rotaxmatt

Hi everyone - this is a great forum and my first post.

I have a 98 C4S with 64,000 miles which I use as a daily driver. I have noticed an increase in noise from the engine which sounds like it is coming from the rocker cover areas. Having looked on the forum it could be collapsed lifters.

It is a clicking/tapping noise which is pronounced at idle.

What do people think - I have posted a link to a video so you can hear for yourselves?

Could it be anything else?


https://www.dropbox.com/s/t862nqv0hm...93%20noise.mov

e3photo

Hard to tell,but I had a collapsed lifter once that sounded like that. Try to narrow down which valve cover it is coming from.


Emerald

rotaxmatt

I have a similar sound from both sides, the second side in the video is worse. Would a good independent be able to diagnose by sound alone or would it be a bit of an investigation? I assume it is best to change all of the lifters if I have a problem on both sides?

e3photo

A good independent should be able to diagnose the cause and location. It may turn out to be something entirely different. You haven't given much to go on. Has it come on gradually,or all of a sudden. Any gauges seem off. Have you changed oil recently,say to a different type or weight. There are too many variables for an armchair diagnosis. Have an indy look at it,and you can always report back for feedback on the diagnosis.

Good luck.

Emerald

CaptainGSR

I collapsed a lifter on the driver's side once. I could not tell whether it was coming from the top or the bottom of the engine, but it was obviously coming from the left side.
Mine collapsed all of the sudden on a very hot day, with the engine temperature at 9 o'clock. The clapping suddenly came out of nowhere.

As a "while I was in there scenario," I went ahead and replaced all six on that side, together with the upper and lower valve cover gaskets, and bolts (easy to strip, so put new ones while you are in there.)
My engine runs smooth. I have not had an issue in 4 years. The passenger's side lifters have the full 108000 miles and they are still fine. No sense in replacing parts that are not broken in my book.

If both sides are messed up, upper or lower, then I would replace all twelve. The engine tins and mufflers have to come out most likely anyways, so might as well do both the uppers and the lowers, plus valve cover gaskets, and these stupid allen bolts (FYI: pep boys sells the very same bolts!) It also gives you great access to the spark plugs/wires.

I would get a cheap stethoscope at harbor freight. Lifters or not, at least you will be able to pin point the source of that clapping, by yourself, and in no time!
I watched your video a good ten times. I really can't tell anything for sure by listening to your driver's side, but on your passenger's side it sounds like lifter(s) to me.

Replacing some collapsed lifters, is a small price to pay every fifteen or twenty years, for not having to bother with doing regular valve adjustments in a street car! :-)

I hope this helps. Please let us know what you ultimately find in there.

BTW: are you running 0w40 oil in that car? I switched to 15w50 a few years ago and it significantly quieted down my valve train.

rotaxmatt

Thanks for the detailed reply. That helped a lot. I have used 15w50 since I owned it (2 years). I will post back what I find and post a before and after video.

rotaxmatt

I sent the video to my local (50 miles away) mechanic and he thought it was lifter noise and so I booked the car in. I arrived and from the sound of the engine on arrival, he was confident it was the lifters and so I had all 12 changed. I have included a link to the old ones below. The seals were all brittle and cracked and so they probably needed all changing anyway. The worst of the noise has gone, but I am not convinced the whole problem is solved.

Old lifter picture
https://www.dropbox.com/s/0iyt6njydg...%20lifters.jpg

My main concern is that the ticking noise is still there although greatly reduced and I can now hear top-end noise at between 2,500 - 3,500 rpm when driving on a balanced throttle. I have included links to the before and after videos. Strangely, the exhaust note has changed dramatically which was the first thing my wife noticed when I got home?

I discussed the mechanical noise with my mechanic and he said it was not there on his test drive, but he never really cruised in it and to drive it 200 miles and then we can discuss. He confirmed he checked the rocker arms and cams and they were all good.

What do you think? Is the engine noise at idle normal compared to your cars or do you think I still have more work to do?
AFTER
https://www.dropbox.com/s/0c6197p1q2...r%20change.MOV

BEFORE
https://www.dropbox.com/s/t862nqv0hm...93%20noise.mov

CaptainGSR

I am curious to see what experienced mechanics have to say about this.
Your engine sounds fine to my untrained hear :-)

BTW: just curious, do you have a light weight flywheel on that car, or is it the stock dual mass?

rotaxmatt

It is the standard flywheel as far as I know.

rotaxmatt

I should add that the mechanic put in 3 different sizes of lifter. Is that right? I had not read about that and thought it should be a single size for a specific car.

