W221 Airmatic

[V12]

Get MB or an independent to get the car on a ramp and check them.

The rubber in the joints gets old (less supple) and perishes and eventually splits causing too much play in the joint and the suspension is then not working 100% as it was designed to.

I hear that the newest breed of cars has now got to grips with tuning the suspension to deal with RFT, or perhaps the tyre manufacturers have got to grips with making a decent tyre.

Either way, I would find someone with a spare set of wheels with non RFT and swap them to experience the difference before you do anything else.

Even airmatic can't compensate for our useless roads. A few decades ago, tyres weren't just for gripping the road, they also performed an important role alongside the suspension in providing a smooth ride.
Unfortunately with the trend of fuel saving and large diameter wheels for aesthetics, the role of tyres has changed somewhat in car design.

 

[mbenz1]

Get MB or an independent to get the car on a ramp and check them.

The rubber in the joints gets old (less supple) and perishes and eventually splits causing too much play in the joint and the suspension is then not working 100% as it was designed to.

I hear that the newest breed of cars has now got to grips with tuning the suspension to deal with RFT, or perhaps the tyre manufacturers have got to grips with making a decent tyre.

Either way, I would find someone with a spare set of wheels with non RFT and swap them to experience the difference before you do anything else.

Even airmatic can't compensate for our useless roads. A few decades ago, tyres weren't just for gripping the road, they also performed an important role alongside the suspension in providing a smooth ride.
Unfortunately with the trend of fuel saving and large diameter wheels for aesthetics, the role of tyres has changed somewhat in car design.

Thanks for this info. Regarding the tyres, they are low on tread so will be changing them soon. I presume RFT will be expensiver than normal tyres so there is no reason to not buy non-RFT. I almost though RFT were standard on the Airmatic system... thank God for that

 

[ItalianTuneUp]

Hi mbenz1, congratulations on your dad's new W221. Maybe post some pics up here of it?

If you view the second link I posted above, you will see a photo of the top of one airmatic strut. Notice the brass cylindrical attachment that has a narrow air line connected to it? The cracks are where the air can escape. The cracks are in the solid epoxy resin...below this resin (if chopped away), one would find the actual strut seal...iirc, it is some kind of o-ring seal/circular metal spring clip. Epoxy is then used to seal the whole thing up. If one spots cracks in this epoxy, it often means that the struts will leak air.

If you look under the bonnet, to locate the tops of the airmatic struts, look towards the rear of the engine bay, and look for two large circular strut tops, to the left and right of the engine bay. They probably also have three bolt ends visible with nuts tightened on them.

The airmatic valve block can be located on top of the airmatic compressor, and this is just behind the offside headlamp.

I use Continental Sport Contact 5 tyres, and these give a nice cushioned ride quality, IMHO. Continental tyres are originally-supplied tyres on the W220, I don't know about the W221 though.

Once you've some decent tyres fitted, if you're still chasing sources of vibration, then, like V12 says, worn bushes are an obvious place to look. They're rubber bits designed to insulate the body from road vibrations, and when they're worn they lose their ability to damp the vibrations.

Other sources of vibration to check, from personal experience, are engine and gearbox mounts, which damp vibrations from the engine & gearbox. To check these, start engine and put gear in N. If you feel significant vibrations, your engine mounts might be worn. Put gear in D and put foot on brake. If you notice significant vibrations then gearbox mounts might be worn.

Hope this helps. Pics...

 

[mbenz1]

Hi mbenz1, congratulations on your dad's new W221. Maybe post some pics up here of it?

If you view the second link I posted above, you will see a photo of the top of one airmatic strut. Notice the brass cylindrical attachment that has a narrow air line connected to it? The cracks are where the air can escape. The cracks are in the solid epoxy resin...below this resin (if chopped away), one would find the actual strut seal...iirc, it is some kind of o-ring seal/circular metal spring clip. Epoxy is then used to seal the whole thing up. If one spots cracks in this epoxy, it often means that the struts will leak air.

If you look under the bonnet, to locate the tops of the airmatic struts, look towards the rear of the engine bay, and look for two large circular strut tops, to the left and right of the engine bay. They probably also have three bolt ends visible with nuts tightened on them.

The airmatic valve block can be located on top of the airmatic compressor, and this is just behind the offside headlamp.

I use Continental Sport Contact 5 tyres, and these give a nice cushioned ride quality, IMHO. Continental tyres are originally-supplied tyres on the W220, I don't know about the W221 though.

Once you've some decent tyres fitted, if you're still chasing sources of vibration, then, like V12 says, worn bushes are an obvious place to look. They're rubber bits designed to insulate the body from road vibrations, and when they're worn they lose their ability to damp the vibrations.

