its not the 6.0 in my sig. that truck is bone stock still and runs pretty well.

ive been helping a friend with his 6.0l that is having this problem. if i understand correctly the oem head gasket is universal for the alignment dowels ( two of them) which means if he has the smaller of the two sizes (18mm i think) the gasket would have a minimal amount of room to shift and hang the push tubes up enough to not fully seat in the lifter. Also my guess is the number 4 cylinder push tube was bent before it threw a code for it not after the #5 was fixed and the truck was running.

 

If the head stud job was done without lifting cab or pulling motor it doesn't suprise me that this happened, the advantage of pulling the motor is you can see everything you are doing and are able to check everything out real good plus you can pull the oil pan to clean that too before you reinstall, you can't just drop these pushrods in and expect them to be seated properly, I've seen a couple of these that broke the rockerarms in addition to bent pushrods.

 

There are 20mm and 18mm dowels. Some blocks are 18, some 20. Some heads are 18, some heads are 20. Anything after like mid 06 is 20mm. Earlier trucks (like an 03 or 04) that would go in for service work would get 20mm heads if a head needed replacement. You can not just use a 20mm dowel gasket on an 18mm head, it doesn't work like that. You need the corresponding gaskets for the heads. Every headgasket kits comes with stepped dowels though for going from 18 to 20 and vice versa. There are a few other differences in there too, but the right gasket needs to be used. The gaskets themselves are not universal, no. You can't put an 18mm gasket set on a 20mm head, it just wouldn't fit. You could however, accidentally, put a 20mm gasket on with an 18mm head setup, it would be loose and sloppy on there.

Make sense?

 

yeah that makes sense the gasket that was bought was stated as a universal oem gasket for both dowel sizes so it was a 20mm hole size. When doing reseach on the repair the truck owner was advised to stay away from the black onix gaskets unless you plan on taking the heads off again. why, IDK.

Either way the truck is now up and running great both #5 and #4 push rods were bent due to not being seated in lifter and only a #5 code was thrown for future refrence.

thanks again guys for your help hopfully we wont have to be messing with the heads again anytime soon.

 

Yeah, the black onyx are junk, they're too thin. They're too thin even before being compressed. There have been many failures with them. OEM is the way to go for sure. For future reference, order the correct size gaskets according to what heads you have.