Hi all diesel aficionados

I'm a proud owner of a '92 300D 2.5T (W124) since last march. The car is approaching 180 000 miles and, although it has needed some efforts to heal what appears to be a recent lack of maintenance, it is in a very good overall shape.

I'm thinking about an injectors replacement job. I don't have any previous records for the car so I don't know if injectors were already replaced at some point. The previous owner was a long time diesel owner and when I bought the car, he told me that injectors would need some work though it was not immediately apparent to me.

But since I'm now more familiar with the car, I think that may be a needed job. First of all the glow plugs look to be Alright : the car always starts easily with minimum glow time with temperatures near freezing. It starts on all 5 cylinders and it is relatively quiet for the first 30 to 60 seconds. Then it gets noisier, misfires and emits white smoke until it gets warm (maybe 3 to 5 minutes when the temp is around 40 F). The misfire is more apparent when the engine is under part load at around 2000 rpm.

At first I was thinking about some kind of engine electronic management problem, but that system only works on egr and intake pressure, which neither seems to operate when the engine is cold.

An another clue that I believe points to faulty injectors is a very noticeable puff of black smoke when the engine is restarted after a few minutes stop (leaking injectors ?).

When the engine is warm, there is no apparent misfires, but the 5 cylinders rhythmic could fouls me. The IP timing looks to be good as there is no smoke driving in town or on highways. The average fuel consumption is around 28 miles per Imperial gallon, which I guess is about 23 mi / US gal. (50-50 town-highway). Highway only is around 28 mi / US gal. Those figures could be on the low side (wrong spray pattern ?).

Could some specialists confirm the diagnosis ?

__________________
DR
1992 300D 2.5T 351 000 km