Q: Engine knocks, tailpipe blows white smoke

asked by on July 22, 2016

When I turn the engine on, the tailpipe blows white smoke out. The car is also shuddering. After I turn the engine off, it starts making a knocking noise. Is my engine going out or is it something else causing this?

Smoke from engine or exhaust Inspection $94.99 - $114.99 Get a Quote

Hello. There are a few things that can cause this. If the smoke is white then you may have a blown head gasket. This is a common failure on this vehicle, especially if it has ever overheated. If the smoke has a blue cast to it then it may have leaking valve stems seals.

I usually start by doing a compression test to see if there is an internal issue. If there is a compression problem then it is a head gasket problem. If the compression is fine then it will need new valve stem seals. Both cases will require some serious engine work be performed.

If you need to have this looked at, consider YourMechanic, as a certified mechanic can come to you home or office to diagnose the smoke and repair this.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

My truck shakes when i go 60 mph
Generally, if you feel a shake in the steering wheel, the problem is up front. If the shake is felt more in your seat, it's coming from the rear. Front possible causes: Out of balance or out of round tires....
Keep having to add coolant
Hello. If you keep having to add coolant to the engine then it may be possible that there is a coolant leak, or that the engine may be consuming it somehow. I would carefully inspect the engine for any signs...
Cracked Manifold
Hi and thanks for contacting YourMechanic. If there is a crack in the exhaust manifold, there will be a tick noise or a smell of exhaust emission under the car. For the jerking motion, that would have to do with...
why does the heated side mirror drivers side not work
Hi. There are a couple of reasons why your driver's side heated mirror is not working. The first thing that comes to mind is the fuse for the heated mirror has blown and is causing it not to work. Another...
Coolant level dropping quickly 2006 Saab 9-3
Hi there - yes, I would say this is a problem. Coolant loss (https://www.yourmechanic.com/question/my-car-has-a-coolant-leak) can be deceptive - failing water pumps will sometimes only leak while running, blown head gaskets can leak into the engine crankcase, turning the engine oil...
How much for an oil change, battery change and alignment cost?
Billing question sent to CS for the cost of replacing the battery, changing the engine oil, and performing an alignment.
I accidentally put washer fluid into the coolant Reservoir. what harm can this cause? it was about 3/4 of the bottle.
Hello, yes this can break down the coolant and it can become acidic. The coolant system will need to be flushed. If you'd like, a certified Your Mechanic Technician can come to your location to perform this. Please look at...
03 buick lasebre custom
Hi There, It sounds like you may have a dirty or failing idle air control valve causing your engine idle to fluctuate. The idle air control valve (https://www.yourmechanic.com/services/idle-control-valve-replacement) is a small valve on the engine's intake system that reads the...
I have a CLS550 I was driving on the Interstate and Suddenly my car gave me a message saying pull over stop driving car too low wh
Hi there. This error message typically comes on when there is a leak in the air suspension of the Mercedes-Benz CLS-550. If you'd like to have one of our mobile mechanics come to your location and complete a suspension inspection,...

Related articles

What Does "Twin-Cam" Mean?
Twin-cam engines use two camshafts to operate the intake and exhaust valves. DOHC engines often have better power and efficiency than SOHC engines.
BMW Certified Pre-Owned (CPO) Car Program
Shopping Shopping for a used BMW vehicle often leads many drivers to consider certified pre-owned options. BMW is one of many manufacturers that have a certified pre-owned (CPO) program. Each car manufacturer structures their CPO program differently; read on to...
How to Troubleshoot a Small Engine Problem
Small car engines need attention if the car won't start, there's a loss of power, the car stalls or overheats, or if the car backfires.