This is a friends jeep,
He had developed a definite miss. After much trouble shooting etc he found a broken rocker arm stud. He checked everything for binding, sticking, galling etc. And replaced the rocker stud all good again. Or so he thought ! Then after driving less than 50 miles, YEP a Dead miss, Found a second rocker stud broken. (different location). When he opens it up there seems to be nothing binding, nothing stuck etc. everything moves freely....

What could be going on here ?

 

What engine? 4.0's have bolts and 4.7's don't have anything.

 

Inline 4.0 6cyl.
He said this will be the 3rd time he has developed trouble and found a rocker bolt broken. I asked him to bring me the bolt to look at...

 

The only way I can see that happening is if a high lift cam was installed without checking the rocker pivot clearance or the pushrods are too long. OEM pushrods are 9.650" long.