Bolt torque with lube

[greencom]

Hi,
I need some opinions, maybe I'm overthinking this. I know a lot of members here use sealant on head bolts that go through water jackets, what concerns me is that this practice lubricates the thread and has a significant effect on the torque that should be applied to the bolt, if the specified torque is used the bolts will be over-torqued, right? I've worked on machinery that used bolt stretch instead of torque values, we had a torque vs stretch chart made up as a guide and discovered that a lubed bolt stretched to spec with a lot less torque applied to it so I know it does make a difference. Does anybody reduce torque with lube? There are charts that show as much as 40% less torque required depending on the lubricant.
Thanks for listening.
Bob R

[w30bob]

Hi Bob,

VPW recommends head bolts have sealant applied and be torqued to 65-70 foot-pounds and stud
nuts to 52-57 foot-pounds. I don't know if folks actually do that or not, but those values are for lubricated fasteners.

regards,
bob

[greencom]

W30bob,
Thanks for the reply. 65 to 70 ft/lbs is what's specified in the TM , no sealant mentioned that I'm aware of, so I guess I'll hold off reassembly for a while.

Bob R

[T. Highway]

Sealant is needed on the head bolts or you will have leaks. I applied sealant to mine and torqued to the TM spec with zero issues.

Make sure that your bolts are in good shape and not pitted or just buy new ones and complete the install.

Bert

[j mccormick]

On most of the vehicles that specify a certain torque reading, the instructions I've read were that that torque was with clean threads lubricated with oil.

Joe

[greencom]

Thanks all,
You guys have the experience, good enough for me. I tend to dwell on details but I figure it's better to overthink than to underthink stuff.
Bob R