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How to determine when you are about to throw a piston rod?

When you believe you have a decaying piston rod in a straight 4 engine, what are some signs that you might throw the rod soon? What RPM number is safe to stay under to reduce pressure on the rod?

Public Comments

1. A lower end knock. There is no safe rpm once the rod end is damaged. But lower rpm's might get you by. Put a quart of 90wt gear oil in it and it may allow you to get by but the longer your drive it the more damage is done
2. You could throw a rod at idle if there is damage to the rod bearings, or wrist pins. If it already knocks, expect it to go.
3. you will hear a ticking noise coming from your engine and the noise wont go away, to fix the noise you have to take your entire engine apart and replace the bearing. Regardless of what you do don't rev your engine to high or you'll through your piston rod right through your engine and then you'll have problems
4. listen for a knock that speeds up with rpm. there is no safe rpm if its knockin its done
5. You will hear a loud knocking sound . There is no save RPM if you hear this sound. Shut it down and get it fixed before you put a hole in the block.
6. The knocking noise is the first sign, might have some lose of power. The rpms aren't going to matter much if the piston rod is that far gone. Sure the higher the rpms the worse it will be when it does go. Plus the longer you drive it the worst the damage. Like pulling back a rubber band the farther you pull it the farther its going to go so look out block. By now the rod bearings and the crank may be shot. Only your mechanic will know if its torn down.
7. there is no safe rpm if it is a rod n u keep driving it until it comes aloose u almost cert going 2 damage the engine block u already have crank shaft damage but the more u drive it the worse damage u r going 2 do 2 the engine if u get it repaired now the block has prob not gotten damaged yet and the crank shaft can prob b turned if u r trying 2 just get it 2 limp round 4 few days try a quart r2 of gear oil 90 wt n try 2 stay at as low rpm as u can good luck