(Resolved in post #9)

Anyone out there have this same issue? When the car idles below 1300RPM the alt/serpentine auto tensioner makes a loud knocking sound when the car idles/cams lope. I put a different one on the car and it made the same noise. Car has GSC S3's.

I'm thinking there's no way around the issue without increasing the idle unless someone made their own manual tensioner for the belt.

 

no issues over here, mine idles at 1100-1200 and ive never heard anything out of the ordinary.. im running buschurs BF272's

 

No issue here I have fp5r cams and like 1100 rpm idle cams lope hard

 

Are you 100% sure that it is the tensioner? I don't mean to bring up any panic, but is it possible that you have rod knock? The only reason why you would even hear the tensioner is if it was set much to loose.

-pal215

 

It is not rod knock, it is definitely the tensioner. It made the same noise on two different motors; my old stock one which was perfect when torn apart and my new built one.

Two local Evo guys have had the same issue. I put my head right next to it and its blatantly obvious its the tensioner as it makes the noise when the tensioner physically moves back and forth against the belt when the cams lope. I think maybe both tensioners I tried on my car were not in good shape and just worn out. Maybe I will try a new one.

 

The only reason why you would even hear the tensioner is if it was set much to loose.

 

^ You can't adjust the tensioner. It's spring loaded. I would try a new tensioner. I have gsc s3's and at 1100 idle no issues or sounds that u speak of.

 

gsc S3's and not issues at all here.

How is your belt conditions? on really old ones we have seen this tensioner clunk issue, check it out

 

Thank you for mentioning the belt. It lead to a resolution..

I thought about it and remember I run a Gates K060578 which is 58 3/8 long for deleted A/C. When you release the tensioner to press on the belt, it turns a good amount to add tension to the belt.. a lot more then my stock daily driver Evo tensioner does. I went and got the K060569 which is 57 1/2 long which fixed how far the tensioner has to reach for the belt and took care of the knocking noise

So in the end.. if you're deleting your A/C, run the 57.5" long belt. I hear the 57 is a bit too tight.

Scott

 

Good advice Scott! Indeed the K060569 is the correct belt to get.

 

They sell a 57-1/2 at NAPA, which is a Gates.