Hello everyone,

I have a 1995 Z-28 with ~200K on it. In the last month, it's developed a whining sound at idle. The sound varies in pitch with RPM and seems to be coming from where the rubber air intake meets the throttle body (assuming that's what this is even called on this model).

Engine performance seems unaffected by this development, but I'm naturally concerned. 'Funny' noises from an engine compartment usually don't end up being too funny!

I'd appreciate any suggestions as to what this might be.

Thanks in advance,

Christian Tobler

Hello everyone,

I have a 1995 Z-28 with ~200K on it. In the last month, it's developed a whining sound at idle. The sound varies in pitch with RPM and seems to be coming from where the rubber air intake meets the throttle body (assuming that's what this is even called on this model).

Engine performance seems unaffected by this development, but I'm naturally concerned. 'Funny' noises from an engine compartment usually don't end up being too funny!

I'd appreciate any suggestions as to what this might be.

Thanks in advance,

Christian Tobler

I would think the power steering pump or AC Compressor would be the most likely culprit.

Does it make this noise in and out of gear?

Hello,

Yes, it's happening in and out of gear. The sound is unaffected by whether or not the AC's running or if the wheel is turned or not.

It sounds like it's right at the forward part of the throttle body. I pushed on the rubber air intake and that seems to change the pitch of the sound, though I couldn't always get that result consistently.

Thanks,

CHT

I just went through something like this on the wifes 06 Trailblazer. I found the idler pulley bearing dry... injected grease through the seal and worked the bearing.... all is good again :D

is there any radio feedback?

It could also be an alternator whine which they typically make before they go out.

Belts? :confused:

Belts? :confused:

The pulley suggestion is very valid, I cant remember my LT1 that well, but you could confirm that the noise is coming from a driven accessory by starting without the belt(s) and running to see if the whine is caused by a pulley or driven accessory. More worryingly is if it could be the cam driven water pump.

I can't think of what would be whining in the throttle body except a failing injector or IAC motor, but in those cases you would definitely see a change in performance.

Thanks much folks,

I listened a bit more carefully just now and I am starting to suspect it's the pulley or, more likely, the alternator. It's tricky to hear exactly where it's coming from.

It's the original alternator, so it should about time for it to go...

Thanks again!

All the best,

Christian

I'd also pick up a new Gaterback serpentine belt to go with the replacement alternator:yes::thumbsup:

I had a whine on my 96RS. I thought it was the ps pump but it was the water pump. I replaced the water pump, no more whine.