thanks Patdaly for clearing that up. The gasket through Cummins dealer in Tucson was $300 plus shipping. The Felpro was only $80. I had read several posts on here saying how bad Felpro's were but I've always gotten good service from them in other (non-diesel) vehicles I've used them on and I have competing demands for the few bucks I have and it was hard to justify even with my issues. I have plenty of micrometers and calipers to measure with, perhaps for the good of all someone can measure the gauge's and publish what those dimensions are for those of us like me who aren't as well informed.

 

Thought some of you would get a kick out of this. My truck has been back together for a few months and I've put about 4K miles on it since the head gasket replacement detailed in this thread. I had encountered head bolt breakage when reusing my old ones so I bought a new set from cummins. While I'm partial to ARP quality, they only offered studs. So I went with new bolts from cummins instead. They torqued up beautifully and all was good. I left them all at 100 ft. lbs even though I wanted to follow most folks recommendations and final torque to 120 ft.lbs. Rightly or wrongly I wanted to heat cycle the engine some before my final torque. So today I went to retorque them to the final 120 ft. lb. number. Retorqued all to 100 to start and few moved but a tiny bit. Went up to 110 on wrench and had trouble when I got to #8 and #9 (in torque sequence) as they kept turning and not torqueing. So I pulled them out and the picture is attached. I hope the stretch in the bolts is visible in the picture. My faith in cummins quality is gone. Do you guys feel I can just replace the two bad bolts and move on?

 

Holy moly that looks like a 1/4". No way!! Yes I'd lose confidence in whoever sold ya the bolts. I'd be at cummins blowing my gasket for sure!! That is just unreal!! I've had bolts stretch maybe 2 thread max but nothing like that! Good luck with your truck!

 

Thanks for making me feel a little better smoking$$away. The cummins rep suggested I don't know my own strength. Problem is I'm working thru a dealer, Inland Kenworth, in Tucson. I have a feeling that no warranty will apply as I chose the incremental torque method instead of the cummins specified torque plus a quarter turn method. Call me silly, but I think cummins has a bolt supplier problem.

 

Gonna try them studs now?

That's a good bit of stretch. When's the last time the ol torque wench was sent out for certification?

If you used new Cummins bolts why not use the Cummins torque to yeild method instead of just foot pounds?

 

93flatbed- wrench was calibrated by manufacturer less than one year ago. And yes If I have to pull a head off any cummins engine ever again I will use ARP stud kit for peace of mind. In fact I'll be telling customers if you won't buy the ARP stud kit I won't do the work. period. I had a difficult time accepting the usefulness of the torque to yield because 1) it was used when this engine was assembled and it didn't hold up well. 2) The method supposedly requires room temperature but I could not find which room - A 100 deg one like where your at or 30 deg one in Minnesota. 3) experience has taught me that a hot re-torque will usually show that some bolts are looser than others indicating temperature directly effects the bolts. The torque to yield system doesn't lend itself to a re-torque. There was much discussion on here and little definitive agreement on if you tried it do you do one at a time or loosen all and redo. The latter, to me, seem risky in potentially delaminating a well sealed gasket and creating a leak. I still don't feel (not that I know for sure) the method I chose was necessarily wrong for the long term. But I'm certainly questioning cummins quality these days.

 

why are you saying that the as assembled head torque method didnt hold up well? mine made it 20 years and almost 300,000 miles before it started leaking.


I do not follow the argument on temperature variation and why it effects the torque turn method and not the torque only method? I understand that variations in temperature will have an effect on the torque value that you get......but the final turn has nothing to do with temperature??

I would say that the higher the torque value the more variation you will see based on different ambient temperature conditions. so if room temperature is your concern then torque turn will give you closer end results when compared to the same process in a different temperature area.

Torque turn is set to 90 ftlb then additional 90*. well 90* is 90* if the temperature is -50 or 150 its still a quarter turn. now try torquing to 120 ft lbs at -50 and doing another to 120 ft-lbs at 150* and see how close the bolt stretch is on the two bolts? If room temperature is the concern then I dont see how torque turn could be less consistent and think that its probably another reason why the method is used in the first place.

