When engine mounts get really bad could it cause this? - PeachParts Mercedes-Benz Forum

benedict · #1 12-07-2011, 05:09 AM

Hi all,

My engine mounts are on the way out as I noticed engine vibration a few months back. Also the clutch fan is sitting lower in the fan shroud - possibly dropped 10mm or so and the fan has even begun rubbing on the bottom of the fan shroud.

New mounts are on order and I will change them out this weekend, providing I can crack the 17mm bolts, I have already tried- they are in really tight!

A new issue has risen in the past few days. When I engage reverse, it goes in no problem but when I begin to drive in reverse (slow or fast) it is making a grounding noise, as if it isn't engaging correctly or something is misaligned.

Could it be possible that my engine/transmission has dropped so much that they no longer align up correctly to the drive shaft?

Transmission fluid and filter is clean (changed 30k ago) and fluid levels are good. Drives absolutely perfect in forward.

Any suggestions are appreciated.Thanks

t walgamuth · #2 12-07-2011, 05:54 AM

Yes. Your guibo might be rubbing on the floor pan or something similar.

If it does not go away with new mounts, then is the time to worry. And in the mean time just don't use reverse any more than you have to!

vstech · #3 12-07-2011, 08:21 AM

for that bolt, I had to buy a more powerful impact wrench... I got lucky and found one on clearance at harbor freight.
the noise could be lots of things, keep in mind if the mounts are totally shot, the motor will be twisting in the bay causing all kinds of things to bind... don't drive until you've changed them.
you could also have a really rotten rear transmission mount, or even a flex disk failure...
get under your car and REALLY look everything over!

benedict · #4 12-07-2011, 03:45 PM

Quote:

Originally Posted by vstech

for that bolt, I had to buy a more powerful impact wrench... I got lucky and found one on clearance at harbor freight.
the noise could be lots of things, keep in mind if the mounts are totally shot, the motor will be twisting in the bay causing all kinds of things to bind... don't drive until you've changed them.
you could also have a really rotten rear transmission mount, or even a flex disk failure...
get under your car and REALLY look everything over!

Could a bad flex disk cause the grinding gear?

With the bolt, I had a look on harbor freight but could only see two things that maybe of use, either a crowfoot socket or an s type wrench.
The exhaust manifold is only an inch or so above it so I can't get a normal 17mm socket with uni joint in there. I purchased a stubbie combination spanner but it's in too hard a place to get any weight behind it.

layback40 · #5 12-07-2011, 05:42 PM

Its probably the left mount that is shot. Because of the direction of rotation, under deceleration or in reverse the mount is compressed. When the rubber is gone its metal on metal & it sounds horrible. Under acceleration the motor lifts on the left mount.
The left mount is more likely to fail because of the fuel system being on that side. Mounts dont like a wash in diesel, the rubber soon degrades & fails.
I would do the left mount first & see if there is an improvement.

Good Luck

benedict · #6 12-07-2011, 08:49 PM

The noisy is definately coming from the transmission and sounds like a gear is misaligned. I'll try and record the sound a bit later today.

If you try to put a manual in gear without the clutch it makes the same sound that I am getting and the faster I go in reverse the louder/faster it becomes. I can also hear the noise travelling back up the gear shift leaver.

At a closer look at the clutch fan blade when the engine is off, the end of the (plastic) fan blades are chewing down because the engine has dropped so much and within a short space of time.

Definately become an urgent job now. Not sure how I am going to tackle the 17mm bolt for the right side mount, please see pictures above. I just can't get a socket in there to go square on the bolt head because of the exhaust manifold.