Vortec 4.3L v6 Rocker Arm Issue Please Help!
 

Hello everyone Im new here, and Im hoping someone can help me out. I have a 4.3 vortec in my boat was a replacement for the Volvo penta in the boat. Prior owner partially submerged the engine and took water in the engine. Long story short, we disassembled to the block, got the water out, new gaskets from the block up, Intake manifold was cracked (which was allowing water in) replaced it, got it timed and it ran rough for a bit, took off valve covers, notices we bent 9 push rods, due to over torquing bolt on the rocker arms, now they dont have studs with a nut, just bolts. We pulled the lifters which have rollers, they seem ok, oiled the lifters before we put them in ,we reassembled with new push rods, new push rod guides and torque says 10 ft pounds on the rocker Bolt after the lash is out of the push rods go a half turn. Well we do this and follow the firing order then rotating and tighten the other rockers as the book says, and no matter what we do the bolts come loose on 3 or more rocker arms. I belive this engine is a 2003 model un sure if its a marine engine but the prior owner says it is. But it has bolts in the rocker arms not studs with nuts. Maybe the threads on the head for the bolts stripped? I don't know. We have disassembled and reassembled this 3 times, Im fed up. Anyones Knowledge will be greatly Appreciated. Thanks, Derek

This may help , sounds like the guy befor you had problems and replacedthe old studs with bolts if I understood you post . Ithink your rocker arms are moving out of their holes . If this is the case they wer not tapped correctly. I had the same problem but the studs on my motor seemed to pessed into place I was surprised because you would think they would be threded. any way I went to a machine shop they had some studs that had a larger diameter but the other end where the rocker arm attaches to remained the original standard size was able to use the same standard nut size hpoefully this will help. Matt

Thanks, I think these engines came with bolts instead of studs after 2003 according to the S-10 manual. I was thinking of helicoils in the threads on the heads. I would hate to do all this and it still has issues though.