched ones still persist. To recap, I've changed my motor and trans mount and now I'm getting more vibrations than before, mainly high-pitched, extremely annoying vibrations at my feet at around 2800-3500 rpm, irregardless of the speed. What do you guys think about the intermediate bearing support being the culprit since I can move it up and down at least an inch. As always, thanks for your help.

Hatterasguy · #10 03-28-2006, 05:59 PM

With that much play I bet the driveshaft support bearing is worn. The shaft shouldn't move that much.

sailor15015 · #11 03-28-2006, 06:15 PM

Could that be causing the vibrations I'm feeling mostly at my feet? The right foot, closer to the tranny/driveshaft, picks up a lot more vibrations than the left one, the one closer to the door. After typing that I realize it sounds a bit crazy but its what I'm experiencing.

Hatterasguy · #12 03-28-2006, 06:18 PM

Don't know I never had that kind of vibration. Mine vibrated at about 45 and pretty constant. Felt like a very badly balanced rear wheel.

Beach_Benz · #13 04-01-2006, 09:29 AM

Fair warning to everybody; here comes a newbie response. Do Mercedes' drive shafts have weights attached to them for balancing purposes? My Chevy Tahoe had the same problem he is describing and taking the driveshaft to a shop that balances driveshafts cured the problem.

sailor15015 · #14 04-01-2006, 03:38 PM

Could a driveshaft come unbalanced by itself, with out being removed or anything? I ordered a new support bearing mount from fastlane so I should have it fixed by the end of the week.

Hatterasguy · #15 04-01-2006, 05:10 PM

Well their are small weights welded on if my memory serves me. If the universal joint is worn the shaft could come out of balance, I guess. Their would be slop in the joint.

You would need to bring it to a driveshaft shop for balancing and to have a new universal welded on.

Having said that on our cars I don't think this is likely. The diesels don't put out much power and don't stress the driveshaft like the gas engines do. My car in euro spec would have had a 300hp V8 that puts a lot more twist and pressure on the driveshaft then my 603 ever will.

I'd bet on either the trans mount being collapsed(which you changed) so everything isn't alighned, or a bad center support bearing. Or the rubber support that holds the center bearing.

Flex discs don't give you that kind of warning, if it was a flex disc it would have blown apart a long time ago.