My c6 whistles?

[bucholzi]

On my 89 F250 7.3, the c6 whistles in 1. and later also in 2. gear. The sound has become progressively worse and only included 2. most recently. The sound is distinctively stronger in 1. gear. It shifts fine (that is, it shifts at a bit high RPM's but I blame that on the vacuum modulator, i think it's for a gasser: green stripe?). I'm wondering if it could be an internal leakage, is there any actions I might try with the tranny still in the vehicle? I have changed filter and oil, and checked for vacuum leaks.

Thanks,
Simen

 

[gonecrazyi]

My c6 on my 80 inline six motor always whistled in first gear, It really wasnt noticible until the motor was under load. But I paid no attention to it and drove it for another 50,000 miles before scraping it. In total the truck had well over 350,000 miles on har and all original.

 

[Petri317]

When I had my truck, it whistled especially loud in third gear. I was told it was the torque converter. It was the original 16X,*** mile transmission. The sound didn't affect operation of the transmission, and the fluid never smelled burnt, so I didn't worry about it.

 

[k_williams1982]

On my 89 F250 7.3, the c6 whistles in 1. and later also in 2. gear. The sound has become progressively worse and only included 2. most recently. The sound is distinctively stronger in 1. gear. It shifts fine (that is, it shifts at a bit high RPM's but I blame that on the vacuum modulator, i think it's for a gasser: green stripe?). I'm wondering if it could be an internal leakage, is there any actions I might try with the tranny still in the vehicle? I have changed filter and oil, and checked for vacuum leaks.

Thanks,
Simen

My vac modulator has a green stripe and the one that was on the transmission before had a green stripe too (That's why I bought the current green striped vac modulator) and mine tries to shift out of first a little too soon. From what I've read about these vac operated C6 transmissions is that if there is a vac leak from the vac control on the IP to the trans or the vac controller on the IP is faulty/out of adjustment, it will cause transmission to shift at higher rpm's. The original modulator on my C6 was non-adjustable, but my current modulator has a slotted screw inside to connection for the vac hose that will allow me to adjust it to control the shifting a little better.