new or used flywheel bolts?

[maverick350]

Sec 6 pg 31 step 6 of engine service manual states to put lock'n seal on bolts if reusing.

Implying acceptable procedure to reuse.

Last time I had one of these off, it was a cracked flex plate on a c6 mated 6.9

New bolts came with the plate, and I compared them with the old ones. The threads were stretched to the point where it looked like a totally different thread pitch.

Curious if anyone has more experience on this, is the stretch normal? or were my old bolts over torqued.

 

[maverick350]

Eh, either way, I'll get new bolts and compare again.

 

[icanfixall]

If... And only if.. A crank bolt was improperly torqued it will stretch the threads. In normal install a crank bolt will not stretch. So reuse is common. I suggest for the most part if you can determine that bolt threads have NOT stretched. Then reuse them. Otherwise be safe and just replace them. That way you will not need to repair an oversite mess when the flywheel comes off because you could not "see" the damaged bolts.

 

[maverick350]

Third flywheel pulled, and all three had stretched bolts.

Seems weird that all three would be stretched, but I suspect an impact gun was the install method.

I ordered arp bolts, and some grade 9's from mcmastercarr.

 

[icanfixall]

Sounds like this truck or engine was repaired by the same gorilla hands "mechanic" when a flywheel was needed. Flywheel bolt torque is 47 lbs and not a good place for the ever so popular idea "if a little is good a lot is better" idea on torque.

 

[maverick350]

Yeah, you might get lucky, but if you flip the bolts and the threads don't lay in nice and pretty over the entire length I wouldn't trust them any more. Took me a while to figure that out, but that's my go-nogo gauge.

and incidentally, the luk single mass bolts were just a hair over 2" and the dual mass bolts are closer to 2 5/8"

 

[maverick350]

finally got my new bolts in, ground them down just a bit to get the right length. Now for locktight.

According to the manual,.. Lock'n seal 577 588 c1.

two places I found reference are

http://www.motofab.com/data/pdf/loctite_oem_product_guide.pdf

This chart cross references 577588c1 to 242 blue threadlocker

http://www.itwpf.com.au/permatex/pdfs/approvals/8.pdf

This chart cross references 577588c1 to permatex aviation foma a gasket no 3 sealant.

Can't imagine using form a gasket, i wonder if they screwed up their chart.

The product description for 242 describes application as sealant as well as its locking function. It doesn't mention anything about compatibility with engine oil. States service temperature to be 300F.
242 it is!

 

[riotwarrior]

Ok....without reading links.....I am blimd...

ANYTIME and I meqm qnytime a bolt torque is provided there needs to be a caveat....dry....with thread locker .....or lube.

A Dry bolt will always yield to torque before one w thread locker or zealant or lube.

This is critical to prevent thread distortion and over toque....

but *** do I know

JM7.3CW

 

[maverick350]

Valid point. I haven't come across anything yet in automotive manuals specifying wet or dry torque. in the case of new oem bolts, the goop is semi dry and I expect the torque yield is different than liquid threadlocker. One might be inclined to add 5% but that's out in the wag land.

 

[maverick350]

Although in this case, 47 ft lbs is the standard torque for a 3/8-16 grade 8 DRY.

http://www.intermotive.net/Tech Tip/Tech Tip - Jan 08.pdf

 

[TahoeTom]

The standard torque in the manual assumes clean threads and motor oil on threads. If a thread sealant or thread locker is called for then obviously no oil. I used Permatex thread sealer, but don't know if that is the best. It comes in a tube and I feel it lubes threads. It is non hardening and not a thread locker.

 

[OLDBULL8]

I argue with myself all the time. Then I procrastinate for fear I'd do it wrong. Then I wonder if the torque wrench is accurate, haven't had it checked in 3 years. Then I put blue thread locker on, torque it up, now I know it's not going to loosen up. Feel better now, where'd I set that beer down.

 

[FORDF250HDXLT]

i ain't skeered

red loctite & 47 ft lbs on original bolts used last fall on log trucks' flexplate.same will be used today on chip trucks' when the flexplate arrives.

 

[OLDBULL8]

http://www.oilburners.net/forums/showthread.php?52369-bolt-torque-specs

 

[FORDF250HDXLT]

http://www.oilburners.net/forums/showthread.php?52369-bolt-torque-specs

says:
Flexplate mounting bolt (automatic transmission)
89 ft. lbs.

i wonder where he got that from?

edit; oh i see.you scared me Bill! i just checked my manual and i see 47 for idi and psd is 89.then i see you linked to the psd section.don't snug 'em up that tight guys! might be what happened to the op's bolts.someone might of mistakenly snugged 'em up to psd spec and stretched 'em.