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shredding snake belt

jmaxj

NAXJA Forum User
Location
in My shorts.
i keep shredding my serpantine belt on my 91 xj with the 4.0ho and can't figure it out there is nothing that i can see that it's hitting on so any help would be appreciated


thanks
 
Chances are your harmonic dampener is failing and has moved out of alignment in relation to the serpentine belt. The dampener is attached to the crank stub and is a two piece affair that contains a concentric vibration dampener pressed between the inner wheel and outer pulley ring. When the rubber gives out, the outer ring of the dampener begins to creep against the edge of the serpentine belt.

Erik
88 Comanche
 
Erik the Red said:
Chances are your harmonic dampener is failing and has moved out of alignment in relation to the serpentine belt. The dampener is attached to the crank stub and is a two piece affair that contains a concentric vibration dampener pressed between the inner wheel and outer pulley ring. When the rubber gives out, the outer ring of the dampener begins to creep against the edge of the serpentine belt.

Erik
88 Comanche

I should have added that if your dampener is the culprit, it'll need to be replaced.

Erik
 
Erik the Red said:
I should have added that if your dampener is the culprit, it'll need to be replaced.

Erik

well there is a piece of rubber sticking out of it(the dampener)would that cause it? if so how hard is that to replace?
 
JmaxJ,
The dampener is removed by first removing the dampener bolt and then using a puller to tug the dampener off the crank stub. To give yourself enough room you'll need to remove the radiator (some guys are able to do it without removing the rad but the clearance is so tight that one wrong move and you can bury a wrench in it). Once you pull the dampener off the crank stub, it's simply a matter of pressing the new dampener onto the stub by tightening the dampener bolt down. Since the dampener rotates against the front main seal, you need to be careful that you don't damage the seal when you replace the dampener onto the crank. If your front main seal is leaking, then this would be the perfect time to replace it as well.

Hope this helps.

Erik
88 Comanche
 
yeah its about five steps closer than what i was thanks but one more question, how much do they usually run and if the rubber in a used one is good would that be ok?
 
jmaxj said:
well there is a piece of rubber sticking out of it(the dampener)would that cause it?

Once again, I got ahead of myself. Yes, one symptom of a failing dampener is the rubber swelling out from between the hub and the outer ring. The outer ring is likely either creeping in toward the timing chain cover or moving out toward the radiator. At its worst, the outer ring can grind into the cover or fly off and ricochet into your radiator. One way of checking to see if your dampener is creeping is to take a 6 inch ruler or other straightedge and lay it against the face of the dampener. If the face of the outer ring isn't flush with the face of the inner hub then the pup is a goner and its time to get dirty.

Erik
 
jmaxj said:
yeah its about five steps closer than what i was thanks but one more question, how much do they usually run and if the rubber in a used one is good would that be ok?

A dampener for my '88 was around $65. Not sure about the price for yours. No, nothing on the dampener is reusable--you replace the whole unit.

Erik
 
Get a new one not a used one otherwise the problem will soon come back. Also you need a harmonic balancer for pre 99s I believe since they changed the design thereafter and it wont fit on yours. An aftermarket one is usually available. On the install be careful not to damage the crank treads when drawing down the balancer on to the crankshaft. To reinstall the harmonic use a stud and nut in the end the crank to draw down the balancer on to the crank. To reduce tension while doing so hit on the inner ring a few taps w. a hammer after every couple of turns of the wrench. The next turn of the wrench will then be easier. Using this method is similar to the method in the factory manual and helps avoid stripping threads (when using the bolt instead of stud method or due to excess tension) inside the crank. Remember to line up the woodruff key slot on the balancer with the woodruff key on the crankshaft (it may only bevisible just inside the t-case opening for the crank end). Good Luck. Greg
 
Greg Smith said:
Get a new one not a used one otherwise the problem will soon come back. Also you need a harmonic balancer for pre 99s I believe since they changed the design thereafter and it wont fit on yours. An aftermarket one is usually available. On the install be careful not to damage the crank treads when drawing down the balancer on to the crankshaft. To reinstall the harmonic use a stud and nut in the end the crank to draw down the balancer on to the crank. To reduce tension while doing so hit on the inner ring a few taps w. a hammer after every couple of turns of the wrench. The next turn of the wrench will then be easier. Using this method is similar to the method in the factory manual and helps avoid stripping threads (when using the bolt instead of stud method or due to excess tension) inside the crank. Remember to line up the woodruff key slot on the balancer with the woodruff key on the crankshaft (it may only bevisible just inside the t-case opening for the crank end). Good Luck. Greg

k i'm gonna go buy the parts tommorrow and just making sure i'm right here i need a harmonic dampener and balancer right. and thanks for all your guys's help. -derek

Oh and a new belt.
 
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