So i just did new head bolts this weekend on my truck. I got grade 12.9 allen head bolts and grade 12.9  washers  off mcmaster carr for 84 bucks. The bolts are made in italy and seem like real good quality. I replaced my stock bolts one at a time front to back torquing the bolts to 120ft lbs each time i changed one. I used arp fastener lube and tried to remove as much oil from the holes under the valve cover that had oil in them. This is where i might have messed up by not getting all the oil out of the holes. So 90 percent of the bolts torqued down just fine but some seemed to have a little slip like they would spin slightly more before clicking . Possibly due to oil on the threads. Now i shouldnt have listened to some of the morons on this forum im on on facebook. Some people were saying to do a hot retorque so i started to and the bolts outside of the head would click almost instantly where some of the bolts under the cover seemed like they would keep spinning if i kept at it i got like a 1/4 turn to a half turn out of some bolts and said this just doesnt feel right. So i quit while i was ahaid i didnt want to yeild the bolts or pull threads. My main question is it possible i gained some life span on my 315k mile head gasket by doing this? I wanted to be pro active and try to tighten things up with stronger bolts in the hope of making my head gasket live a longer life. I will say though these allen bolts seem pretty dam stout, the fact the shank is larger is a pluss and the less threads i would think is also a plus scince more threads outside of a hole just means a smaller shank

  On 6/17/2024 at 7:09 PM, daav544 said:

My main question is it possible i gained some life span on my 315k mile head gasket by doing this? I wanted to be pro active and try to tighten things up with stronger bolts in the hope of making my head gasket live a longer life. I will say though these allen bolts seem pretty dam stout, the fact the shank is larger is a pluss and the less threads i would think is also a plus scince more threads outside of a hole just means a smaller shank

 

I think there are too many variables in what you are trying to accomplish to make an accurate conclusion as to whether or not you will prolong the life of the head gasket.

 

One variable is that two bolts of same thread diameter and hardness, but different shank diameters (as you have noted) could have performance differences.  Those differences could affect the elastic limits of either bolt.  So, while both bolts may provide an equal clamping force, one may be able to maintain its clamping force through a longer clamping stretch distance, which would perform well in a large thermal expansion / contraction range.  There is no way to have that information just by looking at two different bolts.

 

Another variable is that you are using a maximum torque specification with a torque wrench while Cummins is using a "torque to angle" specification to reach a final torque.  These different applications could have different clamping force results.

 

A third variable is that one has no way of knowing the rate of deterioration or the actual condition of the head gasket material at any given point in time during the engine's operational life.  Additional clamping force may offer no help.

 

I have the same concern as you regarding the life of my head gasket (I'm at 389,000 miles), but I have decided to run as is until I see the symptoms of a head gasket failure.  It may not be the best decision, just my decision.

 

Of course, I would also like to mention that I certainly have no expertise in this subject - only my experiences.  So, when my head gasket fails and yours doesn't because you performed some pro-active measures, be sure to let me know!

 

- John

So the whole reason i did this is because of this video 

Power driven diesels guy tony did this years ago before they started making their own kits. He put these bolts in on a truck with 300k + miles and ran 50 pounds of boost or more making some good power and did it for years on that head gasket apparently. So i figured if it worked for him why not try it.  If it helps it live to 400k or more on my 150hp injectors id be happy.

The only thing that im not to happy about with myself is not getting all the oil out of the holes. A few bolts felt like they turned more than others while torquing, not by much but i could tell compared to the holes outside the valve cover. Andd the fact i listened to some people about doing a hot re torque when i did that the bolts inside the valve cover that possibly had oil on them felt like they would keep turning if i kept going i got like a 1/4 to half turn out of some before i said this doesnt feel right and stopped before i went and ****** something up like pulling threads or breaking a bolt. I turned the wrench down to like 115 at this time got them to click rather easily then went to 118 and clicked without much rotation but the initial 120 was a butthole puckering moment for sure  lol

Thanks for posting the video - it definitely sheds a better light on your project.   The fellow with the beard seems to know a lot about fasteners.  What I have learned about fasteners over the years aligns exactly with what he is saying.  Good information.  I can see why you are pursuing this.

 

Back to your project - if enough oil was left in a bolt hole, a hydraulic lock could occur when the fastener is nearing the bottom of the bore.   Since oil is virtually non-compressible, the oil would be forced around the threads (spiral leakage).  That could be why the fastener wants to keep turning as you near maximum torque. 

 

Did you have any issue with the washer size in your application?  Just curious, as I may consider doing what you are doing.

 

Also, are you running stock power?  If not, what power level?

 

- John

 

 

 

 

these are the two exact ones i bought and the washer is almost exactly the same size as the underside of the stock bolts. I was happy with the size difference on the shank of the new bolts and the fact they used less un needed threads. Washers are grade 12.9  as well. But back to the oil in the hole thing, on initial torque i got them all to 120ft lbs. But on the hot re torque which i shouldnt have done and just left well alone some of the bolts like i said felt like they would keep spinning if i kept at then i dropped the torque wrench back down to like 115 and got them to click after like a 1/4 turn or so. I should be fine in theory but just worried myself a bit

And as far as power im stock turbo, with intake, intake horn, 7x.010 (150hp) injectors, stock downpipe to a 5in side pipe befoee rear wheels and quadzilla adrenaline but i usually run stock tune/ a 1badvp eco tune that someone was nice enough to send me pics of the settings of that he got for his truck with similar mods.

Now I see why you are concerned about the high mileage original head gasket.

 

When I return from a camping trip (leaving tomorrow) in about a week, I may post your question on the TDR (Turbo Diesel Register) and see what kind of response I get.

 

I have settled for RV275 hp injectors and a mild tune on a Smarty S03. 

 

- John

Id really like to do some kind of test with the stock bolts vs the allen head bolts wish i had a way of measuring a stretch test of some sort. Ill have to take a dial caliper and see exactly how much larger the allen bolts are. From what ive read theres a bunch of people with good results running these kind of bolts, some people 50-60psi on stock high mileage head gaskets for years, some even made 800hp on them and even read about one guy with a pull truck running a marine headgasket with these kinds of bolts and has pushed 100psi. Theres a good video by banks talking headbolts, ill let you hear what he has to say. 

I love gale, truly a godsend like moparman. But have fun camping i just got back from bike week in new Hampshire last week and the week before that we were up there watching the top fuel races