Name that noise...

[rs_hunter]

My car has been squeak, rattle and clunk free until recently. Of late, I've noticed an intermittent rapping sound when starting the car from cold. It only happens perhaps one time out of ten, if not less frequently.

It starts with 5-6 quick knocks from the engine compartment and it sounds like they're occurring on the passenger's side. A few moments later, the 5-6 quick knocks are repeated inside the passenger cabin. The ones in the cabin seem to be coming from behind the driver's side knee bolster, behind and below the instrument binnacle.

Considering the number of people who've complained of noises, I figure someone's bound to have had this before. So, like the title says, name that noise...

 

[Unbelievable]

It starts with 5-6 quick knocks from the engine compartment and it sounds like they're occurring on the passenger's side. A few moments later, the 5-6 quick knocks are repeated inside the passenger cabin.

Is your cat missing?

 

[rs_hunter]

Is your cat missing?

Don't have a cat. But there are enough running around here to explain the number of times it has occurred. The time gap between occurrences would also allow for the cats to forget the last one that thought it would curl up and stay warm. Stupid felines, they still haven't learned that my Jack Russell Terrier will give 'em a good leg stretching every chance she gets...:biggrin:

 

[radiohead1075]

Fuel line rattle?

 

[rs_hunter]

Fuel line rattle?

I wondered about that, but I could swear the second part of the noise cycle is definitely inside the cabin. To those who've dealt with the fuel line rattle, did it sound like I described?

 

[def_KV]

sounds like knocking on a door

 

[Fivespeedg]

sounds like knocking on a door

My guess is something in the HVAC system. I think I've heard my car do it once before too.

 

[rs_hunter]

sounds like knocking on a door

Yeah, like 5 or 6 quick raps from inside the engine bay. Followed ~1-2 seconds later by the same occurring behind and below the instrument display, somewhere near the steering column. Does that seem right for the fuel-line issue?

I just can't get my mind around it sounding like the second part is in the interior. The inconsistency of its occurrence also seems strange. I've tried to pin down something that is constant from one time to the next, but I've yet to pinpoint anything.

Has anyone had the fuel-line rattle appear suddenly, having had no issue well into the car's life? I'm at ~18K, and until recently there were no noises whatsoever.

 

[rs_hunter]

My guess is something in the HVAC system. I think I've heard my car do it once before too.

The refrigerant lines are something that immediately came to mind when it started. IIRC, I've had it happen both with the climate-control on and off, though. I'm going to have to try changing the settings the next time it happens and see if it has any effect.

Who knows, I may have to begin starting the car while laying in the foot-well so I can see if I can feel something vibrating away up under the dash. That should look interesting to the neighbors...:biggrin: