A couple of days ago I noticed a knocking sound coming from my car at start up and low idle. It's hard to explain but reminds me of a diesel engine (but not nearly as loud). I wouldn't describe it as belt squeal, I've never really had that problem. I first thought it was maybe a bad tensioner or idler pulley. I noticed the drive belt was coming off of the crank pulley by two ribs (slipping away from the engine). I checked everything, and put the belt back on correctly and it immediately slipped back off again at start up. I then took the drive belt completely out and started the car without it on. The sound completely went away. During this whole process I didn't mess with the A/C belt.

Tried troubleshooting and my idler pulley had a slight catch in it and made some noise when I spun it. I bought a new idler, serpentine belt, and tensioner. I installed everything last night and immediately it happened again. The sound came back and the belt slipped off the balancer the exact same way.

I've been reading about all of the crank pulley wobble problems and thought I would check it. Everything appears to be tight, and I didn't notice any "major" wobble from it. Is there a way I can make sure the balancer needs replaced before I go through all of that work? Any other suggestions on what can be causing this is greatly appreciated.

Lastly if I do have to replace the harmonic balancer who makes an aftermarket pulley the same diameter as stock? I noticed summit has an underdrive pulley for $160.00 and would probally go that route to save some money. Does anyone know which crank pinning kit to get that will work with the Summit balancer?

Thanks!

 

Your stock balancer has failed. The rubber inner layer has seperated and allowed the inertial ring (the part the belt rides in) to move. Fix this immediately as it can cause significant damage to the front engine cover, oil pan and oil pump. Ask me how I know .

Do not use a stock balancer, purchase an aftermarket balancer from either ASP or Powerbond. Both make a balancer in the stock diameter. If you are not running a super charger it is not needed to key the crank but not a bad idea either just not absolutely needed. The OEM balancer is a piece of crap - spend a little money and get the correct piece.

 

Hi Xtream

First off you need to fill out your profile so people can tell what year and type of car you have. That helps people try to figure out your problems based on year and miles.

Sounds like your balancer is coming apart or walking off the end of the crank. Since you already changed out the other parts yourself, I presume you will change out the dampner? If you do, you need to get a good puller and get an ARP replacement bolt to make the installation easier.

Pinning the dampner is not necessary unless your going to be seeing lots of HP with a supercharger or ?. The most important thing is to make sure both surfaces are clean and free of burrs. DO NOT put lubricant on the taper as they are designed to go together dry.

I am sure you'll have other questions about removing the rack and radiator so keep us informed.

Mike V

 

Here you go:

http://forums.corvetteforum.com/show....php?t=1913491