Woodman71

Short drive this morning. Just for fun (and paranoia) I had a listen to the running engine. Heard what sounded like a fast paced ticking sound under the lid.

Opened it up, sounds like it was coming from near the alternator and/or serpentine belt.

Any internet diagnoses from the well educated folks on this forum?

5CHN3LL

5CHN3LL

Turn off the car, remove the serp. belt, and start the car again (briefly). If the sound is still present, you know it's not one of the accessories. If the sound is gone, shut the car back off and spin each accessory (and pulley) by hand to see if you can identify which one might be acting up.

5CHN3LL

Note that you may not hear the sound he's describing on computer speakers - I could only hear it when I switched to headphones. It sounds much too fast to be an accessory - it's a high-pitched clicking at - guessing - 3-5 hz. Almost like a tazer. Weird.

Woodman71

Thanks 5CHN3LL, that is spot on. Fast and high pitched.

5CHN3LL

Fuel injector?

Woodman71

Could be I guess. Almost sounds more electric though, a buzzing sound.

EDIT: Found a note from Jake last year that said:

"I pay more attention to the rhythm of the noise than anything else.

Lots of the small ticks that are heard rapidly as from fuel injectors. DFI engines have very loud injectors.

One thing is for sure, within an engine no noise is a good noise."

So perhaps the injectors. Small rapid ticks!

Ahsai

That's the evap purge valve clicking, right above the alternator. Just unplug it and the noise should be gone.

Woodman71

Thanks Ahsai, much appreciated!

Sounds like it's nothing to worry about then.

Ahsai

You could try to unplug that valve when you hear the clicking noise. Will only take a minute and then you can be sure.

Woodman71

Will do. Assuming the noise stops - is it a normal sound for that valve, or does it signify some form of failure? Thanks again.

DBJoe996

I agree completely. It should only "run" upon initial start. Meant to clear collected fumes in the evap system that collects while the car is sitting and not running.

Woodman71

Well that's no bueno, as it was after I'd driven about 4 miles.

Ahsai

If the noise stops after you unplug it, there's nothing to worry about. The dme will likely code if there's a problem.

DBJoe996

Actually, I was a little bit wrong on that - In modern cars, the purge valve is an electrically-operated solenoid, that is controlled by the engine computer. When the engine is off, the purge valve is closed. When the engine is running and fully warmed up, the engine computer gradually opens the purge valve to allow some amount of fuel vapor to be moved from the charcoal canister to be burned in the engine. The purge flow is monitored by a number of sensors. If the purge flow is less or more than is expected under the conditions, the computer illuminates the "Check Engine" light.