Lifters gone to hard

[darky82]

Hi was in the process of iliminating a low vacuum problem with my 5.0L i have come to the conclusion that my lifters (hyd) have gone rock hard, so when i try adjust my roller rockers down half a turn the valves go down insted of the lifter, any help would be sweet..

[stuntmanmike]

Umm. I'm 100% sure that adjustable rockers should not be used with hydraulic lifters. The primary issue you are experiencing is that you can't measure the required valve lash accurately. Secondly, your hydraulic cam won't be performing too well in the low to mid rpm range where the hydraulic movement in the lifter is usually apparent and varies the valve lift behaviour and essentially the cam lobe reaction. Hydraulic lifters normally leak down as part of their function.
Cam lobes for hydraulic lifters are also a different shape and may not wear well when used in a pseudo solid arrangement.
Adjustable rockers are only suited for solid lifters or solid roller lifters. Here the valve lash can be adjusted to suit the intake valve temperatures and for the exhaust valve temperatures.
You might want to adjust your rockers so that the push rod is seating with a slight "interference" fit between the rocker cup and the lifter cup. This will save your valve train for now as a temporary measure.
I strongly suggest that you either change the rockers to a suitable "hydraulic lifter" friendly type or change out your lifters and pushrods as a minimum. A camshaft change to a "solid lifter" profile is also recommended if you are keen to go down the "solid lifter" path. Good luck and don't go too hard on your engine while it is set up like this for now. Best of luck. Phew...

[VR38]

Ah hummm... the lifters are full of oil and go solid (Hydraulic) to open the valve against the spring pressure.

[VR38]

Oh and adjustable rollers, provided they are adjusted correctly, are more than suitable for hydraulic lifters, they don't care if the lifters are solid or hydraulic...

[stuntmanmike]

Oh and adjustable rollers, provided they are adjusted correctly, are more than suitable for hydraulic lifters, they don't care if the lifters are solid or hydraulic...

You are quite correct and I apologise to you VR38. Correct adjustment is necessary as per your comments. And using an adjustable rocker on hydraulic lifters does work when the geometry between the lifter and the rocker are within spec.

I should have added that I only use adjustable rockers with solid lifters for the valve lash adjustment and with aggressive cam profiles. I keep non-adjustable rockers on engines with hydraulic lifters for low maintenance (ie no need to adjust valve lash as the lash is "zero"). That's just my way...

To explain further:
The hydraulic lifter will take on a set volume of oil with each cam rotation. And adjusting the set screw too far on the roller rocker will push the pushrod down further into the hydraulic lifter causing the cup to lower until the lifter cup bottoms out on the lifter. Going too far with his adjustment will see the valve lift open and not seat fully against the valve seat when the cam lift is zero (before and after the lobe).

At 2000 rpm the lifter is moving slower than at 6000rpm when the lifter is moving up and down approximately 25 times per second (or 1/4 less times than the rpm). This may help illustrate what I'm attempting to describe: ‪hydraulic tappets / hydraulic valves (or hydraulic lifters)‬‏ - YouTube
I also believe in "leak down rates" depending on the design of the hydraulic lifter, rpm and entrained air bubbles in the oil from crankshaft turbulence. I found this to support this statement: http://performancetrends.com/Definitions/Lifters.htm

Again I apologise for not explaining myself correctly in my initial response.
The real issue appears that the hydraulic lifter cup is bottoming out due to incorrect adjustment in what is being described by darky82. I hope that helps and it is always good to hear feedback and more than one opinion in these forums.

[darky82]

Yeh i get that but its like my lifters have gone solid wont go in at all like they should when you adjust them

[VR38]

THEY ARE NOT SUPPOSED TO BE ADJUSTED IN ANY FURTHER THAN 040thou.

[stuntmanmike]

Damn. This is a tough one...
It might be time to pull out a lifter to have a closer look.
I know that it's a PITA to pull apart the engine and that advice from an armchair might not solve what the exact issue is.
Is it occurring with all the valves/lifters or just one or a few?
I hope someone else has experienced this and knows the precise answer. Best of luck with solving your issue.

[darky82]

Its all of them they are all still up.

[darky82]

I just checked the old lifters i took from my engine and you can even push them in with a screw driver on the ground