Knocking sound

[AJxtcman]

You have to be kidding me.
This is funny. WOW

I have been fixing that for a year.
Believe it or not your car is Farting
Your car has a Vent valve. This vents the gas tank. If you have pressure in the tank it will exhaust it. The noise is the Solenoid part of the valve.


This is just listed under an 06, but come on if it fits the Description get it replaced.
TSB #06-06-04-062 - (11/27/2006)
Models: 2006 Cadillac DTS
Subject: Knocking Noise That Repeats Three Times on Cold Start (Install New EVAP Canister Vent Solenoid Valve)

Important: The noise emitted from the evaporative emissions vent solenoid is not indicative of any condition with the solenoid or the customer's vehicle. Please inform your customer that the sound heard is the result of the valve cycling during a required emissions test. If the knowledge that the vehicle is operating properly relieves the customer concern, DO NOT replace the EVAP solenoid. If the customer expresses that the noise is offensive, replace the EVAP solenoid with a newly available and quieter operating solenoid using the procedure in this bulletin.

Condition
Some customers may comment on a knocking noise heard from the rear area of the vehicle. The knocking noise occurs three times after a cold start up and usually while driving the vehicle under 16 km/h (10 mph).

Cause
The EVAP emission system performs a series of tests upon cold start up to ensure that the EVAP system is operating normally. The EVAP canister vent solenoid valve will purge and cycle the solenoid causing a noise that might be heard inside the vehicle and perceived as a knocking noise.

[AJxtcman]

Patent owners here

[cubldr]

Mine "knocks" exactly five times each and every time, about a mile from the house on cool to cold mornings. Not on warm-to hot mornings. It also knocks about 3 times about 3-4 minutes after I turn the car off in cool weather. Is this also a function of this same "issue"?

[rollindts]

Originally Posted by AJxtcman

If the knowledge that the vehicle is operating properly relieves the customer concern, DO NOT replace the EVAP solenoid. If the customer expresses that the noise is offensive, replace the EVAP solenoid with a newly available and quieter operating solenoid using the procedure in this bulletin.

That they would even WRITE that into the bulletin makes me want to..

just goes to show that you got to yell and scream at the dealer before they bend over backwards to fix something

[30+MrGAS]

same on my 2007 DTS...in old days we used to have similar noise caused by electric fuel pump in rear....

[cubldr]

Originally Posted by 30+MrGAS

same on my 2007 DTS...in old days we used to have similar noise caused by electric fuel pump in rear....

I once had a 1969 Datsun 2000 Roadster (looked sorta like an early 70's MGB) that had a fuel pump in the rear and you are right. It sounded very similar to this issue.

[pompste]

Originally Posted by mack1a

If I had a product on the market and it had a user forum like this I would be reading the SOB every day and learning how my product was doing, what people like and what they dislike. I would learn from it, I would make product improvements because of it and I would look for repeat issues such as this knocking sound. If someone who gave a rats ass read this thing they would realize that several people are experiencing this stupid knocking sound issue. If I had an entry level former East German car I would want that knocking sound fixed.

If anyone from GM looks at things here I would be delighted if they would call or e-mail me.

Otherwise, I will take this thing to the dealer until I hit the magic lemon law numbers then I will win the case, get my money back and go away.

Dude,you are 100% correct.Cadillac engineers should be reading the information on this site daily to prevent problems from happening in the first place and for product improvements.

[mikeythegreek]

I used to have this happen on the coldest morning, and being in South Philadelphia you better believe i looked around for someone tapping on my car. But honestly I havent heard it in the longest time. Ive been more consistent in the gas I use now then i was before. Since GM prefers you use top tier i make it a point to get top tier. In this area pretty much Shell is the way to go. But it has definitely been a while since Ive heard.

[Andy1]

My 06 DTS does the 4 knocks routine too. Has since new. I have been told it is the air compressor (under the car, under the back seat) for the rear air shocks, releasing air.
Andy1

[cubldr]

It's a cold weather thing. Mine does it routinely in cold weather and stops when it warms up, like 103 freakin' degrees here in NC this past week, with comparable humidity.

I know you TX guys think we're amateurs. I just can't take it anymore.

You know it's hot outside when you leave the A/C on your Caddy seats turned to high four hours at the time on the road and your hindquarters don't freeze up.