I am replacing exhaust manifold in 02dakota .Which grade bolts are best to use since this is a common problem with them breaking off ? Does anyone know what grade the manufacturer used originally that had trouble ?
Is 10 ok to use ?

 

The issue isn't the bolts being weak and breaking off, it's the bolts seizing in the head and being rusted and breaking. I'd say copius amounts of anti-seize on a grade 8 or higher, or stainless steel bolt.

 

I'll second that. My "Original" bolts broke. Anti-sieze so even if they do break it will make them give up a little easier coming out of the head. I made my own out of grade 8 and they seem to be holding up fine. Sometimes just too impatient to order parts when trying to finish a job.

 

Thanks .I will go with the 10 an plenty of antiseize. So the issue most have with this isn't so much the thickness as it is the seizing ?
Im having to possibly drill out 1 broken bolt if removing manifold around it doesn't give me more access to it to unscrew it.
Any tips on getting bolt out easier?
​​​​​​​And what torque do new manifold bolts need to be ?

 

be sure to NOT use plated blots. the plating can come off when hot. and do torque the bolts to 70-80% of full torque the first time. then re torque to full torque after 10-20 heat cycles.

 

I got the bolts from the dealer, that way you get the double-enders that hold the shields.

Always surface the manifolds before installing.
The ECM strategy will cause the manifolds to overheat under certain conditions and the manifolds then warp which causes the bolt breakage.

 

weld a nut on the broken stud...drilling is a nasty, slow way to extract. a mig welder works much better even if the stud is broken flush or below the head surface. place the nut over the stud and weld through the hole in the nut and fill up to the nut.

 

I managed to drill out old bolt that was seized inside even a left-handed bit w heat wouldn't get it out but it did drill out fast w left drill bit.I was able to retap to same size since I got out old bolt edges after drilling thru inside of bolt.
The bolts I have do have that zinc plating over them an are grade 8(10 were different thread)
What problem will that give me?
An what do I need to do to the surface besides clean it up an check that it's even?
I don't want to go back to dealer screws an I have 2regular short ones an 2 longer ones with nut spacers then the heat shield an cap.Will that give me any issues with torque later on an loosening?
​​​​​​​thanks

 

Here is pic after getting bolt out on left side of double manifold