white smoke out exhaust

Reply Subscribe

Thread Tools

Search this Thread

Aug 7, 2013 | 07:03 AM

PurpleHaze9414

Thread Starter

On The Tree

Joined: Sep 2011

Posts: 115

Likes: 0

white smoke out exhaust

Anyone experience this when coming out of dod mode? My car has this happen... the car is also lagging then surging.... I recently got p0420 code maybe bad cat? I'm hoping not blown head gasket?

Aug 7, 2013 | 07:15 AM

crich88848

On The Tree

Joined: Dec 2012

Posts: 173

Likes: 3

From: Chattanooga, TN

Quote:

Originally Posted by PurpleHaze9414

Anyone experience this when coming out of dod mode? My car has this happen... the car is also lagging then surging.... I recently got p0420 code maybe bad cat? I'm hoping not blown head gasket?

Sounds like a blown head gasket. White smoke means you're burning water(coolant) typically. Is there any smoke coming out from anywhere under the hood? Are you sure the smoke isn't grey?

Last edited by crich88848; Aug 7, 2013 at 07:22 AM.

Aug 7, 2013 | 07:20 AM

PurpleHaze9414

Thread Starter

On The Tree

Joined: Sep 2011

Posts: 115

Likes: 0

I don't see smoke anywhere else it may be grey it shoots out a plume of smoke when on highway when I go from 4 cyl to 8 cyl mode

Aug 7, 2013 | 07:23 AM

crich88848

On The Tree

Joined: Dec 2012

Posts: 173

Likes: 3

From: Chattanooga, TN

Quote:

Originally Posted by PurpleHaze9414

I don't see smoke anywhere else it may be grey it shoots out a plume of smoke when on highway when I go from 4 cyl to 8 cyl mode

Grey smoke could mean you're just running lean.

Aug 7, 2013 | 07:25 AM

PurpleHaze9414

Thread Starter

On The Tree

Joined: Sep 2011

Posts: 115

Likes: 0

Possibly the p0420 is lean on bank 1 I'm hoping its a cat n not head gasket even though both are expensive

Aug 7, 2013 | 07:25 AM

crich88848

On The Tree

Joined: Dec 2012

Posts: 173

Likes: 3

From: Chattanooga, TN

Quote:

Originally Posted by PurpleHaze9414

I don't see smoke anywhere else it may be grey it shoots out a plume of smoke when on highway when I go from 4 cyl to 8 cyl mode

If it was a blown head gasket you would see smoke all the time, especially when your at a stop.

Aug 7, 2013 | 07:29 AM

crich88848

On The Tree

Joined: Dec 2012

Posts: 173

Likes: 3

From: Chattanooga, TN

Quote:

Originally Posted by PurpleHaze9414

Possibly the p0420 is lean on bank 1 I'm hoping its a cat n not head gasket even though both are expensive

I don't know much about the codes and what they mean. Hopefully someone else will chime in and help you out with that. But like I said, if it's only smoking on the highway when you switch from 4cyl to 8cyl it's unlikely to be a head gasket as those usually smoke all the time when bad.

Trending Topics

Disappointing Dyno Results

33

563
So GM / ACD is no longer an option for Oil Pressure Sending Units?

14

351
Oil Bypass Barbell

20

512
Help between two cams

8

280
Radiator Fitment

6

196

Aug 7, 2013 | 07:36 AM

x11 nut

12 Second Club

iTrader: (3)

Joined: Feb 2011

Posts: 383

Likes: 0

From: S. FL to Philly ??

Smoke only when going 4 cyl to 8 cyl mode is indicative of oil pooling on DOD cylinders and getting burned as soon as those cylinders ignite again. That's one of the bulletins on DOD/AFM LS motors - there is a GM service for it, but at home fix is easier/ cheaper = can of SeaFoam or STP equivalent in gas tank, suck a second can thru a vaccum line & watch the smoke show... Then change your oil. Keeping frequent oil changes and PVC oil separator will prevent it from happening again.