Q: My car developed a very loud knocking sound.

asked by on October 29, 2016

I have car that developed a loud knocking sound. I don't really know what it is, I was told it could be a rod or the rocker arm but I don't know how to get to them. Can I get to it without taking apart to much of the car?

My car has 175000 miles.
My car has an automatic transmission.

It is possible the valve lifters are starved of oil due to a failure in the rocker arm. There are reported cases where the rocker dowel pins shear off. A direct consequence of that is oil starvation as the oil holes get covered. The rocker arms are part of the cylinder head assembly, so it is an on the vehicle repair and YourMechanic specialists, depending on your region, will be able to complete the work. Just to make sure that it is an internal engine noise, you can disconnect (briefly) the serpentine belt that drives all of the accessories and see if, by chance, the noise goes away (just in case it’s a failing alternator pulley bearing for example). It sure sounds like a valve lifter oil starvation issue though.

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