Thread: Smoke on idle/start - 300 Tdi fuel pump drift

Smoke on start up is normal for a 300 Tdi
Smoke at idle is not normal

if its smoking on idle only when its cold the rings are shot and its loosing compression while cold. A cold/hot compression check and leak down check will quickly identify this for you.

Hi Dave, no difference hot or cold. No indications of blow-by. Smoke is diesel only. Can dig out my gauge and do a compression test on the weekend but don't think that is it.

that'll be belt stretch, pump slip (worn) or injector dribble.

it might also be worth checking the valve adjustment.

Belt is new. Pump is not (apart from seals). Injectors are suspect.
Valve clearances were done 10,000 kms ago when the head gasket was changed (by me) and smoke was the same before and after this.
Can pump slip/wear be reasonably corrected for by smoke screw adjustment?

Injector dribble is the most likely culprit.

Edit: kms are 310,000. Head gasket, big ends, timing belt, fuel pump head seal etc (and lots more not relevant to this discussion) done between 290,000 km and 310,000 km by me. Apart from the fuel pump head seal, everything was maintenance only and looked perfect. Injector spray pattern looked good.

Originally Posted by damienb

Belt is new. Pump is not (apart from seals). Injectors are suspect.
Valve clearances were done 10,000 kms ago when the head gasket was changed (by me) and smoke was the same before and after this.
Can pump slip/wear be reasonably corrected for by smoke screw adjustment?

Injector dribble is the most likely culprit.

Edit: kms are 310,000. Head gasket, big ends, timing belt, fuel pump head seal etc (and lots more not relevant to this discussion) done between 290,000 km and 310,000 km by me. Apart from the fuel pump head seal, everything was maintenance only and looked perfect. Injector spray pattern looked good.

Check your Crankcase ventilation system, clean little cyclone attatched to rocker cover, while idling undo oil fill cap and leave sitting in it's hole and see if the blowby bobbles it around or blows it clean off, good luck, Regards frank.

I've got a provent oil separator on it, but it's not compression problems. Winding the idle (smoke) torx screw out a full turn (from factory) has eliminated smoke on idle and dramatically reduced smoke on start so I suspect pump or injector. I would have thought though pump lobe wear would result in less fuel, not more. Takeoff and driveability have not changed.

Originally Posted by damienb

I've got a hiclone on it,

Remove! It's just an intake restrictor creating lower air flow. There's a turbo downstream that creates 5.5 million% more turbulence than your twisted bits-of-tin thing.