ML 270 Vibration

[John E]

Hello everyone, please bear with me as I am new to this forum and to MB ownership. After many years of Discovery ownership I was a bit disappointed with the general condition of the examples on sale when I came to change this time, so i took the plunge and bought a 2001 ML 270 with lux and family packs. All in all I'm pleased with the vehicle apart from it's developed a vibration. I'll try and describe the best I can -

The vibration is only light, it is definitely worse when the car is cold it almost disappears when it warms up. It seems to be drive-line related as it doesn't vibrate when you're parked.
When I leave home on a morning I drive over a few sets of speed humps, when the suspension dips/bottoms after gong over a hump the vibration momentarily stops until the car levels again.

I'm beginning to think along engine mount lines, or are there any other common faults I should know about

Also are there any good online parts suppliers you can recommend.

Thanks in advance for your help.

 

[oigle]

The fact that the vibration decreases when hot versus cold would seem to point to tyres as they are one of the few things in the driveline that alter when hot. Maybe balance or a flatspot in a tyre/tyres. Have you tried higher pressure? Would be a pointer. Tyres can flatspot a little more overnight with lower pressures.
For other problems, check my website for my faults and fixes. Not much use to you outside of Australia I know, but at least it identifies some inherent problems.

http://members.optusnet.com.au/iananddesley/

 

[John E]

Thanks, but the tyres were getting worn, so I have replaced all four and still no better

 

[oigle]

At one stage, around 20000km, I had excessive engine harshness problems which were worse when cold. These were diagnosed by MB dealer as engine mounts going hard. They were replaced under warranty and that reduced - didn't eliminate - the vibrations etc. Don't know how that could be related to going over speed bumps though. That points to suspension geometry - cv joints etc.
If you select a lower gear and thus keep the engine revs above about 2300, does it go away? This would be a pointer to whether it is engine related or otherwise. The worst vibration point in these engines seems to be between about 1800 and 2200 - right on max torque!!
:smile:

 

[jberks]

I find my 270 to be ok above 2000rpm. I have a resonance at 1100rpm (pretty much exactly) that comes through the whole car. I might get them to look at the engine mounts at the next service.

 

[John E]

Don't know how that could be related to going over speed bumps though. That points to suspension geometry - cv joints etc.

The only way I thought it may possibly relate to it, is as the car drops down on suspension more weight is temporarily put on to the engine mounts

 

[oigle]

Just had my engine mounts replaced again at 40000km!!! Under warranty too!!! Vibration and harshness were intruding again. New mounts did a better job this time - really quietened it down. Perhaps they have a modified mount now. Didn't ask.
Service advisor said mounts sag, mainly on drivers side from torque input, and then go hard. Towing, which I do, makes it worse. Unless these mounts last better, looks like I'll be paying for the next lot!!
Just telling you this to reinforce the message re mounts DO cause lots of vibration/harshness problems. Why don't you replace them and see if your problem goes away. Your thoughts on weight transference on bumps could have relevance, if they are really shot.

 

[RedD]

Finally got round to changing the mounts today (they've been on the garage shelf for a month)

Wow....... What a difference , it's like a new car.

Worn engine mounts certainly do cause vibration:roll:

 

[oigle]

Great!!! Glad I could be of help.

 

[jberks]

You guys all on MLs? Anyone know if the same issue affects E270s ? Its not too bad, but many people describe it as extremely smooth and to me it doesn't fit that description under acceleration.