What could it be?

[balleballe]

I have had my w212 e350 for around 2.5 years now. In the past 2/3 months I have noted the following:

Horrible smell when engine first started with excessive whitish smoke. It's a toxic type of smell, not sure if that would be diesel or oil? The smell subsides a fair amount after a decent drive but is still there if the car is in idle and I walk around it.

Rough idle when the engine is cold. Occasionally feeling a 'judder' which shakes the entire car

Slight reduction on fuel economy. My driving habits and my route to work have not changed but compared last winter my MPG is around 10% lower

No engine lights and I always keep on top of general maintenance with genuine merc parts and oil.

I can't see any apparent leaking around the injectors, nor any obvious coolant leak. Car does not seem to be consuming any oil, and no stains on my drive overnight.

I'm going to take it to my local mechanic when I have time but wondering what it could possibly be? He's a general mechanic so it would help if I could point him in the right direction

Also, I've had to top up my coolant twice in the last 6 months which I don't think is normal, no apparent leaks

Car is on 145k if it helps. Any help would be appreciated

 

[ALFAitalia]

Sound like a leaky head gasket letting coolant into the combustion chambers. Any fault codes?

 

[Trickythemerc]

How much coolant do you have to add to bring the level back up ? As Alpha says head gasket leaking coolant would explain the white stuff coming from the exhaust and possibly the rough running from cold.

 

[Tonygw]

Needs to be hooked up to a STAR diagnostics, but to me sounds like an injector fault. STAR can read live data including injector data. This will show up anything incorrect.

Needs to go to a specialist with Mercedes STAR software for the best, quickest resolution.

 

[toteimerced]

I’d be checking for intake and boost leaks, the orange intake seal and the green crossover pipe seal, maybe a smoke test will be wise.

 

[balleballe]

Awesome, thanks guys.

Coolant top up has been around 250ml. I thought coolant was supposed to smell sweet? This smell is rather rancid

 

[W1ghty]

Awesome, thanks guys.

Coolant top up has been around 250ml. I thought coolant was supposed to smell sweet? This smell is rather rancid

Leak on the windscreen washer reservoir which has gone mouldy ?