W124 300D vacuum pump

[Gianni682]

I recently acquired a 1986 W124 300D, featuring a single previous owner and equipped with the OM 603.912 engine. The vacuum pump and timing chain should be inspected at 400,000 kilometres, notwithstanding its excellent performance. Regrettably, the owner did not maintain the service records, and considering the issues encountered with pump failures and dirt obstructing the timing chain, inspecting the pump is critical. Is there a suggested alternative to bulletproof materials? Has anyone installed an electric pump or alternator with a connected vacuum pump, similar to Japanese truck configurations? Could someone perhaps recommend a workshop handbook for this vehicle and engine? All online references are to American vehicles equipped with turbocharged engines. Thank you in advance.

[BENZE220AMG]

The Haynes manual, number 3253, unequivocally addresses that engine. I have utilised it for several years for my various petrol models, as evidenced by the photographs below, including the page indicating its applicability to your specific engine.

[BENZE220AMG]

[BENZE220AMG]

[DenishP4]

The handbook can be ordered online from the Haynes website; refer to the link below.

[DenishP4]

https://uk.haynes.com/products/mercedes-benz-124-series-petrol-diesel-1985-aug-1993-haynes-repair-manual

[Gianni682]

Thank you, DenishP4. I have not experienced much success with Haynes manuals, as they often lack sufficient detail on certain topics, but I will attempt to utilise them.

[migueldosantos77]

A friend installed a Honda Blackbird engine in a Smart Fortwo, and due to the Honda engine's insufficient vacuum for the brakes, he incorporated an electric vacuum pump from a Jaguar. That was effective, and while one might be inclined to believe that the smart can be quickly halted, it is not the case without a servo.

[Gianni682]

I will disassemble the pump this weekend to inspect it and the sprocket cam for signs of wear. A new Pierberg pump, following multiple model revisions, has ostensibly resolved the issues associated with earlier versions; yet, I remain apprehensive about the potential, albeit unlikely, risk of foreign objects entering the engine and interfering with the timing chain.

[DenishP4]

I acknowledge your issue; but, at present, that is the sole manual I am aware of that provides coverage.

By joining the 'official' club, the Mercedes-Benz Club, members gain access to the Mercedes-Benz Workshop Information System (WIS) and the Electronic Parts Catalogue (EPC), which are the same resources utilised by the dealer network. Mercedes-Benz permits this exclusively to one 'official' club in each country.