W211 E320 CDI OM648 rattle/vibration (video)

[jeremy156]

I wonder if anyone is able to determine from a video clip what might be wrong with my car.

There is a lot of vibration in the engine which leads to the air filter enclosure and the intake hose to resonate. I have made a big improvement to the noise by taping up the join between the hose and the box as you'll see with gaffa tape and some draught excluder strip to take up the gap, yet there is still a distinctive low frequency buzz/boom from the engine. Sometimes it's quiet (as per the fisrt half of this video) and other times it'll be intrusive even when driving with wind and tyre noise.

After I rev the engine in the video clip you can see the hose and filter housing vibrating quite clearly. I can't figure out how the box itself it attached to the engine, whether a bush or grommet needs replacing perhaps. I'm inclined to assume something is wrong to cause such vibration and that changing the engine mounts would simply be to mask the problem - any opinions?

http://www.youtube.com/watch?v=4uCzgS5ObE0

 

[Matt's Dad]

I’ve been trying to figure out how to remove the air filter housing on my E320 CDI, and it looks like the housing is held inplace either end, by short plastic shafts that go into rubber bushings. I might be totally wrong, but you may have lost the round bushes, so the plastic shafts could be vibrating on the metal fixings?

Also, I couldn’t believe the difference to my whole car, after I changed the engine mounts. My car has covered 175,00 miles, and is now much smoother and quieter than my Range Rover Vogue, with a lot less miles on!

 

[jeremy156]

I'll see whether I can prise it apart and check the condition of the bushes that hold the airbox in place, it would make sense if they're no longer absorbing the vibration that this would exaggerate the noise.

When you had your engine mounts changed, what made you decide to go ahead? Were the mounts visibly leaking? Was the engine vibration particularly bad? In my case they don't appear to be leaking (looking from the top), but if I rest my head against the side window (think traffic jam, bored) then my skull buzzes against the glass

 

[BlackC55]

It will be the airbox bushes that are worn. Cheap and simple to fit.

 

[jeremy156]

Right, I've ordered a set of new bushes to be delivered early next week. Is it relatively intuitive to remove these once I get the filter out? I presume they're held in by friction as I couldn't see any bolts when exploring recently.

 

[Matt's Dad]

When you had your engine mounts changed, what made you decide to go ahead? Were the mounts visibly leaking? Was the engine vibration particularly bad? In my case they don't appear to be leaking (looking from the top), but if I rest my head against the side window (think traffic jam, bored) then my skull buzzes against the glass

I had only just bought the car and at tickover it had a vibration, aswell as when pulling away, and there was a nock when I turned the engine off.

There wasn't any obvious signs that they had gone - until I compared the old ones to the new ones, the new ones were much taller. Have a look for pictures on this site, and you see what the new ones should look like.

It will be the airbox bushes that are worn. Cheap and simple to fit.

Is there an easy way to remove the airbox? I couldn't see any bolts fixing it to anything?

 

[jeremy156]

Airbox filter housing instructions

I've just found a workshop instruction document explaining the removal and fitting procedure for the air filter housing. I can't upload to this forum as the PDF is over 100kB in size (site limit). PM with an email address and I'll send it over to you.

 

[jeremy156]

OK, I changed the bushes last night, reasonably straightforward.

Instructions:

1. Remove engine cover
2. Disconnect the two electrical connectors at the front.
3. Detach the air intake hose.
4. Loosen the screw on the metal strap and detach the hose, leaving the MAF attached to the filter housing box.
5. Holding the hoses and cables out of the way, lift the front of the box, it'll be stiff but you're lifting the existing rubber bungs from the frame.
6. Once the front is out, you can pull the whole thing forward to remove the rear bungs.
7. Pull the old bungs and replace with the new ones - I applied some grease to help things go back in place easily.
8. Everything back together

 

[ca-uk]

did it solve your problem?

 

[jeremy156]

Yes, it's dampened down the "buzz" and resonation at idle. Still lots of engine vibration, just no longer shaking the air filter housing as dramatically as it was.

New engine mounts next week - will feed back any improvement from that.

 

[Matt's Dad]

OK, I changed the bushes last night, reasonably straightforward.


Instructions:

1. Remove engine cover
2. Disconnect the two electrical connectors at the front.
3. Detach the air intake hose.
4. Loosen the screw on the metal strap and detach the hose, leaving the MAF attached to the filter housing box.
5. Holding the hoses and cables out of the way, lift the front of the box, it'll be stiff but you're lifting the existing rubber bungs from the frame.
6. Once the front is out, you can pull the whole thing forward to remove the rear bungs.
7. Pull the old bungs and replace with the new ones - I applied some grease to help things go back in place easily.
8. Everything back together

Thanks for the instructions I'd missed your thread about PM

The engine mounts were fairly easy to change, but I do have use of an open pit. There was a "HOWTO" I followed for a W210, and it seemed fairly similar, apart from I did everything from underneath (the instructions say to undo the top bolts from the engine bay, I found it much easier from under the car)

 

[jeremy156]

OK, engine mounts changed and what a revelation! With these two jobs done (air box bearings and engine mounts) the engine is now as quiet as I'd ever hope for a big diesel to be, it has totally transformed the car. No longer a "clunk" as the car twists coming off the driveway, the wild shake when cutting the ignition is now a modest wriggle and best of all the growling gnarling noises as gentle throttle are gone - now the only time I really hear the engine is under heavy throttle, just as it should be.

Happy

 

[ca-uk]

Could you do us a video for comparison?

 

[jeremy156]

Sure: YouTube - Mercedes-Benz E320 CDI OM648 engine rattle - improved

Main benefit is how the engine is better isolated from the chassis and therefore the noise inside the car is reduced.

 

[ca-uk]

Thanks - not got speakers on at moment but will listen to night

 

[jeremy156]

Bear in mind the engine noise itself is pretty much as before, the difference is in the additional resonating parts causing the deep buzzing and of course how it transmits to the rest of the body - the new more flexible mounts are absorbing a lot more.

 

[142 TPL]

I had a lot of simular issues with my 270CDI it turned out to be the alternator pulley. It has a clutch in it that is known to seize and make the engine vibrate at idle

 

[142 TPL]

Check out YouTube alternator pulley comparsion
and you will see why

 

[fred_raven]

vibration when idle

i have a similar problem, a quite loud judder/ vibration at idle. bit of a clunk when ignition is turned off otherwise car drives fine. had engine mounts changed about 6 months ago so wouldnt have thought that can be the problem, unless they are faulty , or did wonder if wrong ones could have been fitted ( e220 instead of e320). i have tried to remove the airbox to check the bushes but cant get the front to lift , how hard does it need to be pulled? any suggestions what else it may be?

 

[delb0y]

same problem here, not sure what it is but initially thought it was one of the injectors. I have noticed my airbox isn't completely closed due to the clips being broken, the MB dealers wanted me to buy the whole airbox and wouldn't sell just the clips/bushes?!

anyone know if these parts can be bought elsewhere?

cheers