Question on harmonic balancer bolt

ah1008

New member
Mar 16, 2024
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Oregon
Bear with me. Have a question. Head gaskets blew at 126k. Have not pushed this truck. Pulled heads, bought kit from Merchant Auto. While heads were being rebuilt, to be safe, replaced water pump. Means removing harmonic balancer. Water pump in, heads back on, torque'd bolt to GM spec, foot pounds plus degrees, pulled flywheel lock. Now I am trying to spin the engine to set rocker arms. Problem is harmonic balancer bolt is still turning, engine is not. Checked to make sure truck was in nuetral, in case, even with batteries out. Question is: am I missing something? Transmission in park,,, more torque on bolt. I watched videos, appears it takes a bodybuilder to torque the older engines? Anyone been where I am before? 2013 LML Duramax
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Mid Michigan
First: Moved to LML section. Please dont use the Intro Section for Tech.

Second: You'll get further if you give particulars in your posts. For instance: How much did you torque the balancer bolt originally? IIRC, it was 285 ft/lbs.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
Sure the water pump is not bound and was put in correctly? Did you leave water in any of the cylinders and the rings have rusted to the cylinder walls? Will the crank move in either direction even a little?
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,145
4,902
113
Phoenix Az
First: Moved to LML section. Please dont use the Intro Section for Tech.

Second: You'll get further if you give particulars in your posts. For instance: How much did you torque the balancer bolt originally? IIRC, it was 285 ft/lbs.

LML is 74ft lbs, then 90*. GM changed it from the older models of 74ft lbs and 105*.
 

Ron Nielson

Active member
Oct 11, 2009
690
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Berryton, KS
Problem is harmonic balancer bolt is still turning, engine is not. ....... Question is: am I missing something?
You may not have been aware that there is a locating pin in the crank that fits into the damper so that the damper is locked into position with the crank. That pin may have slipped off and you didn't notice it.
 

ah1008

New member
Mar 16, 2024
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Oregon
First: Moved to LML section. Please dont use the Intro Section for Tech.

Second: You'll get further if you give particulars in your posts. For instance: How much did you torque the balancer bolt originally? IIRC, it was 285 ft/lbs.
Thank you for that. Will not do that again
 

ah1008

New member
Mar 16, 2024
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1
Oregon
You may not have been aware that there is a locating pin in the crank that fits into the damper so that the damper is locked into position with the crank. That pin may have slipped off and you didn't notice it.
Thank you. I did notice the pin, was surprised considering the balanced is keyed
 

ah1008

New member
Mar 16, 2024
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1
Oregon
Sure the water pump is not bound and was put in correctly? Did you leave water in any of the cylinders and the rings have rusted to the cylinder walls? Will the crank move in either direction even a little?
Good point, while heads were off, I cleaned everything and coated cylinders with oil. I was worried about the same
 

ah1008

New member
Mar 16, 2024
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0
1
Oregon
Im maybe thinking, pull pushrods, put back together. bump engine with starter. Engine spins, throw pushrods in, adjust rockers. If I break the balancer bolt, Im pulling the engine. If the starter wont spin it, Im pulling the engine. Not familiar enough with Duramax to know if I am missing something. Will check the water pump before plan B. Thank you
 

ah1008

New member
Mar 16, 2024
9
0
1
Oregon
Is the balancer fully seated?
I assume so. I installed with pin to keyway. I painted the timing groove for rocker adjustment, groove is closest to block. When I installed the balancer, slid on without a bunch of effort. I did not take a mallet to it. Did not figure that would be good. Distance between edge of flywheel and front cover seems between 1/16 and 1/8.
 

ah1008

New member
Mar 16, 2024
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0
1
Oregon
Sorry for not saying this. Thank you for your responses. I am new to diesel. Good knowledge of gas. This one has me at a loss