trying to figure my rattling noise!

[Spykem4e]

Hi guys,

I have an 05 Cadillac CTS 3,6L with 218 000 kms and sometimes, 80% of the time, there's this rattling noise coming from the hood when driving. The transmission is an automatic.

The rattle is present only when in drive, not in park or neutral.

Also, only present when light load between 28 km/h and 42 km/h.

Only present between rpm range: 1800 rpm and 2250 rpm. Below this, everything is fine. Higher than this, perfect!

Cadillac dealer test drove the car and said it was the timing chain slapping but it would have triggered the check engine light and trust me, I don't want to tear the engine apart to check if its the timing chain or not!

I don't loose any power at all.

There's no relation with the a/c on or off or when touching the brake pedal at the same time I press the accelerator between the range speed and rpm (tcc off and the rattle is still there).

The noise is almost the same as this or exactly the same but its not rattling when idling but it does sound very very very close to that:

http://www.youtube.com/watch?v=xBIJmEC80_4&feature=related

Any idea?

With windows closed I can hear it coming from the engine area. With the windows down, I hear it from the bottom of the car since I'm driving at the same time.

 

[05ChevyI5]

Check the hood rubber stops/bumpers. Mine were causing a rattle/squeak. Lube them.

 

[Kaboomba]

those little rattles can come from a number of different places. you might want to have a look at various underhood shrouds, housings, heat shields, etc. anywhere that two things could touch if they were to vibrate just right.

 

[Nick R]

Check the serpentine belt tensioner. Our mustang does this, IE at idle, with the A/C on though.

 

[Spykem4e]

Thanks guys! Its been a year now since this annoying rattle appears and its driving me crazy!

When the car is cold, there's no rattle at all!

Question for you guys: if it was the timing chain, with a long screw driver, I would be able to hear it when placing it on the engine, right? I've tried all around the place to find the rattle or the timing chain slapping with the screw driver on the engine and couldn't find anything. I compared the noise I was hearing with different engines and same ones and nothing unusual.

I've changed both serpentine belts and one tensioner. I think I would have to check all pulleys but the problem is that the noise only occurs when driving.

I thought it was a pinging issue but when letting the car on overdrive and giving gas it should ping but its not even at very low rpm...

All ideas are more than welcome!

Sooner or later, I'll find the noise or I'll sell the car lol

 

[bigmike]

I absolutely hate rattles. HATE them. DESPISE them. I'm like a pitt bull when it comes to them.

I tend to drive next to buildings to help diagnose these noises. You can typically find out if it is under the hood or suspension problems this way.

Have someone put the car in drive and check under the hood. Perhaps the load on the engine might produce the noise for you to investigate it.

Hood latches can noise as well.

It might be time to get a set of "ears."

http://www.brandsplace.com/tool-automotive-repair-noise-detection-stethoscopes.html

 

[Spykem4e]

Guys, here's the update!

One of the 3 timing chains is stretched so when its hot, the timing chain knocks on the cover.

I'll have my car by this friday (hope so) and the dealer will do everything. Total cost 1496$ CAN tax included (parts and labor). Not so bad! I thought it would be 1k$ more.

The limousine is suppose to pick me up in any minute to they can give me a rental until my car is fixed. Can't wait to see the rental!

Question, since I've never done any timing chain replacement on any car I've owned, what should they do when replacing timing chains? I mean, do they need to change the sprockets (hope so), are they going to change the engine oil and the oil filter? I'm going to ask them to change the spark plugs while at it.