Vibration - 1.9L TDI AFN Serpentine Belt Tensioner

[Achilles3588]

91 Doka with recent 1.9L AFN TDI engine swap.

Installed a 90A 'remanufactured' Bosch alternator with a new clutched pulley and using a serp belt configuration during the engine swap. Purchased the alternator unit from an eBay supplier.

The bearing(s) on the reman'd alternator failed after less than 2K miles. I suspect but can't prove the replacement alternator was not a quality product; so rather than make a warranty claim (and take the risk of a low quality replacement) a replacement was sourced from what is IMHO a known quality supplier (AutohausAZ). Reused the original clutched alt pulley upon alt installation.

I was concerned about tension on the belt and on the alt pulley. It seemed to take excessive force to relieve the tension on the belt at the tensioner when removing and replacing the belt, and of course, the original alt bearings had failed. On the recommendation of an experienced mechanic a slightly larger quality serp belt was sourced and installed in an attempt to address this.

Installed the larger belt with no trouble however upon restarting the engine a slight vibration was noticed in the belt tensioner which was not noticed previously.

Is this normal or is it perhaps signs of another problem? There is no noise associated with the vibration (as there was when the alternator bearings began to fail). Might the clutched pulley have been damaged at the time the alternator failed? Have not taken the rig out on the road and up to full running RPMs until I have some idea if this is indeed a problem.

Thanks much for any advice.
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Larry V.~
'91 Syncro Doka 1.9L TDI 'AFN'

[vanis13]

Suggestion - put your engine type in your topic title. May catch the eye of those with that engine swap/experience to open up topic and will be easier to find in future searches plus it will make it clear to those w.o experience w.Your engine to open topic or not.
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83.5 Westy with Subaru 2.5, 4 spd manual, center seat, COLD A/C on 134a!, Winter camp heated with an Espar B4 gasoline furnace

www.SuperVanagon.com - some stuff I make

[?Waldo?]

Can you post a video?

Does the clutched pulley still rotate one direction when the center of the alt is stopped? Sick a screwdriver carefully into the armature to stop it from rotating and try rotating the pulley each direction. It should slip one direction but should not slip the other direction. If it doesn't slip either direction it has failed. If it slips both directions it has failed.

[Achilles3588]