Lifter change didn't work, must be oiling problem, need brainstorming. *video*
 

Pretty much at my wits end with this S. I put in a bunch of new lifters around the area where I heard the noise previously. I know I changed the lifter that was making the "clacking". Car sat for a few months, I researched everything and learned how to take out the cams and do the whole procedure. Considering I got this car when I turned 17, and didn't know how to change a tire, now 23 and completely removed the cams, got it back together and had it run, I can't say its a waste.

Initially it seemed like my problems were gone. The car fired right up, idled nicely, no lifter noise. Got the car up to operating temperature, still no lifter noise, took it around the survey, still no lifter noise. Boy was I excited. I fixed it! So I called the insurance and got it back on the road. Drove really nice for a day or two, nice and hot, no lifter noise.

Then all of a sudden, I fired it up, took it for a drive, and THE EXACT NOISE CAME BACK! I know its lifter noise and not a rod or injector, it is a distinctive clack.

I thought I had the problem figured out, but I guess I was wrong. It's apparent that this engine has to come out.

Oil pressure is normal, tried all kinds of different weights, settled at 20w50, still noise. It seems to be coming from a particular area on the cylinder head. I have had some damage in the past, but it was all repaired by a reputable machine shop and the previous damage is not causing the issue. From the top end anyway, the damage may be causing the problem from down below. Which leads me to my next theory...

Could I have an oiling problem that is only affecting a small part of the cylinder head? I have read that on the 968's, if there is a slightly crack in the pickup tube, the variocam tensioner and/or lifters will make noise. Could my pickup tube either be blocked with material, or cracked, and it is causing a slight loss of pressure in a particular section of the head without disturbing the pressure sensor enough? i.e. still reading normal bar on the gauge? I was thinking that since I had the car sitting for a couple months, be jacked shifted and disturbed, maybe the material that was on the tube fell off, then after driving it for a bit, it sucked it up again and it is stuck to the tube causing lifter noise. Could the oil cooler be plugged and cause this issue without reading low oil pressure?

Car is parked, and I'm going to remove the engine at some point in the next few months. Just want to get some idea's as to what could be causing my problems.

What condition were the chain and tensioner pads in? Were the teeth on the cams worn at all? The little j-tube from the cylinder to the chain tensioner was known to develope cracks and leak, which reduces oil pressure that the tensioner gets and thus reduces chain tension. Guess what I'm saying it the noise could be the timing chain slapping around.
Where exactly did you isolate the noise to?
I doubt a crack in your oil pickup is going to cause air to enter the oil system and go straight to a couple particular lifters. You'd notice a drop in oil pressure too.
It may be something you just live with...

How many lifters did you actually fit?, as it could be any one of the lifters that you didn't change out making the noise.

Even new ones tend to loose oil and clack on start-up, however they usually quieten down after a few miles. Perhaps you need to flush the oil system to clean out any 'crud' that might be in the oil feed bores to the lifters?

Could be a broken spring.
Had a customer with a broken valve spring and it made a horrible racket.

I have 2001 S and have the same problem. We used a stethoscope to isolate the noise. Was sure it was the drivers side lifters. I had all 12 replaced and guess what. The noise came back. Don't have another 2500 to do the passenger side and not even sure it would fix the problem. As long as it isn't causing any damage I guess you learn to live with it.

Called my mechanic. He wants to have a listen to it. Will bring it to him next week. This may help with diagnosis, but considering what I am capable of, I dont want to pay for labor that I can do.

The idea of a weak valve spring makes a bit of sense. They were all inspected by Lindsey racing about 15k miles ago, but when I damaged a lobe and lifter it may of weakened a spring. The aggressive cam also will strain them more, but Lindsey said the increase lift not necessitate a stronger spring.

So, if I do have a weak valve spring, how can I go about testing or measuring the spring and its tension, individually, without removing the head from the car?

I really would rather not take the head off. I just put it back on. But I can get the cams and lifters out easy.

Any suggestions?? The noise is too severe to ignore, I'll shatter a lifter and wreck the lobe if I leave it.

Rhett, I fit 6 new lifters. I know I didn't miss the one making the noise. Also none of the lifters I removed were soft. I changed them based on lifter noise AFTER the engine has gotten hot. I was thinking leakdown inside the lifter bore causing it to bleed out when temperatures increased.

I didn't have the noise for a few days of hard driving after re assembly. Is it possible that because the cams were removed for a month, without the tension on the spring, it regained some of its tension and stayed quiet for a few days. Then, after a few days of having the pressure of the cams back on the spring, it resumed its weakened position and caused noise???

