Over a year of hell.....

[DeanoPremo]

Desperate for some helpful input. My 2002 R230 (76k) has had a very loud tinny rattling/buzzing coming from what, (sounds like), underneath the front third of the vehicle, seemingly slightly more to passenger side. It rarely occurs on cold startup but once run to temp, is guaranteed to start whenever between 1800-2000 revs. Once warm, will also occur on startup.

New exhaust/cats, new accumulators, valve block, dampeners, engine mounts and literally months of down time have still not isolated the fault.

Only the pump has so far not been swapped out/refurbed.

Has anyone any experience or knowledge that could let me once again enjoy this great vehicle?

Bottle of premium tipple guaranteed reward for correct answer that nails this nightmare!!!

 

[Tim203]

Weird one, a friend has the same on an xc90. I couldn't find a heat shield loose, a rattle in the cat or DPF. Having said that I didn't check the rear silencer. Your problem sounds thermal related and points to exhaust. Sound is a funny thing, how's the rear silencer?

 

[Codger49]

My son's W208 had a noise as you describe and it turned out to be the exhaust's heat shield coming adrift from its fastenings.

 

[Auto-mobile]

Sl's are a money pit, did you do the gearbox mount?

 

[DeanoPremo]

Thanks guys, appreciate the suggestions!

The exhaust was renewed after the problem started and it obviously changed nothing but it does sound very much like the buzzy rattle a heat shield would cause. Maybe could have been missed?

The mechanic was convinced that the suspension system was the root cause but so far that has led nowhere.

Transmission mount is a new idea, seems unlikely but will investigate, thanks!

 

[Lyserman]

+1 on the exhaust shield.
They rot around the fastening and at first glance seem ok but do have the annoying habit of rattling.
Some 5mm stainless penny washers will sort it for not many pennies.

Hope it is something as simple as this.
Tapping the shield with a rubber mallet is a good way of testing them.

Tony

 

[flango]

I had this turned out they had used a cheap cat which was fine on start up but when up at temp rattled like a can of marbles due to the internals coming loose which is the opposite of what you would expect as things normally expand with heat.

Would def check heat shield and easy stuff first though

 

[grober]

Sounds as if it could be a hydraulic pump/controller has gone noisy. In your car this could be associated with the ABC [active body control] suspension or the SBC brakes. If the unit has gone noisy rather than faulty then it may not throw up any faults on Star. Best bet is go round the engine compartment+ under the wings with an engine stethescope when the sound is there- the engine will have to be running for this so be very careful not to get anything caught in the moving parts.

Mechanics Stethoscope Diagnostic Tool CAR VAN Engine Probing Sent 1st Class | eBay

 

[DeanoPremo]

Looks like the heat shield is worth checking again.... I saw the mechanic, (this car drove him to the brink of madness), banging away for ages on several occasions with the rubber mallet but it would be amazing if this was somehow missed and could be the cause....

He also spent many hours trying to isolate the noise via the stethoscope and every time we thought it was nailed and swapped out a component, nothing changed. The pump itself did not seem to be creating the noise but could only think if it was causing a fluctuation that resonated through the system, stopped short of refurbing and replacing as I quite frankly had run out of £££££.

So, so, fu##ing frustrating.

 

[DeanoPremo]

And yes, STAR was clear, everything seems to be working fine...

 

[DeanoPremo]

Been through the mill with this little beauty. Most of the usual early SL500 faults have happened on my watch. Front ball joints (refurbed front legs), water ingress into boot, (new seals fitted but still occurs every now and again), new engine mounts, central locking failures, stupid retaining clip in gear changer broke, etc, etc, etc.....