Hello all, Havent been on for ages and have a question for someone. Have been digging out broken studs from the heads of a 3412 (exhaust) with the aid if the Cat broken stud remover and realized that the kit is for 3/8 studs and mine has 7/16 thus I had to make more inserts for the cat tool to work. My question is was the 7/16 stud an update or a mod? The original stud is a 4S6137 ( 3/8 ) but now are 7/16 UNC. If the 7/16 is an update does anyone have a part number? Thanks in advance.
Need to do some research, What's you serial number?
They might have 3/8 NC heli coils in them. Later Bob
sorry guys been a bit tied up. Serial number is 14Y01036
I don't see anything that has changed the part to 7/16. Sounds like it could be the heli coil as Bob mentioned
Either I'm too dense for this one, or you have your fractions messed up. I can't see a 7/16" stud going into a 3/8" hole, unless it was tapped out, not heli coiled.
Maybe call the CAT dealer, they should be able to shed some light
Thanks for the replies. I will talk to the dealer about 7/16 studs and I am putting new manifolds on it so will have to drill them out too. It is a job that certainly tests your patience!
I have not had any luck finding any reference to a stud up grade to 7/16-14. My only guess is someone did this because they had had a problem in the past. I know the older 3408 engines had a problem with broken studs and the "cure" was to open up the holes in the manifold, stronger studs and special gaskets to let the manifold move around with changes in heating without breaking studs. Think they may also have made studs and spacers longer to give more of a "sring" effect on the studs. That being said I was able to find just three different length 7/16-14 tapelock studs in the Cat system. They are as follows: 9M5082--42.5mm long 4L3755--50mm long 2W3551--90mm long Never really understood why Cat gives inch size hardware in metric lengths???????
Yeah 3412 in 773,s got a bellows manifold to help with the expansion but they were the worst suffering of all 3412 due to the duty cycle a truck see,s (cooling down while loading, high temps on the haul and cool on return especially if a downhill haul to the pit) There has never been an upgrade to 7/16 by Cat, someone would have had the threads damaged and taken it up to the next size, basically your on your own.
If u can get the studs out match the thread mayb u could go arfter market studs or bolts or run heli coils to bring em back down so u don't have to alter the manifold