How long can engine mountings last?

[W L Ow]

I have changed the engine mountings of my 1997 C200 w202A exactly 2 years 7 months or 40,000km ago. I changed them because the car vibrates at the bottom of a dive immediately after passing road hump. Changing the mountings solved the vibration problem completely at that time.

Now the car begins to vibrates again especially during acceleration and deceleration. Noticed what looks like a circular crack on the top of the mountings. Could the engine mountings needs changing again?

Thanks in advance.

WL OW

 

[Ian B Walker]

I suspect, looking at your location, that humidity has a lot to do with your problem. That or you have some oil dripping onto them. I recently changed some enginne mounts that had covered some substantial mileage and only because one had been covered in oil for some time.

 

[glojo]

I suspect, looking at your location, that humidity has a lot to do with your problem. That or you have some oil dripping onto them. I recently changed some enginne mounts that had covered some substantial mileage and only because one had been covered in oil for some time.

Hi Ian,
I am way out of my depth here, but I can remember the old Singapore Mercedes taxi's that had covered hundreds of thousands of miles if not perhaps millions??? without any great problems. Could this problem be an alignment one? I'm thinking perhaps accident damage?

John the inquisitive

 

[Ian B Walker]

Hi Ian,
I am way out of my depth here, but I can remember the old Singapore Mercedes taxi's that had covered hundreds of thousands of miles if not perhaps millions??? without any great problems. Could this problem be an alignment one? I'm thinking perhaps accident damage?

John the inquisitive

Its quite possible John. Lets ask Mr OW when he next comes online

 

[W L Ow]

Dear all,

The car never had a serious accident before and is in good shape. It has to date done 93,000 km mainly home to work-place driving. The last time I changed the engine mountings I did it myself and did not notice any oil deposit on them. However, the rubber portion on the top of the mountings between the outer shell and the centre mounting piece were cracked.

The old mountings were definitely not working when they were last changed because the vibrations were gone immediately after they were changed until recently. Since the last change was done at about 53,000km and the car has done another 40,000km, I would think it is not totally impossible that the mountings have failed again. If mountings are not supposed to fail that often,then there must be explanations.

If the current round of vibration is not caused by the engine mountings, what else could have caused it. I have checked and found the auto transmission fluid to be at the correct level.

Thanks in advance.

W L OW

 

[glojo]

Dear all,

The car never had a serious accident before and is in good shape. It has to date done 93,000 km mainly home to work-place driving.

Hi W L Ow,
Ian is a very knowledgeable person whose opinions I hold in very high regard however I simply believe there is a mechanical reason for your problems. If it was climate, then there would be queues outside the various garages in your beautiful country.

Something is causing this premature wear, be it misalignment, vibration, wrong parts etc??

Or... it could be just what Ian has suggested.

Has your car got any oil leaks that are flowing onto the mounts?


Good luck,
John

 

[Uberwagon]

Rubber mounts have a really hard life if they aren't fitted correctly.

They need to be fitted with no tension on them, then with the back plates oiled slightly (Presuming they are metal backplates to the mounts?) and then the full weight of the engine sat on them before tightening.

When this isn't possible then support the engine so there is as little load on the mount as possible before tightening, even slightly out of alignment can put huge stress on the rubber.

Also, did you replace it with a genuine OE rubber?

Dave!

 

[W L Ow]

Hi Glojo / Uberwagon,

There is no oil stains on the mountings (and the old ones too when they were changed the last time). I have opened the steel cover covering the right side mounting over the weekend to examine the mounting to check whether it is stained with oil .

I think Uberwagon's deductions may be the reason in my case. The mountings are designed strictly for up and down movements. Any horizontal movement will put stress on the rubber part of the mounting and its internal parts whatever they are. However, I recall when I changed the mounting the last time, I have taken precausion to shake the mountings a bit after they were seated in their mounting positions and the bolts installed but before tightening them to ensure that the mounting are in the natural optimum position. It is like golfers waggling their grip during set up. Furthermore, the mountings bolts could be inserted without any force which indicated that alignments was not a problem.

However, it is possible that some other mounting points along the drive train perhaps further back could be loose causing alignment to shift putting stress on the mountings during acceleration, deceleration or up and down motion of the car. Does my extrapolation of Uberwagon's deduction make any sense? If this is the case, where are "THE OTHER" possible mounting points that could shift? Could any one help?

Thanks in advance

W L OW

 

[Uberwagon]

Might be worth checking the gearbox mounts?

Dave!

 

[W L Ow]

Now that you mention gearbox mounts, it reminds me that I have been hearing for sometimes now a single dull knock coming from somewhere below the driver seat whenever I accelerates or brakes hard. I have dismissed it as the nuts holding the driver seat has come loose.
I will certainly take a look at the transmission support bracket this weekend.

Thanks

Ow