Skip the auto shop - Our mechanics make house calls

Q: Engine knocks, tailpipe blows white smoke

asked by on

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?

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Engine knocks, tailpipe blows white smoke

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

Get a quote

What others are asking

Q: Noise when a 2015 vehicle is started

It's a 2015, so it should still be under warranty. Take it back to the dealer and let them fix it for free. If it's cranking and not starting, and it's a 2015, then that's not your problem. Let the...

Q: Right low beam malfunction

Your car will test all the light circuits when you start the car and will let you know when there is a problem. Your low beam headlight is out due to a bad bulb and I would recommend replacing both...

Q: Loss of power and misfiring in 2000 BMW 323CI

The first thing you want to check is on the driver's side, the intake manifold and all the plastic there is between the radiator and the engine. You may barely even see them without a flashlight and a little mirror....

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...