740GL: problems with harmonic balancer replacement

It is an 89 model 740 GL, stock 4-cyl engine, 230K miles on original engine. The harmonic balancer (or crankshaft pulley) that drives all of the
accessories failed. The outer part separated from the inner part. The outer part was turned at an angle of more or less 30 degrees by one of the belts, and it and the belts "jammed" up while the engine continued running for a while, the inner part of the balancer still locked on to the shaft, still spinning. Nothing was left of the rubber, and part of the bottom of the timing belt housing was ground away. Fortunately my wife noticed the overheat and stopped the car before the engine was burned up. Trying to save some bucks (money very tight) I went and bought a used harmonic balancer and installed it. However, it had quite a bit of wobble when I test-ran it, the wobble of a pulley running on a bent shaft. This of course makes the belts vibrate/jump. They are not jumping around so badly that you hear anything abnormal or feel any abnormal vibration when driving....but it looks bad, for sure. Well, I concluded that either I got a bad part, or the shaft end was bent by the extreme sideways pull that must have occurred when the outer part of the balancer got wedged/jammed up. So I spent $120 for a brand new pulley/balancer and installed it. Very bad news....the new one has *exactly* the same wobble as the old one did. Well, the car is actually my brothers', and when he got back in town and needed to drive it for a while, he took it to some mechanic who tells him that the balancer is not put on right and that is why it is wobbling....and says don't drive it at all, it is going to fail and ruin the engine. (We've probably put at least 2000 miles on it with it wobbling!) Now I would hope that he is right---I didn't install it right....but then again, someone who doesn't really KNOW that it is not installed right would certainly look at that wobbling harmonic balancer and conclude it is not put on right. But I cannot think of any way I could have put it on that would make it wobble. I mean, it was hard to get it started on the shaft because the tolerances are *very* close, and it is pushed ALL the way on to the shaft. I could not see or feel any erosion or damage to the shaft at all. The key has it securely locked in place, it's not coming loose. What could I have done wrong? And two different balancers have the same wobble? Its not a "run-out" wobble, it is a lateral wobble, as you would have from a slightly bent shaft. If the shaft end coming out of the block (which I guess is the actual end of the crankshaft, through the front seal?) has been bent a little, then there is nothing to do but a major overhaul to replace or true up the crank, right? If I take the balancer and belts back off, and somehow affix something like a metal ruler to the front of the engine so that it is almost touching the shaft--- then turn over the engine, would this be a good way to confirm a bent shaft? (don't know how practical this would be, as it might shake a lot). I'm getting the car back for some months or maybe permanently....just don't know if we should not drive it at all as that mechanic said....but there is no money for a crankshaft repair, and won't be for a LONG while, and we need to drive is on rare occasions for short distances, as a back-up car. I don't know of any mechanic I can take it to for diagnosis that I can trust....would like the opinion of someone like a pro who knows these engines. Thanks!
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wrote:

[..]
I've only ever needed to take the crankshaft pulley off when I've changed the timing belt. Every time it was an easy sliding fit onto the shaft. It fits snugly against a shoulder and is held firmly in place by a big bolt.
In my opinion, it would take and large force to bend the end of the crankshaft a visible amount, and I wouldn't have expected the tension from the drive belts to have been able to do this. If this has happened, then it may have rung the crankshaft, meaning the whole shaft will be a little out of true. But I guess the only way to be certain is to take the pulley off, and turn the engine over with a dial test indicator[1] set up against the nose of the shaft.
I guess it would be worth running the engine for a minute with the pulley off, to see if it is visible by eye. But make sure the shaft and shoulder is clean and burr free, ditto the inside of the pulley, and make sure the securing bolt is not bent or damaged.
[1] A DTI is a sensitve dial guage which has a little plunger that responds to movement. The gauge is held securely on a mounting bracket, and the plunger rests against the thing to be tested, in this case the shaft. As you rotate the shaft, the gauge will show if it is out of true. A good DTI is quite expensive, but a good engineering workshop may be able to help you for not much money.
--

Stewart Hargrave


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It sounds like you did not install the balancer correctly there is a notch on the crankshaft that lines up with the notch that is removed from the balancer been working on Volvos for 20 years never have I seen a crankshaft bend on a red motor Glenn
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Nodular iron crankshafts don't bend. If you apply enough force to bend it they will snap off. The crank wheel for the timing belt is keyed to the shaft. On the front side of the wheel there is a vertical key (nub) that engages a radial slot in the back side of the damper pulley in addition to the outer belt guard washer (all three pieces must be aligned correctly). If the damper has been incorrectly installed it's likely that the nub has been deformed and you'll have to remove it from the crankshaft and dress it with a file, or replace it if the incorrect installation has split it, in order to allow the pieces to mate up correctly and run true.
Bob
Bob
--
The goal when driving is to miss the maximum number of objects.

