Cadillac Owners Forum banner

1 - 20 of 78 Posts

·
Registered
2012 CTSV coupe
Joined
·
1,585 Posts
Discussion Starter #1
Just got my V out of storage was driving around a bit. Nothing too crazy. Some spirited driving. Then started to hear some knocking at idle. Took it to a very experience mechanic and he said to continue to drive it normal until bringing it in this Friday. He said its normal LS motor noise from sitting in storage. That an oil change and some " Sea Foam " (ive used this before... good stuff) in the gas tank will clean things up and take away the noise. Does this sound like solid advice to anyone.

He listened to the noise stepped on the gas a little bit. As the RPMs came off idle the knock went away. He seemed very confident in his diagnosis. Im just very nervous about it and driving around just doesnt seem right.
 

·
Registered
2012 CTSV coupe
Joined
·
1,585 Posts
Discussion Starter #3
No. Its not the supercharger. Its only at idle. It doesn't get louder with RPMs.
 

·
Registered
2010 CTS-V 6MN Thunder Gray; 07 SRX AWD N*;
Joined
·
1,219 Posts
Piston slap?
A very common characteristic with LSx engines on start up and at idle going back to the LS1. I had it on my '98 Camaro SS. There is a ton of info out there on it and the bottom line it seems, is that it's harmless and disappears after a short while. It definitely was a cause for a lot of concern at the time... if it was me, I'd go with your mechanic's diagnosis. The noise never caused a problem for me.

Best regards,

Elie
 

·
Registered
Joined
·
277 Posts
That an oil change and some " Sea Foam " (ive used this before... good stuff) in the gas tank will clean things up and take away the noise.
Putting it in the gas tank will address fuel system and upper cylinder issues. If you want to address noisy lifters, it needs to go into the crankcase.
 

·
Registered
2012 CTSV coupe
Joined
·
1,585 Posts
Discussion Starter #6
Piston slap?
A very common characteristic with LSx engines on start up and at idle going back to the LS1. I had it on my '98 Camaro SS. There is a ton of info out there on it and the bottom line it seems, is that it's harmless and disappears after a short while. It definitely was a cause for a lot of concern at the time... if it was me, I'd go with your mechanic's diagnosis. The noise never caused a problem for me.

Best regards,

Elie
But it doesnt go away after awhile. It only goes away with slightly above ide RPM. On initial cold start its not there. Then it slowly comes in as it warms up. Then its always there while at idle. Loud enough you can hear it in the cabin. Are you saying after an oil change and a few days driving it will go away?
 

·
Registered
2009 CTS-V
Joined
·
2,840 Posts
garfin said:
Piston slap? A very common characteristic with LSx engines on start up and at idle going back to the LS1. I had it on my '98 Camaro SS.
And I on my '99. That's a term I've not heard in a long time! Thanks for the flashback! Much like you, I think it'll clear. I thought Seafoam was injected into the intake? Maybe there's a tank additive but I'd never heard of it until now.
 

·
Registered
2012 CTSV coupe
Joined
·
1,585 Posts
Discussion Starter #8
And I on my '99. That's a term I've not heard in a long time! Thanks for the flashback! Much like you, I think it'll clear. I thought Seafoam was injected into the intake? Maybe there's a tank additive but I'd never heard of it until now.
Oh. I only know about the tank additive. There is an intake additive too?
 

·
Registered
2010 CTS-V 6MN Thunder Gray; 07 SRX AWD N*;
Joined
·
1,219 Posts
But it doesnt go away after awhile. It only goes away with slightly above ide RPM. On initial cold start its not there. Then it slowly comes in as it warms up. Then its always there while at idle. Loud enough you can hear it in the cabin. Are you saying after an oil change and a few days driving it will go away?
What you're describing in the highlighted text above sounds exactly like the opposite of what I would have called "piston slap". It was there on cold startup and would disappear after a minute or 2 as the engine warmed up.
Sorry for any confusion...

Best regards,

Elie
 

·
Registered
2009 CTS-V
Joined
·
2,840 Posts
CavemanB52 said:
Oh. I only know about the tank additive. There is an intake additive too?
In my F-body days it was introduced into the intake. Always made me leery. Never did it. That is unless there has always been two applications and I only knew about one.
 

·
Registered
2012 CTSV coupe
Joined
·
1,585 Posts
Discussion Starter #11
Well... either way. Ill let you all know how it goes. Im being told i have typical LS motor noise from putting it in storage with used oil then not changing the oil right away and driving it causing old oil to make my valve train sticky witch is making noise at idle. He said ounce i can get it cleaned up it will be fine. Stay tuned if you're interested.
 

·
Registered
'14 CTS-V LongRoof; '16 ATS-V Sedan,' 04 Trailblazer 4x4; '10 CTS LongRoof gone but never forgotten
Joined
·
14,171 Posts
I used to lay up my MGB in the northern winters. I changed the oil and put in cheap stuff at the end of the season. When I took it out of storage I would put in my "special" oil for driving season.
 

·
Registered
2012 CTSV coupe
Joined
·
1,585 Posts
Discussion Starter #13
I used to lay up my MGB in the northern winters. I changed the oil and put in cheap stuff at the end of the season. When I took it out of storage I would put in my "special" oil for driving season.
I should have read up on storage a bit more. All i did was put it on a batter tender and put irish spring soap under the hood to keep the mice away.
 

·
Registered
'14 CTS-V LongRoof; '16 ATS-V Sedan,' 04 Trailblazer 4x4; '10 CTS LongRoof gone but never forgotten
Joined
·
14,171 Posts
Also put something in the cabin to keep rodents out. They can find a way into the cabin even though you may not think there is a way! I have read horror stories.
 

·
Registered
Gone; ‘09 V, ‘13 V coupe. Curr; ‘14 PG Vsport prem w/Kona interior
Joined
·
6,177 Posts
I should have read up on storage a bit more. All i did was put it on a batter tender and put irish spring soap under the hood to keep the mice away.
Why Irish Spring? Do mice prefer Dove?
Just kidding, thanks for the education. I had never heard of this before now. I googled it, and sure enough its for real!
My day has not been wasted. :)
 
1 - 20 of 78 Posts
Top