Bad connecting rod bearing - How would you know?

[saxontaylor]

If you experts could comment for my education....I saw a car on "Bimmers.com" that stated: bad con-rod bearing. My question is: how would you make that diagnosis? Would you not have to have torn into the bottom end to know this? and it you're already there why not fix it?

Help me to understand!

Thanks, Mark T.

[Guest Anonymous]

Bad connecting rod bearings manifest with a knocking sound. If it is very minor (just starting) it will sometimes be quiet on a cold engine and start to get louder as the engine warms up.

Typically the knocking will increase as the engine speed increases.

Either way the motor will require some rod and crank work.

some people will simply replace the rod bearings in an effort to fix - this will not cure anything only make it quieter and potentially even cause more marm to the motor.

As the rod begins to know your connecting rod will lose its round shape and begine to ovalize.

[polloelastico]

Interesting thread. I just noticed a knocking sound at idle myself, however, if I increase the RPMs just slightly it goes away.

[Guest Anonymous]

If it goes away you are probably OK.

[Guest Anonymous]

fuel pump knocks

other things apparently "knock"

get along skinny 3/8 extension apiece of hose that fits the round end , push hose on , put square end on different parts of the motor to locate the source of the knock

Rods will be block . louder lower on the block.

i found a fuel pump and a modified air cleaner were hammering like hell easy fix

[BrianC]

If it goes away you are probably OK.

Is that like turning the radio up so you dont hear it as much?

hehe

[Guest Anonymous]

He he let me clarify,

If it goes away when you rev the car you probably don't have a bad rod bearing, in my experience.

I have had 2 m10's succumb to rod knock and you kind of know it when you got it, kind of like the rash you got in University.

[Napes]

in the side of the block, one that definitely effects designed operation.