2005 Hyundai Sonata with G4JS 2,4 I4 engine developed a dull knock when cold under load. Bad wrist pin is the main suspect. The engine will be torn down during the coming weekend, new pistons, rings, bearings of standard size will be installed if the cylinder tolerances are ok. One connecting rod will also be replaced. But I am still only about 60% sure that this is indeed piston slap/ wrist pin knock.
The engine knocks loudly under load after cold start, especially if oil level is low (the lower the oil level, the louder the knock). The sound is similar to piston slap, i.e. dull, tapping knock, like a piece of wood is hitting metal in the 1,200-2,000 rpm range. Also the colder the weather outside, the louder the knock is.
The noise is somewhat quieter if higher octane gas is used. The engine doesn't knock at idle, however it produces a diesel like clatter when idling at operating temperature. The knock fades away when the engine is hot, but a little bit of it still remains.
Recently did a compression test with the following results: 13.0 - 12.5 - 12.5 - 12.5 kg/cm2 or 180 - 175 -175 -175 psi. Engine spec according to manual is 12.2 kg/cm2 or 170 psi.
The knock doesn't go away immediately after the engine reaches operating temperature, but after driving maybe 20-40 minutes. Even if the engine warmed up until op temp before drving, the engine still produces very audible knock. However, if I warm it up for about 15 minutes (reaching the op temp), and the let it sit for 20-40 minutes, it doesn't knock that loudly when driving.
Please listen to the video of the knocking engine on Youtube:
http://www.youtube.com/watch?v=IlneoC9Yxzw
A mechanic that looked at the car says that it is rod bearing knock or piston slap or wrist pin knock.
IS THIS REALLY WRIST PIN KNOCK / PISTON SLAP?
Can a bad wrist pin cause piston slap (dull knock under load)?
The engine knocks loudly under load after cold start, especially if oil level is low (the lower the oil level, the louder the knock). The sound is similar to piston slap, i.e. dull, tapping knock, like a piece of wood is hitting metal in the 1,200-2,000 rpm range. Also the colder the weather outside, the louder the knock is.
The noise is somewhat quieter if higher octane gas is used. The engine doesn't knock at idle, however it produces a diesel like clatter when idling at operating temperature. The knock fades away when the engine is hot, but a little bit of it still remains.
Recently did a compression test with the following results: 13.0 - 12.5 - 12.5 - 12.5 kg/cm2 or 180 - 175 -175 -175 psi. Engine spec according to manual is 12.2 kg/cm2 or 170 psi.
The knock doesn't go away immediately after the engine reaches operating temperature, but after driving maybe 20-40 minutes. Even if the engine warmed up until op temp before drving, the engine still produces very audible knock. However, if I warm it up for about 15 minutes (reaching the op temp), and the let it sit for 20-40 minutes, it doesn't knock that loudly when driving.
Please listen to the video of the knocking engine on Youtube:
http://www.youtube.com/watch?v=IlneoC9Yxzw
A mechanic that looked at the car says that it is rod bearing knock or piston slap or wrist pin knock.
IS THIS REALLY WRIST PIN KNOCK / PISTON SLAP?
Can a bad wrist pin cause piston slap (dull knock under load)?