I have a '97 S-10 with big V6 and auto tranny. Somethning has started clunking around up under my dash on the right side. It sounds like it's inside the heater box. It does this periodically and spontaneously. Has a bit of a bellows or diaphragm sound to it, and maybe a flapper valve.
It just does this as I go along, for no apparent reason.
What is it telling me?
In article , RB ruminated:
Sounds like a vacuum motor is giving up the ghost. The General loves their crappy vacuum motors (rather than using solid cables or some other method of actuating flappers). If you stick your head up under there while the engine is running, can you hear a hissing sound? Does it make that bellows sound mostly when you step on the gas (thus reducing the vacuum provided by the engine)?
Of course, it could just be the flashlight in your glove compartment bouncing around on the whoopie cushion in your glove compartment:-).
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