W210 320 CDi Engine Fault - Help Required (video inside)

[mwstewart]

All,
Hello, I have a 2000 W210 320 CDi that has covered 86k with full MBSH. The car has developed an engine fault and I'd like some opinions on the likely root cause.

- The problem occurred whilst driving flat out in 5th and the symptoms were a loss of power followed by a tapping sound, which remains.
- There is a knocking sound from one of the cylinders.
- I drove the car home following the issue and it doesn't appear to use any oil.
- The oil on the dipstick appears clean i.e. doesn't contain metallic particles or swarf.
- The water temperature has remained stable and the motor did not overheat at any time. It does not use any water and the oil is not contaminated.

If it were a petrol I'd say it had run lean and melted a piston, but I'm not sure if that scenario is applicable to Diesels? The amount of blow by makes me think the piston is damaged, a video is here:

Mercedes W210 E Class 320 CDi Engine Fault - YouTube

Does anyone concur with my diagnosis?

I'm a little disappointed I must admit as I really didn't expect this from such a large capacity and relatively under-tuned motor, but then I guess I took a risk by buying a W210.

 

[Tinkerer]

If it were a piston I would expect there to be more issues with oil, sounds more like a valve or tappet to me and, I am told, there are issues with 'vanes' breaking off in the inlet manifold that can give rise to these problems. If it has a full MBSH then they might be embarrassed enough to do it under warranty as it has only 89K on the clock. Good luck.

 

[mwstewart]

Thanks Tinkerer, I will get the manifold off and have a look.

 

[mwstewart]

All, For future reference. The W210 320 CDi era engine has a habit of bending the con rod on cyl 5 due to a fuelling issue; why its #5 on a common rail system I don't know - it may be down to the distribution design. The issue only occurs when driven hard and I can imagine most Mercedes owners don't drive their cars particularly hard hence it's not more common.

I had this confirmed by a Local MB Service Manager.