Harmonic Balancer Rubbing Timing Cover - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70heavyhalf · 07-24-2007, 10:11 PM

I noticed the Harmonic Balancer/pully on my 250 inline 6 was extremely close to the timing cover. Upon removal of the balancer, deep groves were cut in the cover, and one large crack. Any ideas as to why this would happen, except for someone installing it too close to the cover. Or maybe the thrust bearing is worn out and allowing the crank to walk a little.
Thanks

Sport/Truck · 07-24-2007, 10:18 PM

Or the rubber on the damper allowed the outer ring to slip & make contact with the cover.
Got pictures?
s/t

70heavyhalf · 07-24-2007, 11:10 PM

My dad and I took another look and we tried to move the crank from the rear of the engine and we are able to move the crank slightly with our hands so we think the thrust bearing is worn beyond spec.
Here are some pics.

70heavyhalf · 07-24-2007, 11:17 PM

sorry forgot of pics.

70heavyhalf · 07-24-2007, 11:21 PM

Here are a few more pics.

70heavyhalf · 07-25-2007, 11:28 AM

Some one has to have an idea.

jhow66 · 07-25-2007, 12:03 PM

Balancer only installs in one position. Check the balancer to see if the outer ring is on the same plane as the inner. Only two thing will cause this-thrust bearing or balancer.

cooters · 07-25-2007, 12:23 PM

from the pic it looks like the crank is way to far back, check the thrust bearing.

70heavyhalf · 07-25-2007, 02:36 PM

Thanks for all the help, it looks like the thurst bearing is worn because we are able to move the crank with our hands slightly. So the engine is going to need a rebuild so I guess its time to put the 350 in.
thanks again

PanelDeland · 07-25-2007, 09:00 PM

If you can tell the crank is moving by hand then the thrust bearing is worn.Or you may have a bigger problem.

07-24-2007, 10:11 PM	#1
70heavyhalf Registered User Join Date: Jul 2006 Location: CA Posts: 69	Harmonic Balancer Rubbing Timing Cover I noticed the Harmonic Balancer/pully on my 250 inline 6 was extremely close to the timing cover. Upon removal of the balancer, deep groves were cut in the cover, and one large crack. Any ideas as to why this would happen, except for someone installing it too close to the cover. Or maybe the thrust bearing is worn out and allowing the crank to walk a little. Thanks __________________ 70' 1/2 ton 2wd 350/muncie m-20/12-bolt rearend Darin

07-24-2007, 10:18 PM	#2
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Re: Harmonic Balancer Rubbing Timing Cover Or the rubber on the damper allowed the outer ring to slip & make contact with the cover. Got pictures? s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe.

07-24-2007, 11:10 PM	#3
70heavyhalf Registered User Join Date: Jul 2006 Location: CA Posts: 69	Re: Harmonic Balancer Rubbing Timing Cover My dad and I took another look and we tried to move the crank from the rear of the engine and we are able to move the crank slightly with our hands so we think the thrust bearing is worn beyond spec. Here are some pics. __________________ 70' 1/2 ton 2wd 350/muncie m-20/12-bolt rearend Darin

07-24-2007, 11:17 PM	#4
70heavyhalf Registered User Join Date: Jul 2006 Location: CA Posts: 69	Re: Harmonic Balancer Rubbing Timing Cover sorry forgot of pics. Attached Images __________________ 70' 1/2 ton 2wd 350/muncie m-20/12-bolt rearend Darin

07-24-2007, 11:21 PM	#5
70heavyhalf Registered User Join Date: Jul 2006 Location: CA Posts: 69	Re: Harmonic Balancer Rubbing Timing Cover Here are a few more pics. Attached Images __________________ 70' 1/2 ton 2wd 350/muncie m-20/12-bolt rearend Darin

07-25-2007, 11:28 AM	#6
70heavyhalf Registered User Join Date: Jul 2006 Location: CA Posts: 69	Re: Harmonic Balancer Rubbing Timing Cover Some one has to have an idea. __________________ 70' 1/2 ton 2wd 350/muncie m-20/12-bolt rearend Darin

07-25-2007, 12:03 PM	#7
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Re: Harmonic Balancer Rubbing Timing Cover Balancer only installs in one position. Check the balancer to see if the outer ring is on the same plane as the inner. Only two thing will cause this-thrust bearing or balancer. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

07-25-2007, 12:23 PM	#8
cooters Senior Member Join Date: Oct 2006 Location: Edmonton Alberta Posts: 458	Re: Harmonic Balancer Rubbing Timing Cover from the pic it looks like the crank is way to far back, check the thrust bearing.

07-25-2007, 02:36 PM	#9
70heavyhalf Registered User Join Date: Jul 2006 Location: CA Posts: 69	Re: Harmonic Balancer Rubbing Timing Cover Thanks for all the help, it looks like the thurst bearing is worn because we are able to move the crank with our hands slightly. So the engine is going to need a rebuild so I guess its time to put the 350 in. thanks again __________________ 70' 1/2 ton 2wd 350/muncie m-20/12-bolt rearend Darin

07-25-2007, 09:00 PM	#10
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Re: Harmonic Balancer Rubbing Timing Cover If you can tell the crank is moving by hand then the thrust bearing is worn.Or you may have a bigger problem. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"



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