knocking noise

[VBCAVMAN]

Have 95 Lesabre with a knockin noise on the right side. Thought it was ps pump and changed it but still have noise. Is it possible that the belt tensioner
is knocking. When I rev it up past 1500 rpm the knocking stops. Let off and it starts back up. Really loud when ac is on. Also the notch on the side of the tensioner is not seated all the way to the lowest position when car is shut off. Help.

[HotZ28]

Have you checked the outer ring on the harmonic balancer?

[VBCAVMAN]

I dont see any indication of a problem with the balancer. The little arrow mark on the tensioner is about a half inch from the base of the tensioner. I can actually see where it says lift on the tensioner.

[HotZ28]

When you observe the tensioner with the engine running, is it jumping up and down, or does it appear to be steady? Did you put your hands on the outer ring of the balancer & try to rotate it back & forth? (Of course, with the engine off)

[Blue Bowtie]

If you remove the accessory belt and run the engine, does the knocking persist?

[VBCAVMAN]

Did not try to rotate outer ring on balancer. However the tensioner does jump
up and down when engine is idling. What do you think?

[VBCAVMAN]

Whe belt is removed there is no knocking noise.

[Blue Bowtie]

That narrows it considerably.

[spinne1]

Originally Posted by VBCAVMAN

Have 95 Lesabre with a knockin noise on the right side. Thought it was ps pump and changed it but still have noise. Is it possible that the belt tensioner
is knocking. When I rev it up past 1500 rpm the knocking stops. Let off and it starts back up. Really loud when ac is on. Also the notch on the side of the tensioner is not seated all the way to the lowest position when car is shut off. Help.

Yes, mine knocked after I reinstalled it after an engine rebuild. I cleaned it and I think I cleaned it too good and got some of the grease out. Oops. Anyhow, you should be able to tell if it was knocking because it would physically move as it was knocking and you could look at it and see it move.

EDIT: just read that yours is jumping--therefore I think you have found your culprit. Your tensioner is likely dried out of grease and therefore is "catching" and not spinning smooth. You can either remove yours and attempt to grease it up good (don't know how easy it would be) or get a new one or one from a junk yard.END OF EDIT

As for other potential causes, does it happen with the ac compressor engaged? disengaged? both? Does your harmonic balancer look smooth when it turns? Can you feel your crank sensor (when the car is not running) and see if it is affected/damaged by the tines of the harmonic balancer? Can you watch the harmonic balancer turn under the car while running (use jack stands and a good flashlight)?

To further help, get a length (2-3 feet) of thick vacuum/fuel tubing or just garden hose and use it as a stethoscope to hold it to various parts of your car to listen for the sound to see if you can pinpoint it. Hold the other end to your ear (obviously.) Try listening to the alternator, the ac compressor (but not the moving parts!), the power steering pump (not likely it but you know), and various other engine places until you narrow the search.