Boeing 717

Ever since I've owned this car I have had EXCESSIVE belt whine. To the point where all you can hear is belt over the engine and exhaust. It literally sounds like I'm driving a sewing machine. And I friggin can't stand it.
So I bought a mechanics stethoscope and nailed it down to the belt roller just above the bottom balance shaft.
I removed the roller and the belt noise COMPLETELY disappeared! So now I have to find a position of the roller that massively reduces the amount of noise because the factory setting does not allow it. So I moved the roller up to the point where it was touching the top span of the belt and actually deflecting the belt a millimeter or so, a very small amount. That reduced it probably 80 percent.
So I took the car around the neighborhood and suddenly at 3000 rpms I would get a large vibration and ratcheting sound. Climbed under car this morning and took it all apart AGAIN and sure enough the lower balance shaft had rotated almost 180 degrees out of position.
I'm wondering if the balance shaft rotated while I had the roller off OR while it was in its new position, apparently it's pretty important that it's in a position to keep the belt in place. Do you guys have any experience with this? I'm thinking I have to find a position that is .5 mm above the bottom balance shaft and still touches the top part of the belt to reduce noise.
I have the belt tension correct according to the Arnworx tool which is .06-.14.

Any advice would be greatly appreciated.

thomasmryan

I would tighten the balance belt just a little more and set the idler again.

it looks like you have the quieter style belt teeth but you might inspect the balance cogs for wear. they do wear on the pull side of the tooth grove.

Boeing 717

Thanks Thomas.
All the cogs and rollers are less than 2000 miles old they are in good shape.
I found a spot that allowed me to touch the top part of the belt but I had to go 1 mm over the bottom balance shaft instead of .5
There was no position that I could find that would allow .5mm and touch the top of the belt and I tried numerous configurations.
I think this will work well. And like you said I went just a little tighter on the belt.

spanky

across the family range of models( 944,951,968, that I have owns and worked on, I have always found that the loud belt whine was being produced by the balance shaft belt being adjusted to tight.

Boeing 717

I have read that several times as well but I am right on with the arnworx tool and it's pretty darn loose at that setting.

No.15

I had a hard time with the arnworx tool on mine. I could never seem to get a consistent reading.

For the roller on the balance belt, I used an old credit card to adjust the space and it seemed to work fine. My belt whine is gone