Q: Knocking when starting from a cold start

asked by on September 22, 2016

When I crank my car first thing in the morning after setting all night there is a knocking sound for a few seconds. One mechanic said it was because the oil filter is a sideways one and it takes a second for the oil to get where it needs to be and my other mechanic said it may be the timing chains. Neither one of them can fix the timing chain because they don't have the equipment. But going to the dealer fills my soul with dread!!!! What's your opinion on the knocking. Oh yeah it's been knocking for several months- maybe even a year.....

My car has 120761 miles.
My car has an automatic transmission.

This is somewhat normal as the oil sits down in the oil pan when the car has sat for an extended period of time. When you first start it in the morning, it takes a bit of time for the oil pressure to build allowing the oil to circulate properly throughout the motor. This can cause a bit of knocking and is somewhat normal as long as it does not last too long and is not excessive.

Your vehicle is also equipped with something called a knock sensor which works similar to a microphone listening to the engine and sends signals back to the computer when there is excessive knocking detected. When this happens it retards the timing slightly as a means to protect the motor from potential damage. When this happens it will also trigger the Check Engine Light registering a fault code.

As mentioned above, as long as the knock does not last for an extended period of time, your car should be fine. If you’re avoiding the dealer and would like to have it looked at, consider YourMechanic, as one of our mobile technicians can come to you and diagnose the knocking sound firsthand.

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