So, I'm starting to tear into the beast. It was making a noise. Took the head to the rebuilder (we figured that was still good) whose gonna use his own block. Taking off the accessories in the front getting prepared to yank the block out... and saywhat? why's the dampener wobbling on the crank just by hand? Not just the outer pulley, but the whole thing. With a long prybar and not much force I was able to shimmy it back and forth, pulling it off the crank all together.

I don't see any metal powder or other damage on the crank. Looking at the dampener it appears the rubber started separating but it isn't all the way gone. Is it possible because of the pending separation it vibrated itself off the crank? What gives? I remember having a heck of a time getting it on initially, no way it was this loose going in. My water pump belt probably had way too much tension on it, or maybe it was due to age, I'm not too worried about why the separation started happening I'm just darn curious how things wore to the point where it was loose to the point where wobble was able to pull it. The key was there and looked ok... I thought it had sheared off at first but no it appears sound after its removed. I'm stumped!

Mine goes on and comes off smooth is it possible the key was bent and that caused you problems getting it on.

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85 d-100 HEI 2BBl
06 Toyota Corrola

Key looks fine, the part sticking out the timing cover. Yes it is supposed to go on and off smooth, but with a tool, not hand pressure. Only reason for the prybar was just for the reach. I could wobble it back and forth by hand just after I took the belt off before I ever touched it with the bar. There is 100+k miles on this rig since I installed it.

I pulled the timing cover just now. The crank snout does appear to have some battle scars. I'm able to slide the dampener to within 3/16"-1/4" of the crank gear by hand without any tools. The key looks fine to me. The last 3/16"-1/4" has an oil stained color to it and doesn't have any "scars", just what appears to be original machine marks, individual circles going all the way around the snout. The rest of the snout (where the scars are) have a shiny unstained chrome like appearance.

Is the dampener supposed to be touching the crank gear when its on fully (sandwiching the oil slinger between the dampener and gear)? I wonder if years ago it never got fully pressed on. that 1/4" band of unscared oil colored crank makes me think the pulley wasn't all the way on.

Yes, you are supposed to press the damper on until it contacts the crank sprocket and stops. You can definitely feel when it contacts the sprocket, it's like running into a brick wall.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Here's a photo of the band I was talking about. I can slide the pulley up by hand to that point and it stops. Looking at the sealing surface of the damper it appears that the rubber seal was riding on two different spots, and they are apart about the width of that oil stained band.

I believe I found my issue. Dampers are not flush on their outside surface but I thought that they were. The center section is set back 1/16", give or take. I bolted a serpentine pulley to the face of the damper that's the same outer diameter. It had a flat back surface. Once the bolts were tightened this pushed the outer pulley groove part of the damper back, distorting the rubber bonding stuff. I guess it just vibrated itself to death. It seems the crank material isn't as hard as the damper material so the crank got damaged.

I'm curious though, dampers slip and fall apart but don't do this sort of damage ... why now? If the bolted on pulley wasn't centered perfectly, would it matter? Not a huge amount, but 1/16" off? Wouldn't think so, the stock bolt on ones are just centered by the bolts.

On that note, this time around I've made a spacer to go between the pulley and damper that only touches the center part. The outer edge is round, however the center hole is not perfectly centered. The bolt holes are also off relative to the center and also had to oversize all of them so the bolts go through. Should I be worrying about this throwing off the balance? Kind of paranoid now with this whole crank snout damage issue.

I wonder if your damper is split (cracked) down its keyway. You may not see it with the damper off and no pressure pushing the crack open.

Lou

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Home of Slant6-powered fun machines since 1988

I didn't see any cracks and the damper fits snug on a different crank. This crank's done unless its welded up.

Any thoughts on how sensitive the weight distribution is of the spacer and serpentine pulley?

Interesting.

I am betting the additions will not affect balance, as long as those individual parts are balanaced decently.

Lou

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Home of Slant6-powered fun machines since 1988