Top-Gun

I just finished up replacing the exhaust lifters on my 95 C2 (65K miles). I decided to replace them after hearing a ticking from the drivers side exhaust bank that was especially prominent with the motor warm.

I didn't find any collapsed but the O-rings had more or less desintegrated on all of them. I carefully cleaned each rocker and shaft with warm soapy water and blew out all oil passages. I soaked the new lifters in fresh oil (standard length), and coated the rockers/shafts with oil and buttoned it all back up with the proper torques.

I pulled the DME relay and cranked for a bit to get some oil pressure, then fired the car up. I had a pretty nasty "clack clack clack" from both exhaust banks, however after 5 mins or so and a few quck revs the passenger side quieted down.

The drivers side however is still clacking away. I let the car run for 20 minutes or so and blipped the throttle a few times up to 4-5K RPM but it won't quiet down on the drivers side.

Just trying to figure out what to do, I've read that sometimes it takes time for new lifters to pump up but I would think they've had plenty of time/oil pressure? I didn't see anything alarming when I had it apart, the bottom sides of the rocker shafts had a polished silver finish (i.e. not gold like the rest) but no scratches and they all looked identical wear wise. Cams looked fine as well.

I'm worried I either got a bad lifter, the wrong length, or the noise before wasn't from the lifters and something else is causing it. Any input would be greatly appreciated.

jan the man

If all you did was lifters, drive it, mine did the same thing and untill i drove it for 10 minutes the noise didnt go away. I replaced all 12 even after that one was faulty after i would idle for a while one would start clacking so i replaced that one again now all good. funny it was the lower front drivers isde as well.

Mike J

I did a set a while back, they did pressurize ok, but then one of them failed in less than a week - and I have heard of them being DOA. It almost sounds your example, since your driver's side has never quieted up since your replaced them.

Does it sound like a single lifter or all of them?

Its pretty hard to screw this up, the lifter shafts are keyed, and all you did was replace the lifter itself.

The problem is, even if you tear it down again, it's hard to tell visually if one has failed, and which one is it. One or two of the new ones were DOA, we figured out where it was as best as we could using a automobile stethoscope, and replaced both of them, since I could not hear which one specifically had failed. Both of them looked fine when pulled out, but after replacing both of them, the noise went away. I tossed both out, although its likely one was still good.

So, my recommendation is try to localize which cylinder/valve is making the noise, run it a bit more, and if the noise persists, replace again the ones you think are noisy.

Cheers,

Mike

Top-Gun

Thanks for the replies, I did attempt to localize the offending lifter with the "screw driver to the ear" technique but to me everything sounds the same regardless of where I put it. Theres just an obvious difference with your head in each wheel well, passenger side is quiet and the drivers side sounds terrible.

I'll take it for a drive and hope it quiets down, if not I guess I'll do all three on that side again. I suppose Porsche won't take back parts that have been used? Kind of a bummer since they're not exactly inexpensive components.

Just a thought, if I were to pull the valve cover and check the play on each rocker would the one that failed to pump up have more movement than the ones that have?

Also is there anything I can do to confirm I have the correct length lifters? The car is new to me and although I don't have a record of any top-end work its not out of the question.

Thanks.

GwynnieMae

I'm having the exact same problem and on the same side too. I think I narrowed down the offending lifter with the stethoscope. The problem I had using the stethoscope, everything sounded the same. I left one ear off to match the ticking heard with the other ear. I'll try to report back when I change it. Probably a month from now when I change the oil. I hope everything works out for you.

pp000830

What about the intake valve lifters? Did you replace them as well?
If not it seems that may be the source of your noise. Also the rockers are numbered to match their positions in the engine. Did you put them back in the same locations?

Mike J

The rockers are numbered? I have not seen that - I agree that you need to put the same rocker in the same position because it has bedded with the camshaft, but I was not aware they are marked. Where are those markings?

cheers,

Mike

bobt993

Rockers are not numbered. On a rebuilt engine a builder may have marked them to go back with a set of original cams.

Mike J

Know that. Wanted to see where he saw numbering...

Top-Gun

I did one assembly at a time and made sure the rocker shaft and rocker went back where they came from.

bobt993

Mike, I was certain you already knew this, but wanted to clarify to other contributors.