<span style="font-family:Times New Roman">Long time no post, guys but I feel compelled to help others.
This is a long post, but I want you guys to follow my thinking and experience because I know I'm not alone with this issue, and I believe it will help. I have a 2000 mirage with the 1.5 liter 12 valve.</span>
For any car suffering from valve lash noise, clicking, whatever and want to do this job themselves, I want to outline what I did to finally make it go away. For years I had the dreaded embarrassing click clack click clack click which came and went, cold or hot. The clicking would go away sometimes if I do a restart, which I attributed to an immediate burst of oil pressure. It would click less when I did a 10w30 oil change and worse when I used 5w30, dino or synthetic. Anyway, this started years ago.
I first cleaned all the valve lashes as per factory service manual and bulletin, using diesel fuel a few years back and it helped nothing. I did motor flush several times, even driving with it in the crankcase for a few miles, tried marvel's mystery oil, tried seafoam in the crankcase as well. I tried that absolute nonsense revving to 3000rpms over 15 seconds thing that's all over the internet about air bleeding the lashes too. I would get some results for a few miles only and then the noise would return. Finally after 2000 miles since my last 5w30 synthetic oil change at 192k miles, when the clacking was at it's peak I decided enough is enough. I put the car on ramps and drained the oil and removed the oil filter.
After it cooled down, I removed the valvecover and slowly took off the valve lashes individually, no special tools at all but kept a magnet handy, and this time removed the rocker arm tubes as well. I kept the rocker tubes and rocker arms intact and set them aside. Nothing seemed bad. I even checked each rocker arm while slowly turning over the engine manually before removal, trying to pinpoint which lashes were at fault but all were nice and firm, no play. I guess they were all full when I shut the car off and didn't have time to lose their pressure. This time I did a couple of modification to the factory service manual and bulletin procedure. I filled three steel bowls with KEROSENE instead of diesel. I threw all the lashes in the first bowl, not caring about keeping them in order. cleaned each lash by pumping the plunger while holding the steel wire in the hole maybe 30-40 pumps and threw it into bowl number 2. did that for each of the 12 lashes. did the same thing in bowl number 2 and finally again in bowl number 3 and left them soaking in the bowl overnight. Each and every lash was incompressible when full.
I'm pretty strong and I tried as hard as I could but they wouldn't compress unless I depressed the internal ball with wire. I did notice that each and every lash had significant side to side play at the plunger. I could move the plunger sideways and also turn the little snap ring that held them in place and hear it click side to side, NOT down. I also measured each lash and got 26mm for each one. I went to the autoparts store and compared with a brand new one. Even the new one had side to side plunger play, though not nearly as much as mine but the new snap ring was immovable.
I thought sheeet, I'll have to get all new lashes and they aren't cheap! I then figured it really isn't that hard to replace lashes, so I'll give it another go with the old ones and see. I went home and carefully slid off the rocker arms from the rocker shaft and made sure to organize them so they are in the right order. two at a time,I'd soak the rocker arms in kerosene, then used carb and choke cleaner with the little red tube and sprayed all holes of all rocker arms. there is a hole from the rocker tube that lines up with the rocker arm that supplies the lash. there is also a very small hole at the top of the rocker arm that allows excess oil to escape. all forced clean with the red tube carb spray both forwards and backwards. you can bend the red tube from the spray to get into the corners and feed holes and watch it come out the other end.. Then onto the rocker tubes, checked for scoring or other defects, and each and every hole was sprayed clean.
I used a needle to make sure the tiny oil holes weren't blocked and sprayed everything twice and lubed it with new oil and reassembled them with the rocker arms in order and set it aside. I did not come across any obvious blockage, all channels appeared clean. I even sprayed down the holes in the engine block that supplied the rocker tubes. they didn't go far before hitting the camshaft, but I did it anyway. while the lashes were soaking overnight an idea popped into mind. I was going to go a different route than the factory at the last fill of the lashes. the bulletin says to depress the internal ball with wire and fill the lash by releasing the plunger. THIS TIME, I depressed and held the plunger down, THEN REMOVED THE WIRE and THEN released the plunger.
The idea being this would force the lash to suck up kerosene using only the side fill hole of the lash. If you think about it, when youare using the wire to depress the steel ball and holding it open, kerosene willfly in and out of that same hole while your filling it. I wanted to chase kerosene into that lash the same way that oil would go, which is from the SIDE hole. So, the wire would be used to depress the internal ball, compress the plunger and hold it, then remove the wire, and THEN release the plunger. this would flush the fill hole of the lash with good ol' kerosene. I did that several times and noticed a significant vibration in the lash while the lash was sucking up kerosene and knew I was onto something.
Then I asked God to bless my work (I am FAR from an ideal Christian, but I like to ask for his blessings when I'm at my wit's end) and put it all together, then filled the crankcase with new synthetic 5w30 (the exact same oil that made the noise worse before) and a new oil filter. I rolled the car downhill in gear with engine off slowly to build oil pressure, I didn't want an immediate startup with bone dry rocker tubes and rocker arms. Guess what my friends? To my dismay the clacking was still there immediately after startup. I was about to throw a child-like fit, then decided to drive around and see if perhaps the kerosene was seeping out and perhaps the air trapped in the rocker tubes and rocker arms needed to get bled out. well, within a mile, I kid you not, the noise disappeared. No nonsense revving, no spirited driving at all, and now 20 miles later, the noise is gone.
I know it's fixed. I couldn't travel any length of road without it clacking for months now. this will help anyone with valve lash noise. I believe the key is to REMOVE THE WIRE holding the internal ball and allowing the lash to fill with it's side fill hole like 10 times each instead of keeping the wire in there and pumping like the bulletin states. As far as the guys who replaced lashes and still had the noise, I'd recommend taking off the rocker arms and rocker tubes and cleaning them out as well, very important. If that doesn't work, then you must have low oil pressure or are aerating the oil somehow, like with low or high oil level and/or a broken pickup tube which is sucking in air in your crankcase. But before you go hunting for an oil port to hook up a oil pressure gauge or taking off your oil pan to hunt for a broken tube, try my method. I hope this helps.