collapsed lifter?
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
collapsed lifter?
I was attempting to adjust the hydraulic lifters/valves on my '74 smallblock when I ran across something that I think is probably much more than a $%&* nuisance.
One of the lifters feels "spongy". I can shove the pushrod down with my fingers, and it rebounds right away. It is difficult to feel the "zero lash" position, and easy to blow right past it.
What's up with that?
One of the lifters feels "spongy". I can shove the pushrod down with my fingers, and it rebounds right away. It is difficult to feel the "zero lash" position, and easy to blow right past it.
What's up with that?
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
I was attempting to adjust the hydraulic lifters/valves on my '74 smallblock when I ran across something that I think is probably much more than a $%&* nuisance.
One of the lifters feels "spongy". I can shove the pushrod down with my fingers, and it rebounds right away. It is difficult to feel the "zero lash" position, and easy to blow right past it.
What's up with that?
One of the lifters feels "spongy". I can shove the pushrod down with my fingers, and it rebounds right away. It is difficult to feel the "zero lash" position, and easy to blow right past it.
What's up with that?
Fixing it is a different story, sure-fire method means pulling the lifter apart.
Search it through and you'll find many many sites with suggestions on all kinds of possible solutions (marvel mystery oil, etc) your mileage may vary
M
here's a pic
With that little check ball stuck open, the oil leaks back into the body of the lifter so what your feeling is just the little spring underneath. With teh checkvalve working, (and no pressure) it traps the oil under there and acts like a (sort of) solid block and resists you pushing down on the rod.
Last edited by Mooser; Sep 16, 2013 at 11:09 PM. Reason: found a pic
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
It is VERY easy to blow past the 'zero lash' point if the lifters are not pumped up with oil. That's why I use the "jiggle" or "shake" method of finding that lash point, rather than the "spin" method.
If you shake the pushrod up and down as you are tightening the adjustment screw, you can easily find the place where there is NO SLACK left. That is the Zero Lash point. The pushrod rattles as you are shaking it; when the rattle disappears, you're there.
If you shake the pushrod up and down as you are tightening the adjustment screw, you can easily find the place where there is NO SLACK left. That is the Zero Lash point. The pushrod rattles as you are shaking it; when the rattle disappears, you're there.
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
I can't see how anything other than managing to get air in there somehow or a stuck check ball can result in the spongy feel as you described. I've had it before and took the lifters apart and checked them, stupid little ball stuck open in the cage.
Even went back and forth with Lars trying to see if there was anyway to bench test them, doesn't actually seem practical.
Do the very best to set the lash as you are and live with it. There is a chance it'll free itself after awhile.
Otherwise, blow it all apart and clean it and put the same lifter back in the same hole.
M
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Before I install hydraulic lifters, I stick them in a can of motor oil and use a pushrod to pump each one a few times to fill them with oil.
Some folks say it's not necessary; but it's not much trouble for a little extra 'insurance'.
Some folks say it's not necessary; but it's not much trouble for a little extra 'insurance'.
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
Not to beat the subject to death, but....
It seems that I feel two different spring rates. At first, the resistance is very light, and then at some point as I turn the adjusting nut down, the resistance increases dramatically, and the valve begins to open. If I stop there and wait for a minute, the valve will close again as the lifter slowly adjusts itself to the preload. (I am filling the cylinder with compressed air with a leakdown tester at the same time, so I can tell).
That can't be right, can it?
It seems that I feel two different spring rates. At first, the resistance is very light, and then at some point as I turn the adjusting nut down, the resistance increases dramatically, and the valve begins to open. If I stop there and wait for a minute, the valve will close again as the lifter slowly adjusts itself to the preload. (I am filling the cylinder with compressed air with a leakdown tester at the same time, so I can tell).
That can't be right, can it?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Burning Brakes
Joined: Aug 2008
Posts: 878
Likes: 55
From: Deep South Denmark
Not to beat the subject to death, but....
It seems that I feel two different spring rates. At first, the resistance is very light, and then at some point as I turn the adjusting nut down, the resistance increases dramatically, and the valve begins to open. If I stop there and wait for a minute, the valve will close again as the lifter slowly adjusts itself to the preload. (I am filling the cylinder with compressed air with a leakdown tester at the same time, so I can tell).
That can't be right, can it?
It seems that I feel two different spring rates. At first, the resistance is very light, and then at some point as I turn the adjusting nut down, the resistance increases dramatically, and the valve begins to open. If I stop there and wait for a minute, the valve will close again as the lifter slowly adjusts itself to the preload. (I am filling the cylinder with compressed air with a leakdown tester at the same time, so I can tell).
That can't be right, can it?
The lifter is in the "down" position and the oil can be forced out of the oil passage that the oil normally enters when the engine is running and the oiling system is pressurized. That's how the hydraulic lifter takes the slack out of the system. The check valve does close but it isn't, and shouldn't be, perfectly tight so without oil pressure from the pump some oil will get past the valve.
The answers given to you by Mooser are basically correct, but only under the right circumstances!
Normally the lifter should be filled with oil when you stop the engine and should not feel "spongy"; however once you tighten the adjusting nut past the point of just taking the slack out of the pushrod then you will force the oil out of the lifter and only the spring will be left to hold the pushrod up. Hence the "spongy feel", or perhaps we should call it the "springy feel"
Lots of folks will tell you how easy it is to adjust hydraulic lifters. That's true if you are used to doing it (like with everything else) but for first timers it really is quite difficult. The "shake up/down" method described by 7t1Vette is safer to use for amateurs like us. Tighten the nut bit by bit while moving the pushrod up/down.
Regards
Karsten
Last edited by Danish Shark; Sep 19, 2013 at 12:10 PM.
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
So what you are saying is just that particular lifter is behaving that way because it is only partially filled with oil? And that's why I can shove the pushrod down partway with my fingers?
So once the engine is started, the lifter will fill with oil and run fine? What has me concerned is that it is only the one lifter that feels that way. All the others have a very definite stiff/loose point.
So once the engine is started, the lifter will fill with oil and run fine? What has me concerned is that it is only the one lifter that feels that way. All the others have a very definite stiff/loose point.
Burning Brakes
Joined: Aug 2008
Posts: 878
Likes: 55
From: Deep South Denmark
So what you are saying is just that particular lifter is behaving that way because it is only partially filled with oil? And that's why I can shove the pushrod down partway with my fingers?
So once the engine is started, the lifter will fill with oil and run fine? What has me concerned is that it is only the one lifter that feels that way. All the others have a very definite stiff/loose point.
So once the engine is started, the lifter will fill with oil and run fine? What has me concerned is that it is only the one lifter that feels that way. All the others have a very definite stiff/loose point.
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
I was thinking of getting an oil pump priming tool, spinning up some oil pressure, and seeing if that changes/improves things. Because I'd hate to tear the top off the engine for no good reason.
Whaddya guys think about that?
Whaddya guys think about that?