Author Topic: Source of Tachometer Problems? (Read 2386 times)

ibmserf · « **on:** March 02, 2007, 09:21:42 am »

Having trouble with my tach for the first 30 secs after I get 'er going. 97 1.9L TD. I suspect it is due to problems I have been having with my accessory belt- as soon as the tach kicks in again, I'm hearing a bit of a squeeling from the area where the belt is located. I guess the question I need to ask is, does the tach run off the accessory belt drive? I suspect that the belt is slipping for the first 30 seconds, then somehow starts pulling again.

Any ideas, please let me know.

Vincent Waldon · « **Reply #1 on:** March 02, 2007, 09:39:12 am »

The tach runs from a signal generated from the altenator... so what you're probably hearing is your altenator kicking in and the sudden load making the belt slip.

On mine (a much earlier version) the red altenator light stays on and the tach is goofy until I give it that first rev over 2500 after starting up.. the light goes out, the tach becomes normal, and if the belt is loose it then starts to protest by squeeling.

jtanguay · « **Reply #2 on:** March 02, 2007, 10:10:27 am »

mine is doing the same thing... whenever theres a huge load the belt just slips... i'm probably going to get a new alternator pulley and also tighten up the belt a little bit more.

ibmserf · « **Reply #3 on:** March 05, 2007, 10:45:53 am »

I think I'm going to go with the one-way clutched alternator pulley...Can anyone confirm the part # I found on another post? I have a '97 1.9L TD...Part number I found is: 028 903 119AA- I think this is used on TDIs and will fix most of the vibration...

Mark(The Miser)UK · « **Reply #4 on:** March 05, 2007, 11:40:31 am »

Vincent is on the nail...
Your belt may be a little loose. But you can tighten up the belt until the cows come home; tach will not fire up until certain revs have been reachedand the alt begins charging. whether its 2500 for all, or varies downwards for individual alts. it'll hold true . Tach gets power from 'w' terminal on a diesel alt. some diesel alts and all gasser ones do not have this terminal. Possibly makeable though :wink: