Rod knock/bent valves question - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

nisileighty · 04-25-2018, 07:38 PM

I’m not sure if this belongs in the small questions thread, but I’m at a dilemma.

I’m fixing a 2006 Altima QR25 which was ran with low oil and spun a bearing. Upon removing the cylinder head to see if it was salvageable, I did a pressure test to test the valves and it lost pressure/valves were leaking. There was no visible bent valves, but the air was definitely coming through.

Now my question, if a rod bearing is spun or he connecting rod it loose, is it possible that it could bend a valve? At first I thought yes, reason being that there’s now extra room for the rod/piston to move up and down while the crank is still in its normal position, but then I realized that the compression of the air would still be pushing the piston downwards away from the valves.

Feel free to say your opinion! I’m interested to see what’s up with this thing.

04-25-2018, 07:38 PM	#1
nisileighty Zilvia FREAK! Join Date: Feb 2016 Location: Seattle, WA Posts: 1,218 Trader Rating: (4) Feedback Score: 4 reviews	Rod knock/bent valves question I’m not sure if this belongs in the small questions thread, but I’m at a dilemma. I’m fixing a 2006 Altima QR25 which was ran with low oil and spun a bearing. Upon removing the cylinder head to see if it was salvageable, I did a pressure test to test the valves and it lost pressure/valves were leaking. There was no visible bent valves, but the air was definitely coming through. Now my question, if a rod bearing is spun or he connecting rod it loose, is it possible that it could bend a valve? At first I thought yes, reason being that there’s now extra room for the rod/piston to move up and down while the crank is still in its normal position, but then I realized that the compression of the air would still be pushing the piston downwards away from the valves. Feel free to say your opinion! I’m interested to see what’s up with this thing.