Question about valves
Thread Starter
Instructor
Joined: Jul 2002
Posts: 245
Likes: 0
From: Raleigh NC
Question about valves
My engine's developed a nice knocking sound to it coming from the driver's side of the engine, so first thing I did was take off the valve covers to take a gander. I didn't notice anything immediately wrong there but I did notice that all the rockers/springs were even, all fully closed. Is this supposed to be that way? Should there be a time when one half of the engine's valves are all closed? It seems to me that that would indicate that the driver's side is either in compression or ignition all at the same time, and I didn't think it was timed like that.
I cranked the engine and watched the valves and they do all move, and the engine does run, but it knocks really bad and like I said I didn't think one side of the engine's valves were all supposed to be closed at the same time.
I cranked the engine and watched the valves and they do all move, and the engine does run, but it knocks really bad and like I said I didn't think one side of the engine's valves were all supposed to be closed at the same time.
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
It is sometimes hard to tell when engines off what position your valves are at. First I would take a big screwdriver and put your ear to the handle end and listen around the engine while running. Try to iscolate where the noise is coming from. Try listening at the exhaust manifold or headers also with the screwdriver or similar. Knocking can be lots of things like spun bearings or broken lifters etc. Usually number one cylinder is suspect first.
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Can you record the sound and provide a link to the wav file? We need to hear idle, acceleration and deceleration under both unloaded (in neutral) and loaded (in drive/moving), and at constant higher rpm...around 3500 (again both unloaded and loaded).
A knock can be many things...here's some possible references, just off the top of my head:
bearings:
cam - most noticeable under any acceleration and deceleration
crank - increases in volume with rpm
rod - increases in volume with unloaded rpm
camshaft end play: most noticeable under load
piston slap: most noticeable at constant higher rpm...around 3500.
worn lifters: most noticeable at constant higher rpm...around 3500.
bent valve stem: most noticeable at constant higher rpm...around 3500.
It very well could be something else as well...a good audio file will help.
A knock can be many things...here's some possible references, just off the top of my head:
bearings:
cam - most noticeable under any acceleration and deceleration
crank - increases in volume with rpm
rod - increases in volume with unloaded rpm
camshaft end play: most noticeable under load
piston slap: most noticeable at constant higher rpm...around 3500.
worn lifters: most noticeable at constant higher rpm...around 3500.
bent valve stem: most noticeable at constant higher rpm...around 3500.
It very well could be something else as well...a good audio file will help.
