W140 - What pressure? Vacuum Line Test for Soft Close, Central Locking etc

[yojay]

Mods - unsure what section to post this under?

Hi folks,

My vacuum pump located under the rear seat bench for soft close, central locking etc, has given up on my 1997 S420. I believe this is due to the motor burning out from running for long periods of time, trying to draw vacuum with leaks present.

I have bought a new vacuum pump suitable for my vehicle but would like to test each line and fix any leaks before installing the new pump.

To test for vacuum pressure and leaks I have bought a kit from good ol' eBay as pictured. :wink

My question is, does anyone know what pressure (using the units on the display gauge) the lines should be able to hold and for how long roughly?

Any advice on testing or replacing leaking items from anyone who has done this job before would be much appreciated! :thumbsup:

TIA

Vacuum Tester 1 by yojayLDN, on Flickr

Vacuum Tester 2 by yojayLDN, on Flickr

 

[grober]

mbar to mmHg Converter, Chart -- EndMemo
Gives a conversion factor of of 1mbar=0.750062mmHg [ millimeters of mercury] the units the vacuum gauge is measured in.
Commonly quoted figures for pump limits around that time w124/w126 are 650mbar which equates to 487mmHg. On that basis I owuld aim for a test vacuum of 490-500mmHg??
these may be of interest - remember that on the W140 the pump can function in two ways to provide pressure or vacuum. To test empirically you could just hitch up your pressure gauge to the pump and see what vacuum it draws before testing any lines?
K6JRF Auto Page
and

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