82PS DI engine no longer starts

The engine now has just 100,000km down. Although the glow plugs were changed at 80,000 the last time and also regularly the diesel filter was renewed – the engine does not start any more. My FOH has connected its clever device could not find a Felhler message. He said with diesel engines a injection pump error would not be indicated. After 3-hour troubleshooting the master – the injection pump must be replaced against a NEW -. Costs for this with E 2.350,- Euro – if nothing else is added. If someone knows – it can also be something else – or is it really the pump and this really is TEUER. The FOH could not even tell me if it is a Bosch pump or another. One could not check this also – only change against a NEW – the ALTE – should be disposed of but the first has to be removed so that a NEW one can be ordered there are about 10 different pumps the Can someone help me or give me a tip. Thank you very much in advance.