Hydraulic lifter Collapse?
 

I went to adjust the valve lash on my SBC 350 today. One of the rockers required much more tightening to eliminate the clicking than the others. In other words, the amount of exposed thread above the adjusting nut was much greater than on the other rocker studs.
I wonder what could have caused this.
I would appreciate you thoughts on this.

Re: Hydraulic lifter Collapse?
 

There is a good chance the stud has pulled out of the head.

Re: Hydraulic lifter Collapse?
 

Thanks for your comment, However, heads are Edelbrock E Street and i don't think the rocker studs screw directly into the heads. There is a plate for each cylinder on the head with a rocker stud on each side of the plate.. There is a bolt on each side of the plate that secures the plate to the head.

I will check this tomorrow.

Something's not right

Re: Hydraulic lifter Collapse?
 

The plates should be push rod guide plates that are required with aluminum heads, so you are correct that it would not pull out. Flat tappet cam? I'd be worried you wiped a lobe.

Re: Hydraulic lifter Collapse?
 

The lifter has most likely either collapsed or has junk in its sealing valve...or, the lobe has died and lost its lift ramp....
Either way, flat lifter cam or roller lifter cam, its to to pull the manifold and distributor...and remove the offending lifter...

Roller cam...if the roller on the bottom of the lifter is intact, the internals of the lifter is faulty and the lifter needs replaced. If the roller is locked up or missing...you will have to pull the cam and replace all lifters and the cam.

Flat lifter cam...remove the lifter and inspect the bottom surface,,,,it is most likely tore up...if it is...time for new cam and lifters...if the bottom is still ok, the internal valve has collapsed ...replace the lifter if the cam lobe looks ok...

:chevy::gmc2::chevy::gmc2::chevy:

Re: Hydraulic lifter Collapse?
 

If you adjust all the noise out and it returns in a short period (2 to 4 weeks) I would suspect the same.

Fuel mileage will absolutely go less that 6 mpg also. Even with these things I would still have movement on all the rockers when running. Certain valves on this engine were sunk over 3/16ths of an inch when the heads were pulled. Its hard to diagnose with even a compression test, use your best measurements and trust your gut.

It may be something else collapsing like a pushrod.

Re: Hydraulic lifter Collapse?
 

Aflter you made the adjustments to that one, could you see any movement of it while the engine was running. Only other way to confirm I would confirm the lobe is ok is to set up a magnetic dial indicator above that rocker and spin the motor by hand to measure the lobe somewhat.

Im about to run marvel oil in with my regular oil to help with lifters on the 71 gmc i just bought. before i make any adjustments. Hoping this will wake up any stuck lifters first.

Re: Hydraulic lifter Collapse?
 

I would try this before Marvel Mystery Oil, Lord only knows whats in that stuff today as the EPA can regulate them and force them to change compounds in it.

Its been going on for years.

https://www.amsoil.com/shop/by-produ...code=FLSHCN-EA