Cadillac CTS-V Forum banner
1 - 19 of 19 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter · #1 ·
I have an idle knock that if you rev up the engine it disappears 2200-2400 and won't comeback until 1100rpm. It's annoying and embarrassing. Any ideas what this could be, I put a mechanics stethoscope on the snout, the valve covers, the lid, with nothing. Any ideas what my issue could be.
 

·
Premium Member
Joined
·
16,486 Posts
dang. knock is bad.

Could be the motor (tune, mechanical) or more likely something is loose and bouncing around on the accessory system.

I'd get a good flashlight and try to narrow it down by sound and visual. Take off the supercharger pulley before starting it back up and see how it goes.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #4 ·
dang. knock is bad.

Could be the motor (tune, mechanical) or more likely something is loose and bouncing around on the accessory system.

I'd get a good flashlight and try to narrow it down by sound and visual. Take off the supercharger pulley before starting it back up and see how it goes.
Can you run the car without the supercharger spinning?
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #6 ·
Yes you can. Regular ls3 at that point. Good way to find out if your isolator shit the bed.
I wasn't sure to be honest being a twin screw I thought it wouldn't flow enough air through it to sustain rpm
 

·
Premium Member
Joined
·
16,486 Posts
Get a breaker bar, release the tensioner on the left / passenger side of the engine accessories and try to remove the belt (so it doesn't get chewed up when you start it).

Look for loose pullies or idler pullies while you do it.

Then tell us what you find!

Sent from my SM-G991U1 using Tapatalk
 

·
Premium Member
2009 Sedan
Joined
·
762 Posts
10-4. I understand that. Take 20 minutes when you can, and figure that out, so everyone can help from there. 👍
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #15 ·
Pulled the belt, started it noise gone, found the cover to supercharger pulley loose, tighten it up and the noise is quieter now. Sounds more of the typical supercharger needing new bearings.
 

·
Registered
Joined
·
320 Posts
Pulled the belt, started it noise gone, found the cover to supercharger pulley loose, tighten it up and the noise is quieter now. Sounds more of the typical supercharger needing new bearings.
Isolator most likely bad. See if you’re covered for the warranty. 10yr/100k mi I do believe.
 

·
Registered
Joined
·
6 Posts
I feel ya BillyBV, I'm over warranty in years with only 56,xxx miles. But hey, we get to become more familiar with our machines by replacing that isolator. And if you're like me, when you set out to do a small job, "mission creep" sets in and you end up giving it the ol' "might as well take care of this too".
I also understand about delaying our own gratification so we can take care of the ones in our life. I just spent the last three weekends replacing the PCV system on my father's '96 Volvo turbo 5cyl.
 
1 - 19 of 19 Posts
Top