EDenney

2000 C5. Original owner, and very trouble free over the years. I currently drive it short distances, maybe once or twice a week, but I've put over 110K miles on it over the years. Recently I noticed that a couple minutes after I started my car, after I backed out of my garage and was just starting to pull forward, a rather loud noise came from inside my engine compartment for about 5 seconds. It literally sounds like an air compressor turning on, I don't know how else to explain it.

Each time, it only did it when I was first starting my car for the day, and it didn't do it after I stopped somewhere and started up again. Today was the 3rd or 4th time I've driven my car since this started, and as expected it did it again just after I backed out of my garage and was about to go forward. However, it also did it right after I turned my car OFF after stopping somewhere, and again when I got home about 10 minutes later.

I opened my hood, turned my car on for several seconds, then turned it off, but it didn't do it. I then turned my car on, put it in gear, backed up about a foot, then forward about a foot, put my car in park then turned it off, and this time it made the noise again. My nephew was standing by the engine bay with the hood open to listen for it, and he said it sounds like it's coming from the right front area of the engine bay . I looked over there and I can't see anything I can imagine it would be, and I've never in my life heard this noise before from any car I've owned, so I'm baffled. I didn't notice any pumps in that area (though I could be wrong), and the closest thing I can see there that I can even possibly imagine might be capable of making such a noise, is the electric fan. If anyone has any experience with this problem, please let me know what you think it is and the best course of action. I may or may not be able to duplicate the problem and record it if need be.

Thanks

grantv

Video... please post one.

EDenney

I'll try tomorrow if I'm able to duplicate it.

leadfoot4

There an air pump, that's part of the anti-pollution equipment, that I just can't think of the correct term right now, located in the engine compartment, on the left side, next to the radiator. It pumps air into the exhaust manifolds, under certain conditions. Either it, or the "check valves" on the manifolds, could be malfunctioning.

3sACROWD

This is my thought too. For clarity, the left front is the driver's side. It is the AIR pump (Air Injection Reaction) Have you tried pulling codes?

EDenney

Thanks guys, it absolutely sounds like an air pump of sorts, but I never knew or imagined there was one in the engine compartment. The noise did sound like it was coming from closer to the front of the engine compartment, near the radiator, but my nephew (who was standing right there with the hood open) thought it sounded like it was coming from the passenger side up there. My car hasn't thrown any codes at all recently, so no, I didn't try pulling codes since this started, but I'll double check as soon as I can. Haven't had a chance today to try and duplicate it and/or get video/audio of it. If you heard it, I'm sure you'd all agree it sounds like an air pump for about 5 seconds, the only question is exactly where it's coming from, and what the nature of the problem could be. Sounds like someone has a couple ideas, but I'd like to narrow it down as much as possible, as well as the best course of action, other than just a blanket statement of take it to a dealership .

EDenney

I started this thread about 6 weeks ago, but never had a chance to look into this further or make a video as requested until now. I was able to determine where the noise is coming from today, it's from the right front headlight (or rather directly behind the headlight) right after the headlight goes down. I couldn't pinpoint this before because it only happens after my headlights go down (not as it goes down, or even after it comes up), and my headlights only come up if it's dark, and only if I put my car in gear. Once I knew where it was coming from, I was able to do a more specific search for C5 headlight noise and found a number of posts from people reporting the exact same problem. Apparently it's an issue with the gear, not the headlight motor. I'll post a link to the video I recorded of the noise (still sounds like an air compressor of the type you'd use to put air in your tire to me), and perhaps this thread will also help someone else in the future. Apparently RodneyDickman.com sells the gear kit, and there's a DIY guide for this repair somewhere in the forums.

mike venth

Have you check for any codes on the dIc? If its not working right, leaking air or the check valve's (L) (R) or both it should through a code..
mike v

sorry--should have finished rearing your post... lot of good info on gear repair's

EDenney

Thanks for the link Mike. Car never did throw any codes for this issue, but now that I know it's just a gear, that doesn't really surprise me. That vendor must sell a lot of these replacement kits, because it's the very top item when you go to his website.

DarthVetter5

my passenger headlight did the exact same thing. Bought the kit with hardened aluminum gear, grease and glue included. Took about 30-40mins per light. GM really cheaped out by using Nylon as a gear...