Thread: hydraulic lifters always seem solid ???

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Hi Guys,
I still haven't really figured out this problem I have with my hydraulic lifters. The engine is a fresh rebuil, was broken in correctly and has about 5000 mls on it. Its an old 350 SB though, from before 1986 (no electronic stuff).

My lifters always seem solid and don't bleed down anymore after about 300 mls of driving. Then I have to take them out, empty them, clean them, put them back in again, set all the valves and off it goes like a rocket, drives absolutely fine for about 300 mls, then I have the same problem. The lifters act as if they were solid, and if I try giving them some preload, that will open my valves before the lifters compress. (I already have double valve-springs) This happens equally on all 8 cylinders. A friend of mine said I might be running too good oil. I have 10W40 High-Grade Liqui-Moly with MoS2 additiv. Damn expensive, but said to be very good. My friend said I should run thicker oil, something like 10W30, because the thin stuff runs through the engine without staying on anything. Can that be true? Will that affect my lifters? The lifters are almost new and show virtually no signs of wear, they don't bind mechanically, it's just the oil pressure in the lower compartment that keeps them up all the time.
The lifters do compress slightly when the valve is fully open and the engine is running, but not as much as they should do and the preload keeps the valves very slightly open at ALL times, which is not a good thing.
Who can help me? Thanks a lot,
MadMax

The lifters are always going to feel "solid" when they are properly adjusted and filled with oil. You cannot compress a liquid. If they are compressing at full lift they are bad.

You are trying to preload the lifter after it has been run?

The only way you can do this is with the engine running. If you tighten the rocker nut it will open the valve slightly... but this will pump down in a couple of cycles.

Your problem is not the lifters. It is your mis understanding of how they operate, and their adjustment. They will only take up the lash that is present.
If you try to tighten the lash they will hold the valve open for several cycles till they bleed down and there is "0" lash again.

Proper adjustment puts the inside push rod seat just below the retainer ring. (approx 1/32- 1/16).

Thanks Bob,
I'm fairly new to building engines and I know that the lifters can't be compressed when full. BUT They don't bleed down in a couple of cycles, they stay solid and keep the valve open AT ALL TIMES. Even when the engine is running. I got virtually 0 compression on all cylinders even after a few 100 miles of driving, because the valves are always slightly open. And I know what preload to set them at, and that preload has to be set with the lifters empty. But that doesn't change my problem that the lifters don't bleed down enough. Maybe I should try getting stronger springs.

But let's suppose you are completely right. I have these symptoms:
-Engine works well
-drive 300 mls
-engine loses power, gets hot uses lots of fuel
-after 500 mls engine runs very rough, so rough that the tranny doesn't shift anymore, hard starting,...
-disassemble engine, clean lifters, put it back together again (don't change anything else)
-engine runs fine for 300 mls...

What else could that be? Can it have something to do with wrong viscosity oil?

Originally posted by MadMax
They don't bleed down in a couple of cycles, they stay solid and keep the valve open AT ALL TIMES.

Even when the engine is running.

Are you adjusting the rockers while the engine is running, @ operating temp? Am I missreading your post?

Walk us through the proceedure you are using to set the valves .... step by step.

I use the following procedure to set my valves:
With the engine cold I turn it by hand til the exhaust valve of the cylinder I'm working on starts opening, then I tightend down the inlet valve til I have no lash, then a half turn more. Then I turn the engine further by hand (always normal direction of rotation (clockwise when looking from the front at the engine) wait for the inlet valve to open and just before it's fully closed again I set the exhaust valve to zero lash plus a halfturn. And as I said, it runs perfectly for a few hundred miles. I'm going to check on different oil (same stuff a friend of mine uses in his 350 SB) Let's see how far that gets me.
But different question: You say that the lifters don't compress anymore once they're fully pumped up. Then precisely when in one valve opening cycle should the lifter begin to open the valve?
I always thought the lifter should compress fully with the valve still completely closed, then with the lifter resting on it's base the valve should open and close and only when the valve is fully closed the lifter should be let up again, sucking in oil through it's eyelet. That's what I thought a lifter cycle should be, but please correct me if I'm wrong. I took the valve setting sequence right from the CraneCams homepage. What oil do you use?

