Ok, bear with me here. A couple of weeks ago I start hearing a squeak from the front of the engine of my 1999 automatic coupe. Spray a little belt dressing on both belts and it instantly goes away. The next day it's back, only louder. After reading related forum posts, I take it out for a spin even with the noise, and it almost disappears in about 10 minutes of driving, but always comes back when it's cold. So today I take it into a shop for some new belts, pulleys, etc and have them check the crank pulley while they're at it. They say the crank pulley (harmonic balancer) looks fine and it's tight, but when I came in they found that the a/c belt was already off, but not broken. They toss on a new sepentine belt, which lined up perfectly everywhere its supposed to. The a/c belt lines up with every single pulley (tensioner, etc), but it won't line up with the crank pulley as the pulley is too far forward! Huh? They start the car without the a/c belt but with a new sepentine belt, but the nasty noise is still there. Come to find out the crank pulley was actually rubbing against the rack & pinion stuff that's located right in front of it!! But here's the kicker... after about a 15 minute drive again and the car is warmed up, the crank pulley-harmonic balancer-crank shaft (?) actually backs off a bit and stops rubbing! What the heck is going on? They tell me there's no chance that it could be the harmonic balancer because the pulley is on there tight, but with everything I've read here about harmonic balancer problems on the C5's, it makes me wonder. They suspect the crankshaft is loose and it moves forward which makes the pulley rub against the rack, but when the engine warms up (bearings, oil, etc) it somehow sucks the crank back towards the engine and now they recommend changing out the thrust bearing, which they say keeps the crank from moving forward or back too much, but they won't do it. 1) Does this sound plausible at all? 2) Could it in fact be something to do with the harmonic balancer even though its tight and doesn't appear to be wobbling? 3) If it is the thrust bearing, can it be changed out without tearing down the engine? (they say with some engines it can, with a special tool). I look forward to any comments that will shed some light on this and point me in the right direction as I want to get this fixed! Thanks ahead of time to all you C5 guru's out there!

 

Sounds like the balancer has failed. Even if the bolt is tight, the rubber section between the inner hub and the outer pulley can fail and allow the pulley section to move in or out. If it comes apart it will cause some serious damage. Needs to be changed ASAP.

 

Find a new shop ASAP. You need a new balancer. It will cost a a lot of $$ because of the labor to remove the rack. If you ever thought about doing a cam change, now is the time.

 

I agree....sounds like a defective balancer. Much greater liklihood that is the case and far easier and cheaper to replace. Might as well go with an underdrive version and pick up a few horsepower and a little engine response at the same time....possibly even a camswap while your there.

The other thing you can do to rule out the thrust bearing is remove your oil filter and cut it open. If you see major amounts of gold and copper colored flakes stuck in the pleats its not looking good, but my money in on the balancer being bad.

The oil filter idea is a quick and easy way to tell which direction you need to proceed...

Good luck....keep us posted

Tony

 

^

If your crank was walking your engine would be scrap metal.

 

I agree, you need to find a new shop. The crank could NOT have moved enough forward to make the balance hit the rack. You need someone who knows about the LS1 and the shop you are at does not sound like the place to be.

Reb

 

Wow, I knew you guys would come through! This forum is awesome! I'll be getting a new balancer pronto! One thing though that puzzles me (as an absolute non-mechanic person), and that's what the reason would be for it to backs off after warming up, or is that just plane old coincidence? Thanks so much again to all of you that responded so quickly. You saved me a ton of grief, not to mention a ton of money as well.

 

It may be the affect of heat on the elastomer (e.g., rubber) and the fact that it is spinning.

They had a problem with early C6's where they were coming off and damaging the steering rack and the rack would leak power steering fluid. This in turn would get thrown around by the pulley and take off the paint on the car, so get someone knowledgeable to fix it pronto. You should replace the seal as well when you do this.

 

The real damage could be to the crankshaft eventually due to the damaging harmonics & resonance that the dampner is designed to absorb....and if it is moving around you can bet it has already caused some damage to the crank snout as the dampner is a press-fit.

This is a well known problem w/the LS based motors so they should have suspected it from the start.

Also, the LS motors are internally balanced so they do not have a harmonic balancer....they have a vibration dampner instead.

Good luck!!

 

I agree with everyone above. There's alot of space between the crank pulley and steering rack relative to how much the crank would be able to move. Even if your thrust bearing was gone, it would only move forward about the thickness of a nickel before the counterweights began hitting the main caps. Certainly not enough room for movement to cause this problem.

 

Sounds very odd.

Any chance of pics of the pulley when it's cold, then pics when it's warm? Is there clearly an area on the ps rack that shows the rub?

 

Recommend a POWER BOND under drive damper. There a decent price and bullet proof. I JUST installed one on mine! Fit like a glove! I also pinned the crank while I had it off. Couldn't believe how easy it was (if you have the tool! )

I also installe a ARP reusable damper bolt! That is one STOUT BOLT!

My OEM damper was trashed. The hub had a NASTY groove worn in it from the front cover seal and the seal failed. The entire under side of the car was wet with oil!

Yep,,,if you ever thought about doing a CAM,,,,nows the time. Your 86.487% of the way there.

Bill

 

What I wanna know is, how can they tell its tight if the balancers up against the rack????? You cant get a ratchet on the bolt to try and tighten it!!!!!
Find a shop with LS experience. Even a dealer......