This way dealers from Florida to Alaska can do the procedure with comparable bolt ELONGATION. (stretch is what we really care about anyways)

 

taterfarm - I say didn't hold up well since at 117K when I bought the truck it had already been leaking oil for some time and when I removed the original head bolts some were hardly finger tight and others were quite tight. I'll ad the prior owner kept every receipt since new so well documented that no prior work had been done and no mods that tend to blow out gaskets either. I'm not saying I'm right by any means, just sharing my thoughts. You bring up some valid points that I'll have to think about and research. Thank you.

 

Man there's been a ton of discussion on this with some pretty convincing arguments by experienced professionals and I'm still left scratching my head...

 

Last time I used bolts I went torque to yeild, all went down nice and even. I used a little anti seize on the bolts rather than the engine oil.

Only other thing you may want to do is check the block. Maybe something going on there causing this.

Possibly barrow someone's torque werench too? Take yours on the snapon truck most of them have a simple torque measuring tool affixed to the wall to check your wrench.

 

I would replace all of them, one at a time, and keep the torque at 100 Lb/Ft.

Those bolts are torque to yield, they did exactly what they were supposed to do.

My FSM calls for a torque to 66 Lb/Ft., check again at 66, then the long 12 MM bolts get taken to 89 Lb. Ft, checked again, then a 90 degree turn on all bolts.

I know there are people who report other torque values, but let me ask you, how do you know their torque wrenches were calibrated?

There is nothing wrong with Cummins quality........

 

Man, I thought I had bad luck. Sounds like you are just on the wrong side of the odds. I will say that my plow truck with less than 100,000 has had many bolts fall out, I think it idled a lot with not much care from the previous owners. there was only one bolt in the injection pump when I bought it and I tightened it with my fingers, there where empty holes and loose bolts all over the poor thing. The vibrations on these trucks can do some funny stuff, especially when the pump is just hanging there out of time

Me too, Its tough to find an honest method that is not biased by an endorsement or proprietary product that leans to one method over the other.


Cummins factory bolts are torque plus turnand are not designed to go beyond their yield strength. There are other bolts that are torque to yield and they are supposed to look just like the ones in the photo and are a one time use only. Cummins bolts are not one time use and that's why the head gasket kit has a stretch gauge in it.

The two different torque values for the different length bolts is very important too, glad you put that in here. That is one thing that I have yet to see in a torque only method for any type of head fastener and is one of my concerns with the torque only method, those short bolts will elongate at a different rate than the long bolts.

 

Uhhhh........ If the bolt gets longer, it has exceeded it's elastic limit, or yield strength, whatever you want to call it.

The design is to hit the elastic limit, but not stretch it too much. Theoretically you can do that a couple of times, but not more. Thus the stretch gauge.

If I ever pull my head, I'll go to studs and torque.

 

This is very important!

elastic stretch and beyond yield strength are two VERY DIFFERENT things.

If you pull on metal with a known safe load then it will stretch and when that force is gone it will return to its original length, this can happen many many times in the elastic range and still have very predictable strength and characteristic(that's why its called elastic... it goes back to the same shape). Once you go beyond yield strength then you enter the plastic range and the predictability of future cycles is gone as the strength is quickly reduced to the point of failure(this is when it will visually neck and stretch like the photo).

The design is not to reach this yield point where the bolt stretches beyond return, if it was it would not be a torque plus angle bolt and it would be called a torque to yield bolt.

I believe the reason for the stretch gauge is to know when the bolt has been fatigued and will no longer go back to its original length. If it was a torque to yield bolt then there would be no stretch gauge as all the bolts would be junk if they are removed. these bolts are all torqued beyond the yield point (yield point is very predictable and repeatable and will give an equal holding force for a one time use), you can not reuse a torque to yield bolt as every bolt will look just like the photo the first time they are used.

 

Doh, I knew that and still blew it.......... Glad you pointed it out.

One thing for certain is that at the very minimum his short bolts were over stressed, and we don't know for sure if the long ones were.

I would still replace all of them and follow the Cummins spec. if I didn't go with ARP studs.......