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Front end noise question

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

Reply to
Mark
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Support bearing on the passenger side axle shaft?

Ken

Reply to
NapalmHeart

Reply to
p_vouers

Definitely appreciate the input. Trans. mounts I can inspect fairly easily.

Do you have any thoughts on how to inspect the support bearing?

-Mark

Reply to
Mark

messagenews: snipped-for-privacy@v45g2000cwv.googlegroups.com...

Reply to
Mark

Visual inspection of seals. Rotate the shaft back and forth watching and listening for anything abnormal.

Ken

Reply to
NapalmHeart

What you say makes sense, but stranger things have happened. This is not something that has been mentioned here very much, but I'm just brainstorming from the information that you provided in your OP.

Maybe Lane will weigh in on this?

Ken

Reply to
NapalmHeart

I'd replace the idler pulley if you believe it is marginal, and then re-do your tests.

I recently had a roaring noise from the front end that would only be present when driving straight ahead. I ended up putting the car on jackstands, putting it in gear, letting it idle, and listening. I repeated this after removing the wheels, then the brake calipers, then an axle (you need a plug to keep the fluid from running out of the trans to do this though, and I'm not sure it's the healthiest thing to do...). By pulling parts out of the equation, it made it very easy to determine what it was. Ended up being a wheel bearing. Didn't take all that much effort to remedy and saved a lot of $$ by doing it myself. BUT, I was also very ready to take it to my local Saturn to have them do a diagnosis if I wasn't able to determine what was at fault myself. Paying their fee is almost always cheaper than guessing and replacing any parts that don't need it.

Good luck!

Lane [ lane (at) evilplastic.com ]

Reply to
Lane

Thanks so much p_vouers, Ken, and Lane. I'll be doing some exploring this weekend again with these items in mind. I'll [post some info on Monday.

Reply to
Mark

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