hey guys...
i need some of the pros to give me some incite...

at NEST tech day we helped a "new" friend install injector cups and some other under the cover parts. last nite about 11pm we finally were ready to fire...the truck was beating like a bass drum. i think my neighbors thought it was july 4th. anyway...i stopped him and called who ever i could think of at 11pm on a sunday...after talking, a few suggested starting till it would idle and see if the sound changes...we did, but the sound was the same...shut it down. called ppl back, decided to pull VCs and retorque rockers. they were all fine and now its like 1215am...he lives 2 hrs away, and i have to teach in the am. i was looking and looking for something wrong...found a push rod that didnt look right. pulled the rocker and we found a metal candy cane...well obviously it is still in my garage and we will fix asap...here is the question

what steps or things do i need to check to make sure a new rod wont do the same thing? we turned it over by hand without GPs, after using mity vac. immediately upon cranking the bang started...truck wouldnt fire(due to air) when it did banging still present. after finding bend rod, we removed GP from that cylinder and turned motor over with a coat hanger in the GP hole. Not one ounce of fluid came out. i also tried to "feel" if there was something that fell in to chamber and would hold up the valve. hard to tell if there is anything in there though.

please help me make sure this will not happen to the new rod...all and any help/suggestions will be appreciated and considered.

 

I have never had the pleasure of replacing cups (yet) but I presume the rockers come off during the process? If so, what process did you go through when re-installing the rockers? Did you place the mark on the damper to the 11 o'clock position or did you install some sort of makeshift degree wheel and manually rotate the engine so each cylinder was at TDC on the compression stroke before installing the rockers for that hole? From what I've read, either method will work.

 

I know you didn't touch the valve or valve spring but I'd just take the valve spring compressor you have and compress the spring wherever the push rod bent and see if the valve will move by hand to ensure that valve itself is operating as it should. Just one of those things I'd do if it was me.

 

Like to see how this one comes out. I wish you a speedy fix. Keep us posted.
Chet

 

i didnt have the pleasure of doing the whole job...had lots of large projects which needed help...i was with him and helped put it back together(VCs, coolant, oil, etc) i dont think the rockers were installed in either fashion. im also not sure that needs to be done. when i did my springs, we did that so the valve didnt fall down...but they never touched the valve. just rocker hold downs and push rods. i would like to learn more, so we can make the truck right. so i ask, is that the correct procedure, or is it ok that they did it without rotating?

 

here is a pic of the push rod...dont know if it helps diagnose...

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I believe the manual says to rotate the engine so the mark on the balancer is at the 11 o'clock position. (I am pretty sure I read that somewhere....) That must be the position where none of the valve springs are under any sort of pressure so the rockers can be removed and re-installed without issues.

Seems to me like it would be pretty easy to bend a push rod while trying to re-install the rocker arms when the cam lobe is at partial lift. Valve train geometry is exact science so a little bit of an angle can bend a rod quite easily. I think I would consider pulling all the push rods and check for straightness, replace any that are bad, re-install (with balancer at 11 o'clock) and fire it up.

Maybe someone with more specific 7.3 engine building experience will chime in and clarify.