Originally posted by MadMax
I use the following procedure to set my valves:
With the engine cold I turn it by hand til the exhaust valve of the cylinder I'm working on starts opening, then I tightend down the inlet valve til I have no lash, then a half turn more. Then I turn the engine further by hand (always normal direction of rotation (clockwise when looking from the front at the engine) wait for the inlet valve to open and just before it's fully closed again I set the exhaust valve to zero lash plus a halfturn. And as I said, it runs perfectly for a few hundred miles. I'm going to check on different oil (same stuff a friend of mine uses in his 350 SB) Let's see how far that gets me.
But different question: You say that the lifters don't compress anymore once they're fully pumped up. Then precisely when in one valve opening cycle should the lifter begin to open the valve?
I always thought the lifter should compress fully with the valve still completely closed, then with the lifter resting on it's base the valve should open and close and only when the valve is fully closed the lifter should be let up again, sucking in oil through it's eyelet. That's what I thought a lifter cycle should be, but please correct me if I'm wrong. I took the valve setting sequence right from the CraneCams homepage. What oil do you use?

Try this procedure for your hydraulic lifters. Take 1 valve cover off. Start the engine, and get it to operating temp. they make clips that snap on the rocker to keep the oil from spraying all over. Or you can modify an old valve cover cutting access holes in it to get at the rockers. Anyway ......... once it's a operating temperature, loosen each rocker until it clicks. tighten it back down just until the click stops. Then give it an extra 1/2 turn. Do that with the rest intake and exhaust alike. Then do the other side the same way.

If I'm understanding your procedure right, you are bottoming out the lifters (Too Tight)

Also I always set the lifters when the engine is at operating temp. Not cold. Metal parts expand and contract, so you want them set at the temperature they will be operating @.

A hydraulic lifter does not "bleed off as it rises to open the valve. The plunger does not move in the lifter. It is forced to stay in one position because it is setting on a locked (due to internal valve) hydraulic column. As soon as the lifter moves up, the valve moves up. "0" lash. The lifter plunger keeps moving in its bore only to take up wear. It will move only till it reaches the snap ring.

There is usually more than !/4" travel in the Small block Chevy lifter. So if you set the lifter plunger at the bottom of its travel, you would have adjustment ofr 1/4" of wear before things get noisy. But, no room for expansion of metals at operating temp. That is why the plunger is usually set about mid travel and higher for hi-perf use. This allows the lifter to adjust to the proper "0" lash.

A hydraulic lifter will not over fill or "pump up" during normal operating use. Only when rpm gets high and valve springs are weak will the lifter "pump up" and hold the valve open..

Even then the lifter is not actually pumping up from oil pressure. It is merely adjusting to the increased lash caused by the lifters not following the cam, pushrods doing the Hula and the valve springs bouncing around. Thats why when the rpm comes down, the lifters go back to working like before, to the original setting, as they only maintain "0" lash.

the ? is though why does the motor run good for 300 miles. if the motor run good for 300 miles why would the lifters tighten up then, if anything mine always get loose , but madmax changing the oil is not going to help eather. when the motor starts to loose power can you back off of the lifter adj. and make the cylinder hit then?
i just thought about this, but a few yrs ago i had a valve job done on a head i had and the guy knurled the valve guides to tight and after the motor got hot the valves would stick open, not wide open but just enough so it wouldnt build up any comp. and the motor would loose all power, but by the time we got it back in the shop it would have cooled down and the valve would be shut when we checked them. after about a week we found out what the problem was, but im happy to say they never found out who killed the guy that did the valve job.

That's interesting, I have had a valve job done, maybe another guy's gonna loose his life soon :-) No, I don't think it's that because as far as I can recall it wasn't the full job, only regrinding the seats and angleing the valves, no new guides were installed.
And another thing: I thought that if you set the engine cold it doesn't matter as long as you have hydro lifters, becasue they take up all the preload you give them. ???
What I want to know is: When does the plunger move in the lifter? If it doesn't move except to take up the wear in pushrods and valvestems, how can it pump oil up the pushrod? But I'll put it together again today and let you know how I'm getting on.
Thanks a lot so far guys!

The lifter doesn't pump oil. It just lets the oil under system pressure (engine oil pump) pass thru to the pushrods

I thought that if you set the engine cold it doesn't matter as long as you have hydro lifters, becasue they take up all the preload you give them. ???

