Diesel Smoke

[bigharj]

My E300TD (1998) is giving me cause for concern, it's chucking up smoke in 2 ways.

1) When starting up from cold, it gives out lots of blue/white smoke and the engine makes a horrible clanging sound. But about 2 mins later the smoke disappears and the engine ticks over nicely. The glow plug light remians on for about 5 mins EVERYTIME I start the engine.

2) When I kick down from slow speeds I leave a large plume of black smoke, I know some diesel engines do this as a matter of course but I would have thought a Merc engine would be more refined any ideas ?

Any assistance very much appreciated.

Harj Bains
[email protected]

 

[Brian WH]

My E300TD (1998) is giving me cause for concern, it's chucking up smoke in 2 ways.

1) When starting up from cold, it gives out lots of blue/white smoke and the engine makes a horrible clanging sound. But about 2 mins later the smoke disappears and the engine ticks over nicely. The glow plug light remians on for about 5 mins EVERYTIME I start the engine.

2) When I kick down from slow speeds I leave a large plume of black smoke, I know some diesel engines do this as a matter of course but I would have thought a Merc engine would be more refined any ideas ?

Any assistance very much appreciated.

Harj Bains
[email protected]

When was it last serviced mate.

 

[Tigger]

1) When starting up from cold, it gives out lots of blue/white smoke and the engine makes a horrible clanging sound. But about 2 mins later the smoke disappears and the engine ticks over nicely. The glow plug light remians on for about 5 mins EVERYTIME I start the engine.

This usually means that one or more of your glowplugs need replacing. They are not pre-heating the cylinders from cold properly which means that the engine is struggling to ignite until it eventually warms up.

2) When I kick down from slow speeds I leave a large plume of black smoke, I know some diesel engines do this as a matter of course but I would have thought a Merc engine would be more refined any ideas ?

A small amount of smoke is normal but if you are getting a huge plume then check your air filter as any restriction in airflow will result create excessive smoke.

 

[jimmy]

The smoke at cold start and glow plug light staying on means you have at least one glow plug faulty. The clanging should not last two minutes, 20-30 seconds maybe.

The smoke at kickdown is partly caused by low turbo speed, when you boot it, the ECU squirts in more fuel but the turbo is not blowing in enough air so the engine is overfuelling until the turbo gets upto speed (not quite that simple as the engine has sensors to compensate for this).

Also the engine has an EGR valve, Exhaust Gas Recirculation, this recirculates some exhaust gases to re-burn them to lower certain gas levels (Dieselman will/can explain in more detail), I blocked mine off to prevent it working and the puffs of black smoke have nearly completely gone.

Worth doing some basic checks, is the air filter clean? Try using a dose of diesel injector cleaner, but definetly get your glow plugs checked, the fault light should reset after one or two starts.

 

[Dieselman]

The smoke at cold start and glow plug light staying on means you have at least one glow plug faulty. The clanging should not last two minutes, 20-30 seconds maybe.

The smoke at kickdown is partly caused by low turbo speed, when you boot it, the ECU squirts in more fuel but the turbo is not blowing in enough air so the engine is overfuelling until the turbo gets upto speed (not quite that simple as the engine has sensors to compensate for this).

Also the engine has an EGR valve, Exhaust Gas Recirculation, this recirculates some exhaust gases to re-burn them to lower certain gas levels (Dieselman will/can explain in more detail), I blocked mine off to prevent it working and the puffs of black smoke have nearly completely gone.

QUOTE]


From now on I will teach no more as the student is now well learned! All sounds pretty accurate to me.

 

[pepper&boulou]

I have noticed on my 300D that the glowlight is not comming on at all on first startup but works ok the rest of the time. your thoughts please.

 

[Dieselman]

I have noticed on my 300D that the glowlight is not comming on at all on first startup but works ok the rest of the time. your thoughts please.

Assuming the glowplugs are getting power then it must be the pre-glow relay. This brings on the dash light, the actual glow plug relay is a bit more juicy and stays energised after the engine has started.