View Full Version : Why do my cats smoke?

Mr. Snake Car
11-11-2006, 05:25 PM
I have smoke coming from my cats. I noticed a smell similar to rubber/oil coming from the car. After a short drive this afternoon I poked my head under the underside and noticed that both catalytic converters were smoking. Not really bad but I could see white whisps swirling from both. :(

11-13-2006, 06:09 AM
My guess is that what ever is causing the smoke is external to the cats. Best to look at the underside of the vehicle while the front end is on jack stands to track down the source. If it only occurs on the drivers side, inspect brake master cylinder and resivior for the source as well as the main feed lines from the master cylinder for leaks, May also be a valve cover gasket leak or power steering overflow or leak. It could also be from coolant if it vents out from the pressure cap. If on the passenger side valve cover, or AC refrigerant may be the cause. Also sometimes the transmissions develop a leak at the output shaft which would be noticed by a film of fluid sprayed from the yoke of the drive shaft. It very well could be from an external source that was splashed up from the front wheels and got trapped under the heat shield. You may also want to check the inside lip of the wheels for brake fluid leaking since that will also be thrown out. It may be nothing to be concerned with or cause by a small leak of some sort. The other thoughts would be that you have a small leak on one of the welds on the cats if they were running cherry red which would indicate a lean condition or oil contamination inside the cats if clogged would create a large issue. Some aftermarket tunes (SCT) if not custom may run the A/F on a flat line in the upper RPM range, this should not pose much of a risk but may cause the cats to overheat. The factory tune will compensate and enrich the A/F in the upper RPM band to cool the cats down. It may not be anything to worry about unless it continues every time you drive the car.

11-13-2006, 01:32 PM
they were getting it on pretty good......oh wait, catalytic converters:rotf: sorry

11-15-2006, 06:39 AM
they were getting it on pretty good......oh wait, catalytic converters:rotf: sorry