Timing belt whine and hum...

77SudTi · #1 (**permalink**) 10-05-2007, 06:46 AM

Does everyone get this on their 8V engines? I recently checked my timing belts and they seemed a little loose (worn themselves in since the rebuild) so I thought I would tension them up a bit. I tensioned them up to what the manual recommends and they made a heck of a racket, especially at about 1000rpm and a whine was detectable at speed once warm, which sounded cool

but probably wasnt helping my belts (engine expanded = tightened belts = whine) so I loosened them off slightly and the noise has almost gone, still a slight hum at ~1000rpm. I figured if I loosen them off a little to what the manual says, as the engine gets hot (and expands) an acceptable tension should be reached.
Opinions, comments...

sprint#37 · #2 (**permalink**) 10-05-2007, 07:27 AM

Did you check the bearings of your tensioners..?

enri · #3 (**permalink**) 10-05-2007, 03:32 PM

i found you have to grease the back of the tensioner pulley bracket so when you release the nut the spring flicks it against the belt. otherwise the friction works against the spring and you have to keep guessing how much to load it up.

77SudTi · #4 (**permalink**) 10-05-2007, 05:41 PM

Tensioners were re-newed when I did the rebuild, and the grease behind the tensioner sounds like a good idea, but I still find the springs aren't quite enough, and need a tiny bit extra just as they are tightened.
I've known all 8V boxers to make some sort of a hum, probably just a natural resonance from the belt at certain revs