Your description of the problem could use some more details. Actually, "tensioner bouncing alternator", if read as [subject, verb, object] doesn't mean much to me. However, you might get the help that you want by pretending that your car is a TDI and asking around at tdiclub.com. That is probably the most knowledgeable, mature, helpful forum for VWs around. Just don't forget to search the forum first. Like anybody, they get tired of answering questions that have already been dealt with and can be quite stern about it.
most likely the alternator is bad.
front side of engine near the alternator
Begin by loosen the tensioner bolt. Slide the alternator to the left and remove the belt. Remove the wiring harness from the back of the alternator. Remove the alternator retaining bolts.
No
The 2003 Volkswagen Jetta has 8 valves.
The 2010 Volkswagen Jetta has 20 valves.
The 2002 Volkswagen Jetta has 8 valves.
The 2011 Volkswagen Jetta has 8 valves.
The 2014 Volkswagen Jetta has an inline 4 engine.
The 2004 Volkswagen Jetta is a gas-powered vehicle.
The 2007 Volkswagen Jetta has an inline 5 engine.
The 2008 Volkswagen Jetta has a 5-speed manual.