4.3 valves backed off

[prlwng]

Went thru top of 4.3 12 bolt manifold, set vales at zero lash plus 1/2 turn. Finally warmed up enough to run on muffs. After about 15 minutes valves started clacking. Went back jnto and found nuts had backed off a couple valves.

Anyone know of a reason for these to do such?

Would appeciate it as still have not put valve cover back on.

Water drained again as gonna be down into 20's again.

Oh reason to go into it was mechanic did not do intake gasket right when replacing cracked head. Had water in oil. At least now no milkshake after this run.

 

[GA_Boater]

Have you re-torqued the heads after a heat cycle or two?

 

[Scott Danforth]

Could be having a rocker stud or two coming out

 

[prlwng]

Spacing for threads above nut very close to all the same. Also same as original set. Did do a head bolts check and t wrench never moved anything.

Reason for resetting valves was found a washer? Under a nut. Y4 I do not know but had no compresson on that cylinder. Valve held open.

 

[jimmbo]

New rocker arm nuts might be an answer. I know every one does the tighten till the clacking stops, then 1/2 - 1 turn more, but that is not what the manual states

The manual basically states the when the lifters are not on the cam lobe or the ramps, the adjustment is...
Turn the valve rocker arm nut clockwise until all the valve lash
is removed (zero valve lash). Zero valve lash can be felt by
moving the pushrod up and down between you thumb and forefinger
until there is no more up and down movement of the
pushrod.
• When all the valve lash is removed, then turn the valve rocker
arm nut clockwise 1 additional turn (360°)

I believe that is assuming the lifters are full of oil

 

[prlwng]

New nuts is one thing I was wondering about. Will see if can pick some up tomorrow. Thanks.

 

[Lou C]

New rocker arm nuts might be an answer. I know every one does the tighten till the clacking stops, then 1/2 - 1 turn more, but that is not what the manual states

The manual basically states the when the lifters are not on the cam lobe or the ramps, the adjustment is...
Turn the valve rocker arm nut clockwise until all the valve lash
is removed (zero valve lash). Zero valve lash can be felt by
moving the pushrod up and down between you thumb and forefinger
until there is no more up and down movement of the
pushrod.
• When all the valve lash is removed, then turn the valve rocker
arm nut clockwise 1 additional turn (360°)

I believe that is assuming the lifters are full of oil

That's how I did mine when I replaced the cracked heads and I did not have any change in valve noise after running it.
The washer under a nut is very suspicious though, maybe someone else before you had this problem before....

https://www.dropbox.com/s/55j6h4dd1u..._2273.MOV?dl=0

 

[Bt Doctur]

try installing the nuts only on the studs. If you have no resistance the studs or nuts are incorrect.You should not be able to tighten the nuts very easily, Happend to me, got new heads with the wrong studs and the nuts could be tighten with your fingers.

 

[prlwng]

Ok, yes, the nuts can be turned down to no lash with fingers. Or at least very close to no lash.

What may be the solution please. New studs, or new nuts? Or both?

Have never had to replace studs, but then first time into a v6.

 

[alldodge]

Rock auto has rocker nuts, Sealed Power of 0.31 each and Melling for 1.01 each

 

[scoflaw]

Washer under the nut could be a sign the stud is pulling out, especially if the exposed threads all look about the same.

 

[Lou C]

Yep if you look at them closely, they are kind of like a locking nut, they should not back off easily. It could be someone lost a coupler doing the last work done and then used regular nuts.

 

[Grub54891]

Same thing happened to a buddy's truck. New nuts solved the issue.

 

[Bt Doctur]

Most likely the studs but can also be checked with a new nut. To remove the threaded studs double nut the stud and unscrew it