head bolts

[doncannon]

Hello all,
has anyone ever pulled out a couple of head bolts? I pulled the 4 outside the valve cover and just wondered if I could just start in the center and put them all back in? and what to use on the threads? Do you think they will be alright?
thank you everyone,
Don

[JeepSJ]

First, you cannot re-use the head bolts. They are a torque-to-yield design and can only be torqued once.

If it were me, I'd pull the head and replace the gasket and put in all new bolts. These engines are already sensitive enough to head gasket problems - I would not take the chance.

If you are going to just put them back in, then at least get new bolts. Use teflon based thread sealer on them.

[doncannon]

what would be the worst it could do without buying the bolts? I have put them in and torque to 20 then 50 then 1/8 turn (book says 1/4 turn)
thank you again,
Don

[NH2112]

Used bolts won't torque to the required spec. What you're doing is torquing the bolts till they stretch past their yield point, i.e. past the point of elasticity. It's similar to stretching a spring too far so that it won't return to its original length. You "may" be able to just use 4 new bolts and torque them to spec, but if it was me I'd do as JeepSJ said and replace the head gasket and all the bolts, for the same reason he gave. There's a lot of load spread out over fewer bolts than there should be - most diesels have 6 bolts around each cylinder, the 6.2l and 6.5l "sorta" have 5, and none are really between the cylinders. So, taking the load off the entire bottom portion of the head most likely changed things at the upper portion as well.

[arveetek]

Okay, curiousity has the best of me...

Do you mind if I ask why you removed those bolts anyway?

Casey

[arveetek]

Oh wait...let me guess...you removed the bolts for extra clearance when installing the new injectors?

Casey

[JeepSJ]

Your bolts are now stretched to the point where they will not stretch again, so they will not provide the proper clamping force. If you go 1/8 turn, you will be below spec and will probably lose a head gasket in a very short time. Re-using head bolts will lead to head gasket problems - it isn't a matter of "if", it is a matter of "when". At a minimum, at least use new bolts and torque them to the proper spec. Bolts are cheap - there is no reason NOT to replace the 4 that you are working with.

[doncannon]

Hello all,
Sorry to question everyone. The diesel book did not say to replace them...just the 82-83 bolts. So where can I get them on a saturday?
thank you all again,
Don

[doncannon]

Hello all,
I got headbolts on Sat. am put them in sat. pm then all that was left was for a test drive. Ohhh baby what a ride!!! I had so much fun (I still think I will be looking for more power). I will just enjoy the truck for now before winter comes....it sure is fun! ooops I said that. I just can't wipe this grinnnn off of my face.
Thank you all,
Don

[john8662]

Awesome!

It's always fun to do a lil tire smokin'

[Ratau]

Ok what about the 81 block? What I understand is that the very first ones did not had TTY bolts, could one reuse them?

If bolts was available in South Africa fine I will buy TTY but to import them cost a lot. I would rather go for studs if I have to do the job again and pull the motor.

Are studs reusable?

[john8662]

IMHO I'd stay far away from Studs. They do not work well in these engines. The problem with the studs in going to be keeping them from leaking!!

The 82 model bolts were supposedly re-usable, although I have not seen any supporting documentation for this.

[JeepSJ]

Studs are fine, and yes you can reuse them. The key is to follow the instructions and use a teflon based thread sealer where they thread into the block. ARP makes a set for the 6.2/6.5.

[arveetek]

I re-used the original head bolts in my '82 engine when I first overhauled it in 1996. I would have replaced them, but I didn't know any better (that was before discovering TDP). The engine held together just fine for over 120K miles, no head gasket leaks or anything, until I took it apart this spring for other reasons.

Casey