Squealing and revs on T4 1.9TD

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Fri 23 Dec 2005 13:07
Squealing and revs on T4 1.9TD - SlowThing
Hoping someone can help with this one. My T4 (1.9TD) has started to squeal for a few seconds when I start the engine (sounds like a slipping belt). Yesterday when I left work I noticed that while it was doing this, the rev counter needle was only showing about 300 revs, although the engine is reving normally. As soon as the squealing stopped the revs rose to the normal 850 or so at idle.

Does the tacho get its signal for engine speed from the alternator? If so would this would explain the low reading if the belt was slipping a bit when cold - causing the squealing. I thought the belt was tensioned by a spring loaded roller - so how can it slip? Could the squealing be the alternator bearings starting to die? As the squaling starts to lessen the rev counter needle flickers a bit, and when the noise stops altogether the needle then rises to its normal posistion.

The battery light didn't come on but maybe it had enough 'oomph' to prevent this.
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Fri 23 Dec 2005 13:28
Squealing and revs on T4 1.9TD - Altea Ego
"Does the tacho get its signal for engine speed from the alternator?"

Being a diesel, yes it does.

If so would this would explain the low reading if the belt was slipping a bit when cold - causing the squealing.

Yes it does. The squeeling and tacho indicates your belt is slipping.





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TourVanMan TM < Ex RF >
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Sat 24 Dec 2005 11:02
Squealing and revs on T4 1.9TD - Cyd
The squeeling is telling you that your alternator belt is slipping. It does this at start up when the underbonnet is cold and there is slight damp on the belt. The belt is also under heavy load at this point because the glow plugs are still on and the battery wants its start charge back - which it probably isn't getting if the belt is slipping. The belt is likely to be badly worn, possibly to the point where the tensioner can no longer keep it in proper tension. Have the belt changed forthwith and have the tensioner and alternator checked at the same time. Make sure the pulleys are cleaned before putting the new belt on.
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Sat 24 Dec 2005 13:02
Squealing and revs on T4 1.9TD - Screwloose
Slow Thing

Depending on the year, your alternator may be fitted with an over-run clutch built into the belt pulley.

These have been known to give problems - particularly squealing - at start-up.
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