lionelhutz

That is the adjuster and that arm does rotate inside that round body attached to the engine.

Does it wiggle front to back or inline with the belt?

If it is front to back then for sure replace it because it should not have front to back movement.

If it is inline with the belt then it might be normal movement. That could just indicate a slight engine rpm variation (misfire?) which is causing the belt to continually pull it a little looser and tighter. It could also be another pulley or the water pump or the alternator causing the movement.

If you hear no funny noises from the belt drive and it looks smooth besides that movement then it likely isn't that big a deal and not likely you'd have a failure any time soon. But, if you really don't know, it might be a good idea to have your mechanic give it a look.

Ed Ramberger

The HB looks like it has a little wobble - but it's kind of hard to tell. Some will say there can be zero wobble and some will say there can be some. After all the years of working under the hood, I have seen so many of these with a tiny amount of runout that were nothing to worry about. They are constructed with an elastomer ring between a mounting hub and an outer ring/pulley that the belt runs on - and over time the rubber can degrade and the rings can walk apart.

If you are concerned that the HB outer pulley may be separating from the inner hub or may be moving, take a white or yellow paint pen and on the face of the pulley as if looking at the front of the engine - make two or three paint marks that go across the face (metal hub - rubber center - metal outer) You can then monitor and see if the marks on the outer ring and inner hub begin to walk apart.


I make 3 marks so wherever the engine stops, I can typically easily see at least one of them while under the hood.

I just did a generic web grab and threw a few lines on so you know what I mean.