First, I know this is a long post sorry. Thank you for taking the time to read it and give advice.
"95 Saturn SL-2- 80K miles
I have an odd issue. I've been a shade tree mechanic for 20 or more years. Never seen this one and it's really putting a teaser on my brain trying to find it. I have a rapid knocking noise in the passenger side front end that is only present when the vehicle is cold. The sound is very close to a badly loose cv joint with a lot of movement. It is speed dependant and pressure (engine must be pushing) dependant. The knocking can be felt through the floor. Take the car out of gear the sound goes away. In gear the sound returns. Pressure on that side of the suspension makes the sound worse.
The sound goes away all together after a few miles of driving (because the car is warmed up?).
I've done a bunch of testing.
-There are no error codes in the computer.
-Tire has been removed and joints checked by manual turning of axle against parked transmission. No looseness or extra sounds noted.
-Visual inspection of shock showed nothing extraordinary. Manual pushing/pulling against shock showed nothing. Striking shock with sledge hammer showed no unusal sound.
-Rod arm is tight. Dust boot is completely torn, but no wear is evident to account for any noise there.
-Stethoscoped belt driven under hood components. Idler pulled is going bad (noisy bearing) but has no play in it. all else is normal.
-Full on tight turn testing done in both directions without any noise.
Some theories:
-CV Joints? the most obvious, but no classic symptoms (popping in tight turns, clicks in joints under manual test)
-Loose suspension piece? (thorough inspection none found)
-Idler Pulley?- (probably not as sound disappears with transmission disengaged and pulleys should not be able to know when pressure is on engine)
-Motor Mount? - (Sound is speed dependant so probably not)
-Misfire into exhaust? (Should show up on O2 sensor yielding a code in computer)
I'm lost on this one. Anybody have any ideas or thoughts on what I've missed here. Or maybe I've dismissed an idea I should not have?
-Mark