: Loud snapping sound during startup/shutdown



csbacchus
09-29-05, 07:07 AM
What is this noise? It sounds almost like the hammer on a gun during a dry fire. A very loud, distinct metallic SNAP during startup/shutdown on my '95 STS.

There are no codes, no discernable issues with the car, but I'm curious what this noise is.

Any ideas?

mcowden
09-29-05, 12:15 PM
What is this noise? It sounds almost like the hammer on a gun during a dry fire. A very loud, distinct metallic SNAP during startup/shutdown on my '95 STS.

There are no codes, no discernable issues with the car, but I'm curious what this noise is.

Any ideas?

Try and isolate where it's coming from. Have someone else start or shut off the car while you listen with the hood open. Is it coming from near the firewall? Near the accessory drive belt? Near the intake? Near the brake booster? Front of the engine? Rear? There are lots of possibilities and I've never heard of a noise like that before, so I think you'll have to tell us where it's coming from. My first guess would be an idle air control valve, EVAP purge valve, or EGR. Depends on where it's coming from.

jackc
09-29-05, 05:40 PM
I was getting a noise like that on my 93 before I changed my motor mounts. Usually just after start-up.

I haven't heard it since I changed them.

May want to check yours.

dkozloski
09-29-05, 06:14 PM
Motor mounts or torque strut. Have somebody else start it up and shut it down while you look under the hood.