Carrera Cup

Hi everyone,

Firstly, my apologies for being so infrequent a visitor. I find myself coming onto your brilliant forum less and less due to other time comittments (a poor exceuse I know). However, I feel that I must make a contibution to this thread as my own experience seems to mirror pretty closely that of the OP. My car sounded EXACTLY as that of the OP (I now wish that I had taken some video at the time so that I could do a before and after comparison)

This is a copy of a post that I made in 2012 on the the 911UK forum....

"My car – a pretty high mileage example – had intermittent ticky issues for some time. On the off chance that it is of benefit, I can attempt to summarise my experience and thoughts on this....
1) A change of lifters (both sides – what the heck) had a beneficial effect without clearing up the problem completely.
2) The engine, still pulling like a train, had little or no evidence of valve guide (or indeed valve) issues. Cylinder compression was good, oil consumption well within spec with no smoke on start up.
3) I changed the oil to a thinner oil (5w30) as an interim step and this helped quite considerably after a few miles. I put this down to the fact that the oilways supplying the lifters, which of course operate under oil pressure, are pretty narrow and are therefore prone to clogging. This in turn can have a starvation effect and influences the extent to which the lifters can operate to the correct (ie zero) clearances under load. I have also been told that the passenger side is can be particularly prone to this starvation problem to a greater or lesser extent, though why this is the case remains unclear. The thinner oil definitely helped to combat the issue, especially when the engine was COLD.
4) A second oil change to a slightly heavier grade (5w40) was then done. It is also worth noting that the 993 has a second, smaller, oil filter which I understand serves primarily to purify the oil entering the cylinder head oil passages. A change of this filter together with any change in the oil is to be recommended in my view.

I still have a little top end noise with the car which, as per other posters’ comments, is by no means unusual. This is not in any way intrusive and, in any event, is only noticeable on free revving (not under load). To the extent that it is (barely) audible, the noise is mostly present NOT when the engine is cold but rather when WARM, at which point the metals have expanded. This would not typically point to lifters but rather valve guide wear.

993 valve guides, which I believe are manufactured from a Phosphorous Bronze alloy, are quite soft and prone to wear. This is at first glance an achilles heel for the car and is widely regarded as such. However, on further reflection this can been seen actually as a rather smart engineering move by the guys in Stuttgart. After all, it is far better for the guides to wear rather than the valves themselves – for which the consequences of a failure could be literally catastrophic for the engine. Far better for the wear to occur gradually – giving us time to plan for a potential top end rebuild – rather than have critical components letting go suddenly and without warning with all the pain that this would bring.

For me, a top end rebuild will definitely be on the cards at some time in the future. In the meantime, I am very happy to cherish the car as it is. A little bit of top end noise really is very much part of the character of these fabulous cars."

Since I wrote this a bit more than 18 months ago, the car has had a further oil change. I have also used a little Wynns Hydraulic lifter cleaner in with the oil about 100 miles prior to the change. I can report that the noise is now pretty much completely GONE. For me, the regime of oil changes (I would almost call it oil management) has paid real dividends. None of this alters the fact that that the engine is a higher mileage example so will almost certainly need attention at some point going forward.

PS: for good order, I have attached a video of my car being remapped about a month ago by Wayne Schofield on 9M's dyno. Not much help I'm afraid as you would never pick up lifter tapping above the combined noise of the Dyno road and the Fister IIIs that are fitted to the car (thanks for that Darin!!)

Steve Weiner-Rennsport Systems

Porsche made 3 sizes; standard and two oversize lengths, to accommodate varying seat depths after doing a valve job.

For engines with stock valves that have never had a valve job, the standard lifters should be used.

I've never installed different lengths in the same engine,.......

rotaxmatt

Hi Carrera Cup - I had come across your previous post before. Thanks for the follow up. I have done about 150 miles on the engine since the lifters were changed and it is not better. Interestingly, on a cold start the driver's side is pretty silent and becomes more noisy when warm, but I think it is OK. The passenger side is pretty bad at start-up and settles down to an annoying ticking which is still very grating above 2000rpm until it is drowned out by engine noise at 4000+. It has just had its second oil change in 1000 miles. First one was done at Darin's shop - he is a really nice guy to meet in person. I had the car lowered on PSS10's there and it was a really nice job. Anyway, I will be videoing the cold start, current warm condition and sending to my mechanic.

rotaxmatt

Steve - thank you for your response. I take it you would recommend getting the right lifters installed? Could longer lifters be causing the problem?

Steve Weiner-Rennsport Systems

Using longer lifters without compensating by machining the seats and valve stem tips basically bottoms the lifter, leaving insufficient clearance.

I would be checking them to ensure there is proper valve clearance as this can be the source of your noise.