Here's where we took it apart and found the worn down lifter. @SUBURBAN5 is your engine a Vortec or TBI - been meaning to ask. IIRC you have a Vortec so, your lifters are roller not flat tappet like in my post.
https://www.gmt400.com/posts/1123039/
Suburban down.
- Thread starter SUBURBAN5
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Here's where we took it apart and found the worn down lifter. @SUBURBAN5 is your engine a Vortec or TBI - been meaning to ask. IIRC you have a Vortec so, your lifters are roller not flat tappet like in my post.
https://www.gmt400.com/posts/1123039/
Hipster
I'm Awesome
A bent pushrod can indicate something made contact. Retainer to guide, a seized valve stem, piston to valve, valve spring coil bind. Retainer to guide contact can crack a guide.
You have locking adjusters. They don't usually just loosen up and start clattering. It they were too loose would have been clattering from the get go, too tight and it would have been holding the valve open so something else was going on before the stud let loose.
You questioned the original build quality so I think I there is more going on then just a broken stud and enough info present to warrant some investigation. Are the pushrods of quality to handle the spring pressures you're running?
Harmonics and vibration can break a lot of stuff. Work hardening and fatigue to a failure. No different then a bad harmonic balancer breaking a crankshaft or the old Harley that vibrates so badly it breaks everything bolted to it.
Look for other damage. Check out the spring set up and clearances. Pull the intake and check the cam and lifters. The broken stud is just a symptom of another problem.
Your post indicates this happened after you did a valve adjustment. What was the reason for that?
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Hipster
I'm Awesome
Whatever it is - unless my eyes deceive me, it has alloy heads.
Yeah, with the big spring pockets definitely some type of aftermarket heads and one of the reasons they need checked. Unless the source is known could have been bare castings built by some fleabay builder piecemeal.
Ok all good points. So the pushrod doesn't look bent to the naked eye. But when I rowed it on a flat surface you could see it wasnt rolling flat . Literally a tiny light gap was present just to clarify.
Also I was about to adjust the lifters but never did. It broke before I tried that.
When I get home I'll see if I can locate the brand of the pushrod.
I dont mind jumping into it deeper to see what's going on but unfortunately my knowledge is very limited on correct parts or signs of causes. It will be the first time I undo the plenum too. I look at the cam that's all I have to take out right? Or does the intake manifold have to come off?
Thanks again for all your help
Also I was about to adjust the lifters but never did. It broke before I tried that.
When I get home I'll see if I can locate the brand of the pushrod.
I dont mind jumping into it deeper to see what's going on but unfortunately my knowledge is very limited on correct parts or signs of causes. It will be the first time I undo the plenum too. I look at the cam that's all I have to take out right? Or does the intake manifold have to come off?
Thanks again for all your help
Wow I wasnt really looking forward to tear it completely apart lol. Any other maybe shortcuts?
Hipster
I'm Awesome
This isn't about not wanting to dig in deeper it's about finding the root cause of the problem so it doesn't happen again or continue to do more damage. It's already been said that the intake needs to come off and the lifter pulled out of it's bore and the lifter and cam need to be inspected. The cam doesn't have to come out for this. A visual check will tell you if a lifter or the cam is in the process of being chewed up.
Slightly bent is too much. That pushrod is now junk.
If the cam and lifter are wiping out it can send metal through the engine and wipe out the bearings. Skipping this check can cost you quite a bit of machine work and a more costly rebuild so don't skip checking the cam. The valve spring set up is not as critical if you drive around like grandma never seeing the high side of 3k rpm, but it's extremely important if you like to romp on your stuff. Now you're familiar with it.
You noticed a problem and continued to drive it for 2 more days possibly doing more damage. Putting in a $3 rocker stud and the "slightly" bent pushrod to try without checking anything else is not the way to handle this, but it's the answer you're looking for.
We live in the information age. Download a service manual, google it, you tube videos, THIS SITE with plenty willing to help. Educate and familiarize yourself with the information you need. You need to look at the pics Playing with TBI posted. Rollers can flat spot from impact or lock up and chew up the cam just as well.
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Knuckle Dragger
Rascal *****
I'm no where close to an engine expert but for sure you gotta slow your roll a bit. It's a PITA now but man you be even more pissed and behind the 8 ball if you half ass it deliberately or out of haste and it fails again. Is this a daily driver?
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