740GL: problems with harmonic balancer replacement

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Jimbo

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!
 
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 [..]
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!
Click to expand...


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


For email, replace 'SpamOnlyToHere' with my name
 
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

--
"*-344-*Never Forgotten"
Is for the New York City Firemen who lost their lives on September 11,2001.
The official count is 343, but there was also a volunteer who lost his life
aiding in the initial rescue efforts. And I will never forget them as long
as I live,
nor should any American.
"Mow Green"
 
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.
Click to expand...

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
 
Jimbo said:
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!)
Click to expand...


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.
 
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
 
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!
 
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
 
Per Hauge said:
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
Click to expand...

In the B230 engine (740/760) the harmonic balancer is integral with the
pulley. In fact, the rubber part that fails fastens the pulleys to the core.
I understand the arrangement in the 240s is different.

I think you have identified the problem, Jimbo. You need a "real" Woodruff
key. They only come in a few popular sizes, and are available in
well-stocked hardware stores. Ace hardware chain stores usually have them in
their plastic drawers of specialty hardware, with roll pins and cotter keys
and things like that. They are cheap enough that you can buy one of every
likely size.

The only washer you need is the thick one that goes under the head of the
crank bolt to hold the harmonic dampener fast.

Mike
 
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
 
I'm not quite 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
timing belt pulley, in fact the timing 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
Click to expand...
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
 
Michael Pardee said:
In the B230 engine (740/760) the harmonic balancer is integral with the
pulley. In fact, the rubber part that fails fastens the pulleys to the core.
I understand the arrangement in the 240s is different.

I think you have identified the problem, Jimbo. You need a "real" Woodruff
key. They only come in a few popular sizes, and are available in
well-stocked hardware stores. Ace hardware chain stores usually have them in
their plastic drawers of specialty hardware, with roll pins and cotter keys
and things like that. They are cheap enough that you can buy one of every
likely size.
Click to expand...

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.
 
Michael Pardee said:
In the B230 engine (740/760) the harmonic balancer is integral with the
pulley. In fact, the rubber part that fails fastens the pulleys to the core.
I understand the arrangement in the 240s is different.
Click to expand...
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
 
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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