All credit for This article goes to Silver_Bullit over on the ProbeTalk.com forum
A Hydraulic Lash Adjuster or better known as an HLA is nothing more than an ordinary hydraulic lifter. It (on the Mazda KL series engines and the I4 in the base probe) sits directly between the camshaft and the valve stem. As in an old conventional V8 that has pushrods, the HLA simply keeps the space between the camshaft and the valve stem filled 100%. The conventional V8 uses a couple more moving parts, such as pushrods and rockerarms, but the principle/basic function is the same.
Ok, now that you know what an HLA is and what it does lemme explain why they tick.
The HLA’s tick due to crud/gunk/slim buildup in the oil ports that go into the HLA and in the oil ports on the inside of the HLA. Also the HLA tick is caused but crud buildup on and around hte check ball that is located inside the HLA. This check ball simply stops oil from flowing back out of the HLA as the cam turns and puts enough pressure on the HLA for it to open the valve. If the oil gets pushed back out of the HLA because of the check ball not working properly then the next time the camshaft turns the HLA will make a ticking sound. This is the result of the camshaft having space between the lobe of the cam and the upper surface of the HLA, and as the cam turns it comes back in contact/hits the HLA. As you can imagine, to parts of and engine hitting against one another for an extended amount of time is not a good thing. This is one of the reasons why a light weigh oil must be used 10w-30 or 5w-30. Also, a synthetic oil is preferred, as it has a lot fewer contamination’s than regular oil. When the HLA’s start to tick you can easily hear them with the engine running at idle and more easily than that they can be heard when the engine is cold and first started.
DISASSEMBLY:
1)The basic HLA pusher/lifter housing.
2) Pull the HLA out of the lifter housing. As seen here using a pair of robogrip pliers.
3) One little clip ring holds the HLA into its housing, seen here.
4) Pull the two (2) halves of the HLA apart.
5) Now you have the small half and large half of the HLA, along with the larger spring.
6)Pull the ball keeper off of the end of the small half of the HLA.
7) The result of #6, the spring in the background is the larger spring. There is also a very small spring that presses against the ball; it is located inside of the keeper, as seen in this pic…
8)The smaller half of the HLA and the oil ball. The HLA is now completely disassembled.
REASSEMBLY:
Do not put any oil in the HLA while it is apart, let them soak in a can of oil overnight and fully compress them the next day before installation.
Fully dismantled…
1) Put the ball into the shallow end of the smaller of the two halves of the HLA.
2) Put the VERY small spring inside of the keeper (kind of blurry, sorry).
3) Put the “keeper” with the spring inside of it onto the end of the smaller half of the HLA, make sure that the spring is against the ball and that it is pushed all the way into place.
4) Now place the larger spring into the end of the larger half of the HLA, make sure that it is straight.
5) Assemble the two halves of the HLA so that the large spring and “keeper” are touching one another. Also, make sure that the deep end of the small 1/2 of the HLA is facing out/up.
6) Use a small needle or pin to push the ball down so that the internal pressure can be relieved so that the HLA can be compressed fully, compress it fully and pull the pin/needle out.
7) Reassemble the HLA and “pusher”, “lifter”… Put the end of the HLA that has the opening in it into the pusher/lifter first.
