What might cause of smoke of w124 230E?

Answer 1

The W124 230e motor is a fuel injected 4 cylinder petrol motor incorporating Mercedes reliable CIS injection. Having owned many cars with this engine they are almost indestructable with normal use.
Whilst all Mercedes engines of this time do use oil between service, it is fair to say that the smoking of the engine accompanied with oil consumption of greater than that recommended points to something wrong. Yes, they do wear out, but some times the signs mask the cause.

Firstly the colour of the smoke offers the first hint to the problem.

Black smoke, rough running, soot on the tail pipe may well be a fuel problem.(too much being burnt in the cylinder during normal running)
Grey smoke is usually oil being burnt in the the cylinder.

Lets start with the fuel issues. This can be caused by many problems:

Leaky fuel injectors, leaky cold start injector, faulty fuel regulator, faulty fuel distributor or any combination or interconnection of the above.


The grey smoke could be the oil seals on the piston being severely worn or broken and sucking oil up from the sump into the combustion chamber. Most commonly it is wear in the head that causes smoking, usually just on start up then clearing shortly after this is particulary noticeable if the car was parked and due to the warmth of the oil running in the valve gallery.
Mercedes heads usually need attention below 200,000 km due to the wear in the valve guides and the perishing of the valve guide seals under the cam shaft. Bear in mind many cars need new engines at this stage.

Cars that have been overheated or run low on oil can suffer irreversible damage.

Always check all rubber tubes and breathers for cracks and the tubes between the rocker (cam) cover and the air cleaner for moisture and other grundge build up as when blocked they can cause pressure to build in the engine, sometimes causing oil to go where its not wanted.

Always try and localize what each cylinder is getting.
Removal of the plugs for inspection is the first step. Refer to colour guides for diagnoses.
A compression test for each cylinder is useful in some cases but not all.
The combination of the two above usually reveals a lot.

eg all cylinders plugs except one is clean and other is sooty, with a corresponding low compression on that cylinder, points to rings perhaps.

It is normal for the outside cylinders to show wear signs earlier than the inner ones eg 1 and 4 .

Good Luck


Good luck