checking cranking speed/rpm on a diesel

Post by **uglyboatman** » 26 Jan 2006, 08:56

Hi is it possible to check the cranking speed of a starter using a normal autotester/voltmeter- if so - how do you connect it up ?, mine have a rpm/tach setting on it but i get the feeling its not possible on a diesel ? Just trying to check if my starter is up to scratch.

Cheers

Post by **Mocki** » 26 Jan 2006, 09:01

not sure if it will work, but you need to connect to the "w" connection on the alternator to get a rev counter out put.

Post by **Ade** » 26 Jan 2006, 10:57

multimeter rev counters use the spark signal so wont work on a diesel, an optical rev counter is probably the easiest way to measure cranking speed
or a diesel rev counter that takes its input from the injectors

The alternator signal (from the w terminal) is not linear so unreliable at low revs

Post by **uglyboatman** » 26 Jan 2006, 13:24

cheers,

the article i was reading said to check for a cranking speed of 150rpm, and had some kind of special vw tool i think that was a TDC sensor i think- which i guess is like the optical rev counter mentioned.

I guess 150rpm will be way to low to check on the alternator then ?

Cheers for the replys