Ok I'm stumped and annoyed.

I've replaced the belt with a brand new belt, I've tightened it to reccomended tension. But the other day I stalled it and they were screaming. Like loud. I tightened it more and it stopped but they are slowly getting louder again.


Only thing i can think of is the tensioner is failing or walking out.

Is this a known issue with Z's? Or is something else common for this to happen with these cars?

 

This isn't a known issue with the VQ. How did you measure the required tension and what brand of belts did you use?

 

Brand I'm not sure I gatta look at the packaging when I get home.

But I used the thumb truck, the twist trick and measured the longest section with a micrometer and a ruler of 3-4 mm of deflection.

 

You may have a tensioner that's defective. I believe the FSM calls for 4-5 mm of deflection by simply pushing (lightly) on the long section of belt.

 

That's what I'm thinking because when I retighten it it stops. But seems to work back into squealing. As if it's getting loose again.

 

My Z is an HR so I have the serp belt, but ny old BMW 635 uses 3 regular V-belts. First time I changed them I bought the cheap (likely Asian-made) belts for ~$7 each from Advance. Within a few hundred miles they had stretched and got noisy, and I was unable to keep them tight. Trashed them and went to NAPA, bought their Premium (US-made by Gates) belts for ~$20 each, and had no issues. They also don't need to be run nearly as tight, which will save all the bearings in the accessories.

 

Gates ftw!