Crank Shake and Odd Wear

[Crawdaddy]

On my Suburban, my main crank pulley seems to wobble a little bit. It's causing the tensioner pulley to jump a bit, and it's also causing very odd wear on an idler pulley (the one between my AC and crank). The wear it visible and shiny spots on the pulley, and when you actually touch the pulle, you can noticably feel the flat spots. I'm guessing that my harmonic balancer is/has gone out, but I wanted a few extra opinions before I break out the major tools and take my radiator and crud out for nothing. Also, if you think this is the case, could someone write a quick procedure on the easiest way to replace it? Thanks a ton guys!

[Crawdaddy]

This morning I went out to the truck, cranked it up, and got under the front of the truck. When I looked at the crank to see if it was wobbling, I noticed that the harmonic balancer was wobbling by the same amount and in unison with the pulley. I'm starting to get worried that the front bearing is wore out and allowing this to happen. I don't want to rebuild the motor, but at the same time I don't want to lose the crank...Any ideas as to what I should do to stop the wobble

[GaryL]

It sounds like the harmonic balancer is trying to separate. If so, I would change it as soon as possible, you don't want that thing to come apart while it is running and send parts and pieces through the radiator, hood, trans cooler lines, etc.

[Crawdaddy]

that's very comforting to know. I was so afraid I was going to have a rebuild up my alley pretty soon. I'm still not looking forward to taking my front end apart to remove and install a new harmonic balancer, but it's better than yanking the whole blasted motor and rebuilding it. I'm assuming I will have to take the radiator out and then use a jaw-type puller to get the harmonic balancer off, and then somehow get the new one on. I have no clue what would be the easiest and best way to get this done. There's nothing mentioning this in my Haynes book :(

[GaryL]

You should use a harmonic balancer puller to remove it, not a jaw type puller. They are less than $20 at the parts store. When you put the new one on, you can tap it on (lightly) a little ways and then when you can get the bolt in 5-6 thread use the bolt to pull it on the rest of the way. Not sure if you have to pull the radiator or not, but would make it easier.

[Crawdaddy]

3 months later... update time. This weekend I finally tackled the harmonic balancer replacement. Everything went pretty smooth. I also replaced the tensioner and the idler pulley. Well, the new tensioner is jumping all over the place, I'd say 1-1.5 inches of deflection. The balancer/pulley assembly also seems to still be shaking a bit, but I don't remember how bad it was shaking before to make an accurate comparisin. However, on a relative's silverado with the chevy 350 in it, her crank/balancer seems to be shaking in the same manner as mine. So now I'm REALLY confused, is what I'm seeing possibly normal and I'm just not used to it?

[PepboysASETech]

I see alot or minor wobbling on many different makes and models of cars. Some is allowable and even the deflection of the tensioner excessively is normal in some cases. For instance if you are having a rough idle caused by misfire or mabe on of your other pulleys are warped or bent alittle. Commonly the p/s pulleys can be bent or not aligned properly causing the belt to get taught and loose causing excessive tensioner movement. I have a hard time believing that the front main bearing is going out. You will head a rapping noise at all engine speeds and also will cause the front main oil seal to go out very quickly. Check for leaks around your timing cover and behind your balencer to locate any leaking. Also alittle trick that i try ALL the time is just simply take the belts off the truck and start it. If the balencer still wobbles alittle that probably normal. Also there are tension spec for tensioners, dont know what they are, lol. But its possible to have a weak brand new tensioner. I work for pepboys and i see bad brand new parts alllll the time, lol. Batteries, alternators, starters, even spark plugs. Keep us posted.