Not true. There's only a limited amount of travel. That's why the instructions always say "take up the slack, then add a half turn." Valve adjustment ALWAYS matters. One of the primary reasons for hydraulic lifters is lack of noise. The hydraulic design keeps all of the parts in contact with each other all the time, so there's no clicking as with solid lifters. Also, the adjustment process is a little more forgiving.

You can lash the valves either hot or cold, but the preferred method is hot. Loosen each one until it clicks, tighten it until the click goes away, then add a half turn. (Some folks use 1/4 turn, 3/4 or a full turn.)

madmax, i think youve got hungup on these lifters somewhere along the line and cant see the forest for the trees, these people are telling you the correct way to adj. the valves and if you do this correctly i dont know how they could build up to the point the valve wont close, but run fine for 300 miles. if you adj. your valves and the motor runs for 300 without any problem and then start to run bad id be looking somewhere alse other than valves for the problem like maybe a fuel problem. get the motor running good again and then check the comp. on a cylinder thats easy to get to and when the motor starts to run bad the next time check the comp. again on the same cylinder and if it stays the same the lifters are ok, then you can check something else. let me know about the comp. thanks, mike

Hi Guys,
I have set my lifters now with the engine hot, much better. The slight roughness is proabably caused by the outside ring of my damper has slipped slightly. Now I'm getting good compression and it runs smoothly enough, guess that will be just fine when I get my new Damper. Thanks a lot!
(I always thought setting the lifters when cold was far exacter, but that never got it to run this smoolth :-)
Thanks to all who helped me!
MadMax

Glad it's runnin' better. Let's see if it makes it past 300 miles now.

Hi MadMax,

I had my cylinder heads replaced on my '94 Ford Taurus V6, and afterwards the hobbyist mechanics couldn't get my car to start! They were desperate for two weeks. Today it turned out that the lifters were stuck in an extended position (i.e. hard with insufficient bleed-off), so that they kept all the new valves slightly open.

The solution was to remove the lifters, compress them carefully with a tool and make them "movable" again. I read a lot about this phenomenon today, and here is my understanding of why a lifter can eventually get stuck like that:

- Oil gunking up inside the lifter and limiting bleed-off
- High viscosity oil that bleeds slower

Interestingly, I also was running on a higher viscosity inexpensive oil, 10W-40 instead of 5W-40, because I thought it would protect the 130,000 mile engine better. I think that might have something to do with the fact that my lifters wouldn't bleed.

Another related phenomenon that I now understand is lifter "pump-up" at high rpm. It happened to me, too: When I tried to gun the engine, suddenly it would stall, falter, and recover over 5 seconds. That's because the lifters were starting to jump the camshaft, then they would expand to take up the slack, and keep the valves open. The engine stalls. 5 seconds of bleed-off were enough back then to collapse the lifters back down to operating size, but maybe only because the engine was warm, whereas my mechanics were trying to start a dead cold engine.

So my first suggestion is: Try and see if your engine stalls like that at high rpm, i.e. it needs several seconds to recover. This would indicate slow bleed-off! Then change the oil to a lower viscosity, higher quality oil. The lifters might then bleed faster, and the stalling will recover sooner. It's worth a try.


My second suggestion is to run synthetic oils or other cleaning agents (maybe Auto-RX, I'm gonna try it) to reduce oil gunking and remove, gradually, old gunk. If your oil has a tendency to gunk, and if it gunks inside your lifter, then they will definitely be stuck after 300 miles, leading to the exact described symptoms.

And finally, in my understanding the main advantage of hydraulic lifters is that they are self-adjusting. They can expand quickly, and bleed back down slowly. Until they gunk up - then they only expand and no longer auto-adjust in both directions. A really gunked up lifter might also not expand at all, and you'll end up with a rattling valve train.

So in conclusion, this is how a good hydraulic lifter should feel:

- Stiff, but with slow and noticeable bleed-off when it's filled with oil
- If you empty it, the now air-filled lifter should compress easily and freely against its internal spring and snap back immediately
- Once you reinstall the lifter, it will take a few seconds of cranking to fill it with new oil, but usually you don't need to do this manually beforehand - it seems these things fill themselves relatively quickly. Anyway, while the lifters expand and fill, the engine will stutter due to poorly operating valves, but after a minute or two it should run smooth and round. No clicking should be heard, and now the lifters should have eliminated all play and attained the proper length.

Sebastian