Q: Engine knock and bad sounds on start

asked by on

Whenever I start up my 2007 Toyota Tundra in the cold there is a kind of knocking in the engine. The first time I heard this I had it checked out and the mechanic said it was “piston slap." Not sure how worried I should be about this problem, engine is running fine 99% of the time. This truck has 70,000 miles on it, is it time to be worried?

Since you describe your issue happening when you first start it cold, I’m assuming the noise goes away shortly after starting. When your engine is running, the internal components are literally floating on oil that is constantly pumped and supplied to them and fill micro spaces. When your engine has been sitting for a while and gets cold, it is enough time for the oil to drain down and out of the passages. When you first start your engine after this, there is a brief time where the micro spaces have no oil pressure, only residual oil. If a part is worn enough it can exhibit a knocking or tapping sound until the oil pressure overcomes it, once again filling the gaps. If the knocking sound you’re experiencing goes away after starting, I would recommend a compatible oil additive. This may improve the situation. It is noteworthy however, that Toyota considers the knocking sound to be “normal”.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Engine knock and bad sounds on start

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: I'm wondering where my neutral safety switch is

On most models, Toyota locates the neutral safety switch on the transmission itself, adjacent to the shifter cable. If you end up needing some help for the job, consider YourMechanic, as a certified technician can help you replace your...

Q: noise from front side of driver seat

Hello. If I had a description of the noise it would help me to diagnose what the noise is. On a Toyota Corolla, there are common issues with the engine mounts that will cause noise as well as a failing...

Q: The middle leaf spring broke on a 2011 Tundra

Tape isn't going to hold it. There's a lot of tension on those and the only thing you do is replace them. The only place that sells them as far as I know is Toyota and they'll be super expensive....

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...