After several weeks of trial and errors, I was able to fix a rattling noise which has bothered me and my '01 C5 for almost a year.

Typical symptom was a brief clanking noise coming from the engine firewall area at low engine rpm (~ 1,500 rpm), typically when getting off on 1st gear. Problem was more frequent when engine was hot, ie during the summer season or when stuck in traffic.

Long story short, I eventually spotted the noise coming from the steel secondary AIR tee (item # 5 on the part diagram) which was hitting a blue stud protruding from the engine wall. It is not easily visible, you need to take a flash light and look at the area behind the brake boost unit.

During normal usage, there is sufficient clearance between the stud and the pipe. However, at low rpm the tee assembly will starting ringing and hit the stud. I was able to simulate it by moving the pipe with my hand.

I fixed the problem by slicing along its axis a 3-inch long 5/8" heater hose and then sliding it over the pipe where it hit the stud. Did it 3 weeks ago, and no more noise since then, while I could hear it daily before the fix.

Hope it will help those who had the same problem.

JM.

 

Nicely done. Although I don't have any rattles on my 04. my 96 rattled like crazy and took me a long time to track down most of them. Never could stop them all.

 

Good job! Rattles can be a bitch to find. I have been chasing one that is in the back of the car for a year now.