I was told I have a rod bearing going out because of the knock in my engine. How do I find out which rod bearing it is and how do i replace it with the engine in the car?

1. For find out which rod bearing is out of order you need to use an engine stethoscope.
2. You can replace the bad rod bearing with the engine in the car, by removing the oil pan and the cylinder head. I strongly recommend you to replace all rod bearings of the engine, (one complete kit).

Duane Wong

One could use a stethoscope, but this would not isolate the knock as coming from any particular cylinder except it would get louder the closer one would probe at the bottom of the engine.

I would say that an overhaul of the engine is in order, in which case, the rebuilder would be able to identify the bad rod bearing when changing the piston rod bearings out.

I'm afraid that the usual procedure is to take the cylinder head off and take the pistons out after removing the two bolts that hold each piston rod to the crankshaft.

This is a major job which requires pulling the head and the oil pan off, which is actually most of the engine.

Good luck on this repair.

Duane Wong

There's an idea, if you would remove the spark plug from each cylinder, the noise should change if it has less pressure on the piston.

I could copy and paste some of the procedure on fixya.com if yo provided the year, make, and model of the vehicle as well as the engine size.

However, the procedure is so long, that I doubt it will fit into the page.

I would purchase the service manual from Chilton or Haynes and/or the factory repair manual in order to get a clear picture of what is involved.

It is considered a major repair that requires special tools and know how.

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Fundamentally, you're right, the bearing failure is one that is simple. But, the procedure to do fix it is quite lengthy, in my experience, to do the job right.

Good luck.

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