W163 ML270cdi exhaust smell when stationary

[8thumpers]

My w163 ml270cdi has developed a slight smell of exhaust fumes when stationary - say at traffic lights. If the recirculation button is on, or ventilation fan switched off, the smell fades away. Obviously it is sucking some dirty air in, but where does the ventilatoion system draw from? I cant find any evidence of noise from a leaking exhaust manifold.
It has had a new cylinder head fitted about 15000 miles ago - but the independent garage was a nightmare to deal with, so there is no way i'm taking it back! I assume something has worked loose??? any ideas greatfully investigated.

 

[delboy777]

Exhaust gaskets ie Manifold ones would be the first port of call then any joints in the exhaust system that are close to the engine bay. Carbon Monoxide is a killer so get it seen to sooner rather than later. Lift bonnet and with engine running have a listen and see if you hear any gaskets blowing past where the Manifold is bolted to the cylinder head, you will hear a clicking type noise when the throttle is pressed down a little as the back pressure increases.

 

[kebo57]

Exhaust gaskets ie Manifold

I heard that the Manifold to Engine gaskets are not fitted at the factory so you might not have one but you can get them from MB & fit them

You might have problems with shearing the studs off when you remove the old nut from the studs that hold the manifold to the cylinder head
I just repaired three stud on a ML 270, you might want to go with the torque setting when re tightening them as I sheared one off my self when refitting the manifold with a gasket
there are ways to remove nuts with out much difficulty

Kevin

 

[rpe2]

My w163 ml270cdi has developed a slight smell of exhaust fumes when stationary - say at traffic lights. If the recirculation button is on, or ventilation fan switched off, the smell fades away. Obviously it is sucking some dirty air in, but where does the ventilatoion system draw from? I cant find any evidence of noise from a leaking exhaust manifold.
It has had a new cylinder head fitted about 15000 miles ago - but the independent garage was a nightmare to deal with, so there is no way i'm taking it back! I assume something has worked loose??? any ideas greatfully investigated.

I would guess that you have a leaking injector. Take the plastic cover off the top of the engine, if an injector is leaking, there will be a golden/ black goo surrounding it.

 

[Xtractorfan]

Yea I would go for the blowpast on the injector,, once you have the cover off allow the engine to tickover and run your hand along the top of the injectors and you should feel the blowpast on the offending article..

 

[Duncan.ml]

Hi, I had exactly the same problem on my 2000 ML 270 cdi and it turned out to be a leaking injector. Cost about £70 to get it fixed.

 

[JEZ.S320L]

Agreed - leaking injector seal/s. I had EXACTLY the same problem with mine.

 

[pault8084]

Hi, I had exactly the same problem on my 2000 ML 270 cdi and it turned out to be a leaking injector. Cost about £70 to get it fixed.

Well worth 70 quid to be fixed properly.Normally need injector seats cutting as i found out at my expense.Tool's about £200 so if you can borrow one or find a proper repairer as a new washer and bolt rarely works(if this is the proplem)

 

[8thumpers]

Cheers guys - I had the injectors replaced and a re-con head fitted too 15k miles ago. I know the head inside out now and have looked at the injectors - all okay. They did smell before being changed but that was more of a diesel oil smell than fumes as now. Its my guess that the manifold is leaking somewhere. Anyone know where the inlet for the ventilation system is?