Harmonic Balancer HELP!!!!!
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Freshman User
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Harmonic Balancer HELP!!!!!
Alright so I have a '91 f350 6x4 351w 16x,xxx miles
So i was driving down the road and my truck started shaking like crazy and was making a tearable clanking noise. so i pulled over climbed under the truck to find metal shavings everywere and the (big metal ring) around the pully was totaly lose. so here are my questions:
is this normal to break?
what would have caused this... age?
is the front seal easy to replace once the pully is off?
is anything else that should be done at the same time as this?
thankyou in advance for all of your help.
-Adam
So i was driving down the road and my truck started shaking like crazy and was making a tearable clanking noise. so i pulled over climbed under the truck to find metal shavings everywere and the (big metal ring) around the pully was totaly lose. so here are my questions:
is this normal to break?
what would have caused this... age?
is the front seal easy to replace once the pully is off?
is anything else that should be done at the same time as this?
thankyou in advance for all of your help.
-Adam
Fleet Owner
Joined: Oct 2005
Posts: 20,786
Likes: 1,751
From: Kentucky
I have heard of a few harmonic balancers letting loose on this vintage truck. And yes it is caused by age. It most likely was your noise above 3500 RPM.
I have never replaced a front seal on a 7.5L engine, I cannot answer how easy it is to replace.
I have never replaced a front seal on a 7.5L engine, I cannot answer how easy it is to replace.
Tuned
Joined: Aug 2007
Posts: 287
Likes: 1
Harmonic balancer failed.
"is this normal to break?" YES especially with the miles on your truck
"what would have caused this... age?" YES
"is the front seal easy to replace once the pully is off?" REASONABLY
"is anything else that should be done at the same time as this?"
I would check timing chain cover and surrounding area for damage. Other than that, I would replace the timing chain seal (that the harmonic balancer goes through). Check the tightness of the timing chain cover bolts once the balancer is off. Borrow the harmonic balancer removal and harmonic balancer installer tools (2 different tools) from Auto Zone. The job should be reasonably straight forward - at least it was on my 88 F250.
"is this normal to break?" YES especially with the miles on your truck
"what would have caused this... age?" YES
"is the front seal easy to replace once the pully is off?" REASONABLY
"is anything else that should be done at the same time as this?"
I would check timing chain cover and surrounding area for damage. Other than that, I would replace the timing chain seal (that the harmonic balancer goes through). Check the tightness of the timing chain cover bolts once the balancer is off. Borrow the harmonic balancer removal and harmonic balancer installer tools (2 different tools) from Auto Zone. The job should be reasonably straight forward - at least it was on my 88 F250.
Freshman User
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I had the same problem on my 89 302. the balancer drove me nuts when it started to give out. I thought the u joints were bad, rear was bad, driveshaft was bent. Finally when it snapped and I replaced it some of my sanity did return. Unfortunately the rest is lost forever.
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Freshman User
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hey guys sorry it took me so long to get back with the results. The repair went smoothly and i did replace the timing cover seal. The new balencers info sheet said the main resone for failure was oil leak and bad ignition timing ...i had both 
After replacing the truck never ran so well (I've had it for 4000 miles) even got 1 more mpg.
Once again thankyou so much for all of your help
After replacing the truck never ran so well (I've had it for 4000 miles) even got 1 more mpg. Once again thankyou so much for all of your help
Tuned
Joined: Aug 2007
Posts: 287
Likes: 1
"It's nice when a plan come together" Glad it went well. It's amazing how a new balancer improves the overall ride - it did that in my case too.
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Ford Parts Specialist
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From: Simi Valley, CA
At the factory, a thin rubber insulator is placed between the outer pulley and inner damper, then all three parts are pressed together to form a one piece assembly.
What happens: The rubber shrinks, age cracks...then the outer pulley walks away from the inner damper.
If not caught in time, the pulley can completly separate from the inner damper and end up in the radiator core...not pleasant.
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From: CANADA
The real reason harmonic balancers fail has nothing to do with oil leaks or ignition timing, it has everything to do with age.
At the factory, a thin rubber insulator is placed between the outer pulley and inner damper, then all three parts are pressed together to form a one piece assembly.
What happens: The rubber shrinks, age cracks...then the outer pulley walks away from the inner damper.
At the factory, a thin rubber insulator is placed between the outer pulley and inner damper, then all three parts are pressed together to form a one piece assembly.
What happens: The rubber shrinks, age cracks...then the outer pulley walks away from the inner damper.
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