faint knocking sound

[SDBxstr]

hey guys i could use a little help. i have a 01 986 ( love the car) there is a faint knocking coming from the upper roller , i had it diagnosed by ipd here in san diego we both heard it using a stethascope and pinpointed sound coming from upper roller. purchased new roller installed myself unfortunately knock is still there. any ideas your help would be appreciated
thanks mark

[yimmy149]

If you have a manual transmission, then you also a have a freewheel type alternator pulley. It will make some noise as the engine idle speed changes. Mine was making a lot of clicking, and made a screaming noise as it coasted after revving the engine. Replacing it solved the problem.

-james

[SDBxstr]

thanks for the reply, but the knocking sound was pinpointed with stethascope coming from upper drive belt roller . i replaced it but noise still there (only noticeable at idle) i have manual trans.

[ramo80]

Hey, did you figure out what was the cause of the knocking sound? I'm facing the same problem