bad harmonic balancer or bad rod bearing?

JT15601

Registered User
So my 89 sc started making a slight knocking noise and it sounds like a rod knock from a bearing starting to go but the sound seems like its coming from the crank pulley not inside the case itself. I had it on a rack running and looking underneath it and it looks like the crank pulley has about 2mm of wobble in it and you can see the serpentine belt walk from side to side on the water pump as its running. If it were any other vehicle Id say its a bent crank or bad rod bearing but I always hear that these cars have problems with harmonic balancers and before I shell out a million dollars for one I want to be sure. I might be able to post a video but idk how clear it will be. Any comments and tips are greatly appreciated.
 
Have you removed and reinstalled the original balancer? More than once? The stock balancers don't seem to like being R&Red, it seems like there is a high failure rate after they have been reused (crank bolt or center of balancer breaks).

If you got the bux a BHJ is never a bad idea, kinda like expensive chicken soup for a SC ;)

Also I have had a misaligned crank sensor hit the vane on the balancer, but it was more a lighter ticking than a deep rod knock sound, super cheap fix tho, so worth checking

Adam
 
Did you relax the belt and try to move the crank pulley/balancer side/side by hand? Did you check the crank/pulley bolts to confirm they're still there and tight?
 
Well I have never removed the balancer before and I've tried wiggling it but it doesn't move but I've never took the belts off to try n wiggle it. But I've talked the belts off n started it for a few seconds and it still makes noise. I'll check the bolts now and take the belts off n try n wiggle it
 
Sorry to keep posting but I found out one bolt is broke. Should I tighted the other 3 to get by or will that just jack it all up
 
I'd get it off the car so it can be closely inspected - then you can decide if it's still usable. Might be cracked and/or bolt holes are oval'd/egged out, etc. Be sure to use new bolts regardless. Put up a photo here if you can.
 
Well someone before me has definitely messed with it because 2 bolts were 13mm and one was 16mm? And they were all fairly loose (probably 5-10 ft lbs) what are the torque specs for the bolts? I'm going to see if I can get the stud from the broken bolt out now
 
I'd get it off the car so it can be closely inspected - then you can decide if it's still usable. Might be cracked and/or bolt holes are oval'd/egged out, etc. Be sure to use new bolts regardless. Put up a photo here if you can.

What he said. That and if it was my car I'm thinking this thing is spinning 2 to 4K RPM, it's heavy and sitting next to my radiator and AC condenser which neither have any protection from being punched through :eek:
 
Ok so the stud is busted off way up in there. Think if I put locktite on the other 3 if it will hole me off till I get a new HB? I use the car as a daily driver and its not very nice to begin with. I only played $1100 for it. Anyone got the torque specs?
 
From the shop manual for a '95
Crankshaft damper retaining bolt and washer, torque to 140-180N-m (103-132 Lb ft). Pulley bolts 26-38N-m (20-28 Lb ft).
 
Ok I did 25 lb ft with permatex thread locker. It seems fixed. I'll put some miles on it tomorrow to see for sure. Thanks guys!
 
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