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the
outer
belts,
wobble
of
bent
of
*exactly*
while,
I experienced the wobbling once when I got distracted and put the crank pully on 180 degrees off from the way it should have been so the key wasn't sitting in the slot properly. If this is all lined up correctly you may have bent the crank, in that case if you can't live with the wobble I would consider dropping in a junkyard engine if the rest of the car is ok.
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As others have said, very unlikely the crankshaft is bent. In addition, don't sweat the mileage you have put on the engine - that area is mighty tough, a lot tougher than the belts are.
When you remove the balancer, check the end of the crankshaft and the inside of the balancer, where they fit, for debris. If you see galled marks on either from this misadventure, feel them to ensure they aren't sticking out significantly. Fit them together carefully as the others have described (maybe with a new key - they are cheap and easily deformed).
Harmonic balancer failures are very common. When ours failed my wife was driving and noticed the outer part rolling into the gutter behind her! For that reason, I suggest being leery of the used part. The new one should last another 10-15 years. And don't lose sleep over the crankshaft.
Mike

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Well, that is a relief that the shaft is very unlikely to be bent. When installing the balancer, I saw the square notch in the end of the shaft, and corresponding square notch on the inside radius of the balancer, so it was obvious I needed a square key....but that part was gone, had fallen off and been lost. I could only find a piece of steel barstock that was slightly oversize, and so I just filed it down (didn't take much) until I could tap it securely into the shaft slot. So--of course the balancer and shaft are aligned properly, the barstock key insures that they only go back together aligned. But I don't know what this "outer belt guard washer" is. I don't recall any washer like that, although there may have been a normal type of washer on the bolt....but nothing of a large diameter that could be called a "belt guard". Is it missing some critical piece? Thanks all!

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I'm not quit sure, but I think you have made a mistake. As I remember the notch in the shaft is not for the balancer but for the belt pulley, infact the belt pulley would have a protruding tip on the opposite side of the notch on the shaft, this tip should match with the notch in the balancer.
Regards Per Hauge

and
and
don't
a
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Oops - it also occurs to me that the crank bolt washer might be "dished." (It's been a few years since I had the pleasure.) If so, be sure the outer edge fits against the balancer and holds it tight. If you are not having to use a puller to get the balancer off, and if it doesn't provide several mm movement of drag while putting it on and pulling it off, it isn't seating right.
Mike

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core.
in
keys
Or you could go to a junkyard and pull one from another B230, and in the process you'd be able to refresh yourself on how it all goes back together.
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core.
I probably wasn't so accurate in my description, that is I was referring to the timing belt pulley which is not a part of the harmonic balancer with accessory pulleys. The timing belt pulley has the tip that should correspond with the notch in the balancer core. If the balancer is put on 180 degrees wrongly it will be tilted because of the protruding tip on the timing belt pulley. That is what I suggested had happened in this case.
Per Hauge
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That may be exactly what I did wrong, I had balancer flipped around the wrong way. I don't remember mating a pin on the timing belt pulley up with a hole in the balancer. Will check that possibility out. thanks, Jim

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says...

You're absolutely correct, sir. The square key that fits the longitudinal slot in the crank shaft end is cast into the t'belt pulley and extends inward toward the rear of the motor about halfway through the bore. This is because the broach wheel used to mill the slot is round and leaves a radiused end to the slot. The slot forward of the t/belt pulley is otherwise unused.
The nub that locates and holds the damper pulley in place is on the radial axis exactly parallel to the crank slot, as your referenced pictures show. The nub in reference is being replaced in the brickboard article. The author seems to be very lucky. I the cases that I have seen over the years where the crank bolt has been left loose, or the pulley installed out of proper alignment and then tightened to spec. the t/belt pulley cracks along side of the "key."
The belt guard is behind, or should be behind the lower timing belt cover. There is a rounded notch punched on the inner diameter that fits over the nub. If the timing cover were off you would see a narrow square notch that indicates TDC when aligned with the timing mark on the engine front cover (metal piece) behind the lower timing belt cover (plastic piece).
The counter hold tool can be easily modified to lock the Scan-tech damper and will still work to hold the Volvo damper. Probably a better solution than modifying every Scan-tech damper that comes along.
Bob
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At this link you will find some good pictures of the timing belt pulley and also get an idea of what should match the balancer pulley
http://www.brickboard.com/FAQ/700-900/EngineMechanical.htm#FailureofLowerTim ingSprocket
Regards
Per Hauge

and
and
don't
a
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