96 Lumina Van Noise in Transmission

[Brian J]

I have a 96 Lumina Van, 3400, 145k on it. Recently I noticed a noise coming from under the hood, thought it was something tied in to the drive belt first so I took it off and found out it wasn't coming from that side of the engine. It sounds like it is coming from the right side, transmission side. It shifts great, no problems there YET, I have noticed that this squeel eases up when I put a load on the transmission but when it levels out it comes back. Any input would be greatly appreciated.

Thanks,
Brian J

[jeffcoslacker]

Over the last few months of reading these posts, I've noticed a pattern of complaints that seem to involve a light wheezing or high pitched fizzing sound coming from the tranny side of the engine compartment on these, that seems to sometimes trace back to the vacuum modulator on the tranny sucking fluid through a blown diapragm. When you give it throttle, vacuum drops, which would explain why you hear it better without load. Think maybe?

[Brian J]

Jeff that does make sense, because other than the noise the van shifts great, lots of power and torque. Now where is this vacuum modulator located?

[troy1]

if the mod is bad take if off and see if there is tranny fuild coming out the the side with the vacuum line hooked up to it some time you got to take it off and tip it down to check it if the mod is bad you sould have a 1-2 slide bump shift

[jeffcoslacker]

Pull the vacuum line off, and see if there is evidence of tranny fluid in there. Usually, if the diaphragm is blown, it will cause a situation where it wants to hold first gear until you abruptly drop the throttle, but if the perforation is very small, the small amount of fluid being sucked through overcomes the loss of vacuum, and it will work right until the hole gets larger. You might want to let it sit at idle for some time before checking it, that way it will have drawn a large amount through, without sucking it through to the motor, and will be easier to notice.