Other sources of vibration to check, from personal experience, are engine and gearbox mounts, which damp vibrations from the engine & gearbox. To check these, start engine and put gear in N. If you feel significant vibrations, your engine mounts might be worn. Put gear in D and put foot on brake. If you notice significant vibrations then gearbox mounts might be worn.

Hope this helps. Pics...

Thank you very much ItalianTuneUp for the congrats and info. I will have a look at the top struts in the bonnet someday, to see if any cracks are there, just to makesure. Will also check the mounts etc...

I will try to post some pics definately.

 

[ItalianTuneUp]

You're welcome.

If you're buying new tyres soon then I can recommend the tyres I use: continental contact 5 sport. A lovely smooth & quiet ride, good braking in wet and reasonable fuel economy. Anecdotally, I hear that Michelin primacy HP are good too, but that's worth checking out for yourself.

Also, for a smooth ride, inflate the tyres to the correct pressures. When I had my new tyres fitted, I noticed that the fitters had over-inflated the tyres by around 5-10 PSI! Once I dropped the pressures to the correct ones shown inside the fuel filler flap, the ride smoothness returned.

The cheapest place I found for ordering a set of new tyres is TyreLeader. If you order from there, they deliver them to your place, then take them to a decent tyre fitter who can then fit the set and balance the wheels for you.

 

[mbenz1]

You're welcome.

If you're buying new tyres soon then I can recommend the tyres I use: continental contact 5 sport. A lovely smooth & quiet ride, good braking in wet and reasonable fuel economy. Anecdotally, I hear that Michelin primacy HP are good too, but that's worth checking out for yourself.

Also, for a smooth ride, inflate the tyres to the correct pressures. When I had my new tyres fitted, I noticed that the fitters had over-inflated the tyres by around 5-10 PSI! Once I dropped the pressures to the correct ones shown inside the fuel filler flap, the ride smoothness returned.

The cheapest place I found for ordering a set of new tyres is TyreLeader. If you order from there, they deliver them to your place, then take them to a decent tyre fitter who can then fit the set and balance the wheels for you.

Many thanks for your info. Are the continental contact 5 sport run-flats by anychance? Also, does the word 'sport' mean that they influence a sportier ride or does it mean sport in terms of great grip and efficiency?

Yes, I have been planning to check the tyre pressures since the last few days. That will be the first thing on the to-do list.

Would you know what the correct tyre pressures are for the W221 S320 CDI. I have seen the tyre pressure sticker on the fuel cap but that gives pressures according to the number of passengers . The number of passengers in the car varies day in day out lol.

I will keep TyreLeader in mind.

 

[mbenz1]

http://www.mbclub.co.uk/forums/members/mbenz1-albums-mercedes-pictures.html

Pictures. Will try to add some more if possible. Enjoy

 

[ItalianTuneUp]

The tyres are not run-flats. I don't know really but I think the sport may refer to the handling:

"The Continental*Conti Sport Contact 5*delivers an incredibly pleasurable driving experience. Superb grip as well as high performance on a wide range of criteria: shorter braking distance, optimal grip in corners and low rolling resistance."

When you view tyre details on a tyre site, they give 3 specs: noise (dB), wet grip and fuel efficiency. These figures vary depending on things like tyre type variations and the width of the tyre. See descriptions for these continental sport contact 5 variants:

http://www.tyreleader.co.uk/car-tyres/continental/conti-sport-contact-5/

I can't really advise on what tyre pressure to use if you have highly varying loads, but I suppose the tyre pressure should be sufficient to cater for the heaviest load you will carry.

 

[ItalianTuneUp]

http://www.mbclub.co.uk/forums/members/mbenz1-albums-mercedes-pictures.html

Pictures. Will try to add some more if possible. Enjoy

Nice pics! I bet your dad is pleased with it. Did he get it for a good price?

 

[mbenz1]

Nice pics! I bet your dad is pleased with it. Did he get it for a good price?

Thanks. He really likes the car, especially the air suspension and the colour-combo with the wheels! Its a completely different experience from the W211 280 CDI he had. Much more refined, smooth, well-built etc... Can't wait for the run-flats to wear, so that they can be changed to non-RF tyres ... The vibration is the only thing that is stopping us from experiencing airmatic properly. Yes, the price was okay according to the other W221 320 CDI's on the market. It was a private seller, who is a doctor, really took care of the car and its got full MB service history with all documentation etc... We got a star-check done from local indy and thanfully it was clear . Atleast that's some re-assurance!

However, the car has a few slight problems such as the ambient lighting, which is bright at some parts but not at other parts and the previous owner fitted after-market LED number plate lights, which flicker when on... Might have to buy the OEM number plate lights from MB.... I have heard these after market LED lights can cause errors and flickering problems etc... The car is getting used to Shell V-Power diesel also...