Greetings from Finland!
Tried to locate the MAF sensor (for cleaning it up) from my dad´s -96 312d, but not sure for the right sensor. It seems that the intake line in 312d goes like this:
1. filter-box
2. tube to turbo
3. turbo
4. tube to intercooler
5. intercooler
6. tube to intake manifold
7. manifold
I quess the MAF sensor is located in tube number 7., i.e. tube from the intercooler to the manifold. I found a picture of the similar engine bay from the site:
MERCEDES SPRINTER 2,9TDI 312D ANGLIK WLKP (336152011) - Aukcje internetowe Allegro (picture I ment is "10qo7.jpg"). Tube number 7. is the "S" curved tube going from the front and round the engine: there can be seen two sensors, one with rectangle shaped box attached and "round shaped" sensor housed under the first one. Which one is the MAF sensor? And what might the other one be, MAP sensor or intake air temperature sensor or so?
About the MAF sensor: what kind of sensor is used in 312d (OM60298 type engine, probably, 2,9litre that is), I quess there was at least two options, hot film or hot wire type of sensors in the market at late -90´s? I have only cleaned hot wire type sensors since driving a Ford (I know, don´t start it with me

) Is there any differences about cleaning the sensors due to the two different functional types? I have cleaned the hot wire type sensors simply with proper solvent, CRC air sensor clean spray or similar prods.