Manning

Just for giggles, let's suppose an engine was developing rod bearing issues. When would you start to be able to tell? Sparkly oil drains out of the pan during an oil change? Distinct sound while engine is running? And when would you hear the sound, all the time, under load, idling, at shut down?

Just wondering

Campeck

all the time. and it sounds like...knocking...

Uranium-235

I had an old Pontiac with bad bearings - you'd hear it at idle, then it would go away as the engine speed increased. Probably depends on the extent of the damage.

MM951

rod knock should increase with revs

its pretty obvious when you have it...

Manning

Always always? I know what it sounds like, but I have only heard it on motors that had it pretty bad. I was wondering if there is a particular instance when it would occur in the the early stages.

Legoland951

Rod knocks get louder as the car is warmed up due to lower oil viscosity at higher temperatures. Higher revs should make the knock sound louder especially under low RPM high loads.

Manning

Yeah, we had an old Camero that had bad bearing, but I didn't start driving it until they were pretty bad and you could hear it clunk, clunk, clunking at most engine speeds. I was interested in what you described though as I would expect that as wear first allowed knock it would only be apparent at particular loads or speeds.

Mighty Shilling

When mine went, it could be heard at idle, sounded like a bad lifter...but a little louder... then, on the freeway, it got louder... then it finally ate itself, and was VERY loud at idle... ya know the sound of a bad engine in the movies, with the knocking every so often? yeah... it sounds like that...

and my oil wasn't sparkly, it was chunky...

BlueRiver86

When the bearings went in my Camaro it was very subtle under idle, but once you got on it you could hear the tapping, its unmistakable.

Manning

So you had to use a spoon or a fork?

Mighty Shilling

fork...