Not weak, a physically broken spring. Pull the cover off and look for broken sharp edges where they shouldn't be

Will do. Thanks. Possibilities of oil starvation? Clogged oil cooler or pick up? My oil pressure is perfect. But maybe enough to starve a galley? Head was cleaned thoroughly on last failure. Any remaining material in oiling system will get stuck in filter and not small galleys in head, I think.

Pulled cover. Springs look and feel good. Lifters look good, show signs of rotating in bore. All hard. All bolts snug.

Aside from testing the springs for tension, any other ideas? This is not lifter noise at cold start. It is after it has been driven.

Stuck lifter due to a few too many starts not reaching operating temp? I'm really just looking for opinions and ideas.

Does the noise only happen at idle?

Not only idle, but most prevelent. Also noisy at low rpm. 1k to 2200. When engine is warm only. Does not happen on start up.

My believe is that the cause of the noise is that the lifters do not get enough oil to pump up. It is particular so at idle. As you have changed the lifters probably the lifters are not the cause. The likely cause is that not enough oil is getting to the lifters which makes them noisy. Also the lifters gets oil in when the cam lob is on its way up and looses oil when the cam lop is pressing on the lifter. So a possible scenario is that ware in the head will cause the lifter boar to increase thus upsetting the balance of the oil circulation though the lifter and causing the noise. The balance is particular upset at low rpm which is possible.

The solution will be to go for oversize lifters that reduce the clearance between the bore and the lifter. However, I am not aware of such lifters. Another alternative will be to go for solid lifters. This will be fine I believe but very expensive.

Also is possible this type of noise is not actually lifter noise at all. It may be valve guide ware which can be rectified by an head overhaul.

Hi Makis,

The head was overhauled and new valve guides installed. As well as all springs tested. I had a lifter failure which ruined a cam lobe and scored the journal. This head was than disassembled, cleaned, inspected, and re-installed last winter, with some minor honing to relive the high spots in the scoring. I drove the car frequently throughout the summer of last year putting about 4k on the new lifters and it did not make a sound. All of a sudden this year, the lifter noise developed only when the oil was hot. I tried a heavier oil, did not solve the problem. So I changed the lifter, and the noise did disappear for 2 days of hard driving. Is it possible I got a bad new lifter???

This may not help but on my 86 NA I had a very loud lifter noise after replacing the headgasket. What I did was replace 1qt of oil with marvel mystery oil and drove it around for maybe 10 minutes. As I was driving all of a sudden the tick went away. I then immediately changed the oil.

This may be the issue. Although it does not explain why the noise returned all of a sudden.
When you hone the bore you actually increase the clearance between the liffter and the the cylinder in the head that holds the lifter in place. The oil gets pushed in from the side of the lifter where it enters the lifter. It relies on the pressure caused by the clearance to allow oil to enter the lifter. The pressure drops however if the clearance is too much causing the lifter not to get enough oil and thus become noisy.

Hi Makis,

The honing was actually on the camshaft journal and not the lifter bore. They were never honed at all, so the tolerances should be the same as factory, aside from wear.

If I at some point had material score the lifter bore, could that cause binding severe enough to cause lifter noise? From the appearance of the lifters they appear to be rotating.

***I've uploaded a video. The quality is a little bit weak. My phone's microphone seemed to change tone and kind of creates a bathroom / tube type effect. But it clearly shows the sound and how it reacts to changes in RPM***

This noise was gone for a few days. It spontaneously returned. And is only present when the engine is hot. No noise on cold start.

Again, I just popped off the valve cover, and no lifter was abnormally soft. I could not depress any of them using the end of a wood dowel pressing against the lifter.
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If the lifter bore becomes to large due to ware then oil pressure in the bore will decrease. As a result the lifters are starved from oil and become noisy. This also is more true when the engine is hot (oil is hot and thin) and the presure as a result drops more then cold oil, making the lifters noisy. So in your case it maybe this. How many miles is the engine?

About 110k miles. With one catastrophic failure resulting in material working its way through the cylinder head.

Keep in mind after this failure, and I had everything rebuilt, the noise was not present for at least 5k miles. Nor was it present for a few days after I installed new lifters.

110K miles is not too much so engine should be quite. However, due to the failure you may have more ware in the lifter bore then normal. If the noisy lifter is where the cam lob failed then this is quite possible. You could replace the noisy lifter with a solid lifter and leave the others in place. This may work.

Makis,

That is worth looking into. If someone offers that as an option. What do you think the chances are of one of the 6 lifters I installed as being a dud?

Like I said, I got a few days driving out of it with no noise, so I really thought I had it fixed.