Repairing Ticking Lifters in a KA24E
Most SOHC owners complain of lifter tick.. or actually, the lash adjusters not working properly CAUSING a tick, but few know that it CAN be repaired as a DIY project.
I dont know if you all have read up on the subject, but this past few weeks i have read any and all info about hydraulic lash adjusters from Wikipedia, searched Google (read over 300 pages) and searched all the nissan forums out there..
Anyway.. here is an explanation for what a lifter does.. Thanks to Wikipedia..
A hydraulic lifter, also known as a hydraulic tappet or a hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. Conventional means of adjusting valve actuation always require a small clearance to be left between the valve and its rocker or cam follower to allow for thermal expansion and wear, as it is vital that a valve must never be prevented from closing completely; this rapidly burns it away, especially in the case of the exhaust valve. The hydraulic lifter was designed to ensure that the valvetrain always operates with zero clearance, leading to quieter operation and eliminating the need for periodic adjustment of valve clearance.
The hydraulic lifter consists of a hollow expanding piston situated between the camshaft and valve, either operated by a rocker mechanism or, in the case of double overhead camshafts, directly by the camshaft. It is filled with engine oil intermittently from an oil gallery through a small drilling. When the engine valve is closed, the lifter is free to fill with oil, but when the valve is opening and the lifter is being operated on by the camshaft, the oil feed is blocked and the lifter acts just as a solid one would, oil being nearly incompressible.
So, now that we know what it is..
What happens when a lifter gets dirt or air inside of it, gets stuck open, or seizes closed?
NOISE, lots of it..and possible damage since they may not open or close the valves all the way..
The valve lifters need to be bled when putting them together.. The smaller diameter tube has a valve that only opens when it is being pulled out of the other piece..(thats the best way i can explain it)and what you need to do is find a needle, and push some oil in on that valve with a needle to bleed the air out of the lifter itself.. (it will compress as you bleed the air out) this image below is of a different set, but the idea stays the same..
Here is an example of an assembled lifter by the various parts.. The lash adjuster when correctly bled and assembled will look like this, and will barely budge (like .5mm) If it moves up and down then you forgot to bleed it all the way and/or forgot the little plate that goes on top of the lash adjuster itself..
See, I have pics of the good, but how about pics of the bad?.. Here it is.. collapsed AND seized lifters.. look how far IN that lifter is.. and also the part of the lash adjuster that moves up and down to control the gap is seized in, and wont budge..
Oh yes, some picks and a good tiny screwdriver will do wonders to take off the little ring holding the lash adjuster itself.. Carb cleaner is a must.. and be prepared to spend a whole day doing it..BUT the rewards are great.. And silence really IS a virtue..
Here is a picture of all of the adjusters.. (the little PITA clips can be seen below the rocker arms themselves..)
HAVE fun, and enjoy the quiet!