Headstud bottom tap?

cumminspwr11

cumminspwr11

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May 18, 2010
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Do you absolutely have to bottom tap the block on a Cummins? I have done may 6.0s without bottom tapping but this is my first Cummins and I seem to be having HG issues on my build. The block was checked when the new sleeve was installed and I straight edged the head and everything looked good but the coolant system is getting too much pressure under hard runs and is spitting coolant out the resivor- now that I look back tho maybe I just had the system too full?? I only did one hard run down the block after topping off the resivor tank
 
Not familiar with the coolant by pass, can you elaborate? And no retorque yet, I haven't done one of those, I will do that next
 
What psi is ur rad cap rated for and whats the cap poping off at. Could there still be air in the cooling system.
 
I'm not sure of any of the pressures, it's a factory 2003 F-350 6.0 resivor and cap so whatever they are factory, I will have to dig into more next weekend, I did not use the factory temp sensor on the back of the head so I'm thinking it may be possible to pull a coolant pass off there? I'm pretty sure I worked the air out, the heat core is also by past at this current time.
 
Sounds like a blown head gasket. You could try re-torqueing it now, but you might be too late.
 
I always do a retorque on a fresh gasket or a new set of studs. Seems to be a common issue with guys that don't do retorques.


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For full thread engagement, it's recommended to bottom-tap all of the bolt bores.

I agree, sounds like a blown head gasket. If you made a hard run after getting the motor back together and without a retorque, I'd say that's where you went wrong.
 
What are the recommendations on retorquing? The ARP directions say nothing about it and I haven't done it on other motors and haven't had issues.
 
I found the answer to that on their FAQ page.

If you follow the ARP installation instructions, there should be no need to do a re-torque. However, it may be necessary under certain circumstances if the gasket manufacturer’s instructions require it, particularly if a fire ring has been installed. ARP recommends not doing a re-torque on a hot engine.
Click to expand...
 
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I agree with it being a blown head gasket but I want to figure out why, it's the second HG I put in it in under 100 miles, the first one I chalked up to a POS HG but now I'm wondering if I'm missing something, I ran mighty diesel head bolts before the studs-never did any retorques and never had any issues, also like I have said I have done lots of 6.0s without retorques and without issues. That's why I'm thrown for a loop if it really is something as simple as a retorque causing these issues, I didn't fully bottom tap the block but I did chase the threads out.

Thanks for the input guys, I think I'm going to prep my spare head, order a new HG and gather the stuff for a coolant by pass while I'm there- any ideas if the hole in the head for the coolant temp will have enough flow to work properly or should I go the rear freeze plug route?
 
Since the rear expansion plug is the one that could blow out, I went that route with a Keating Machine plate.

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I was just looking at my shiny new 625s. They are not long enough to require bottom tapping. The threads will engage the top of the block before bottoming out. Also, the instructions say you do not need to re-torque. But I still plan on re-torqueing at least a couple of times before pushing it.
 
It seems like the newer MLS gaskets dont require retorques like the older paper type gaskets do. We always get movement on a retorque after a few heat cycles with the 12v gaskets. If you had o-rings it would be even more important.


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I ordered some new valve cover gaskets and I'm gonna do a retorque this weekend and see what happens, nothing to loose at this point.
 
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