Clackety clackety clackety clack

[evan9eleven]

Hi everyone!

My SC motor was rebuilt 4K miles ago by a very well respected shop (one of the best in Norway they say) before I owned the car, and the same shop did my PPI. In the PPI they mentioned hearing some engine clatter but didn't specify. I asked and they speculated it might be a chain tensioner, and that the car wasn't fully warmed up when they listened to it. I thought it was odd that a fresh rebuild would be making clackety noises (thats a scientific term btw) but well, it does. Nonetheless I decided not to stress about it, since it was newly rebuilt. The noise is really not that loud and the car goes like a top, but given that this is my first aircooled P-car I though posting a video might be a good idea. In the video the engine is fully warmed up, and the oil cap is removed until the end of the video-- the noises are easier to hear with the slow no-oil-cap idle. You'll need good speakers or headphones to hear it, and even then I'm not sure the sound comes through. The engine had 156K miles on it when it was rebuilt, below you will find the parts list, most of which is fortunately in English. Based on the list can someone tell me if this was a split-case rebuild or just the top end?

Of course its not as though I can do much about it... my current plan is to drive it for a couple years and then rebuild again with EFI, but maybe you guys have some comments? TIA...

[Heinz911]

I have had a bad experience with clackety noises, but that was far louder than this. There are so many possible sources that it is really hard to judge based on a video. But I hear the sound and it is not normal. Best you can do is using an engine stethoscope to pin down where the noise is coming from and then try to find the root cause. What also helps is to determine the frequency. As the crank rpm is double that of the cams and if it is an exhaust leak it is probably once in 2 crank rotations. Good luck!

[Lapkritis]

When was the last valve adjustment?

[evan9eleven]

Originally Posted by Lapkritis

When was the last valve adjustment?

Without knowing for sure, I'd guess when it was rebuilt. Looking back at the invoice from the PO that was two years ago, and as previously mentioned the car has gone only 4K miles since then-- assuming the mileage was correct on the invoices. I'll have to look at some other documentation when I get home tonight too, I seem to recall that the PO telling me the car had done 6K miles since the rebuild, though he may not have remembered correctly. If he was right its gone 8K miles since being rebuilt including the mileage I've added to the car since March this year.

[RedCoupe]

Somebody who has time to check all the part numbers on the invoice may be able to give confirmation of this, but because I didn't see main bearings or intermediate shaft bearings on the invoice, I believe that the work was just a top-end overhaul. I would start by pulling valve covers and checking valve clearances. If it still makes the noise after that, I would get the stethoscope out.

[Lapkritis]

I just watched the video. I think the noise is coming through the case not the heads based upon the tone and frequency. Does the noise go away when you step on the clutch?

[RedCoupe]

Another thing to check is whether the sound increases or decreases when you speed the engine up and drop it back to idle. Rod and piston pin knocks usually change noticeably when you do that. I didn't hear that in the video, but then again I'm not there.

[evan9eleven]

Originally Posted by Lapkritis

I just watched the video. I think the noise is coming through the case not the heads based upon the tone and frequency. Does the noise go away when you step on the clutch?

Sounds like its deep in the case somewhere to me as well, I really hear it well when I get my ear behind the fan housing and deep into the engine bay. No change with the clutch depressed.

Originally Posted by RedCoupe

Another thing to check is whether the sound increases or decreases when you speed the engine up and drop it back to idle. Rod and piston pin knocks usually change noticeably when you do that. I didn't hear that in the video, but then again I'm not there.

Its a bit hard to tell with increased revs, as anything over idle induces so much other noise (fan whine and exhaust especially.) So its as though the clatter is worst at idle, but that may be my imagination. The noise does speed up according to revs to the extent I can hear it, so yes it changes noticeably.

Another thing-- I just checked the above with a cold engine, which is the first time I've put my head in the engine bay without the car being fully warm. The clack is more like a thunk, more random as well where as the clacking is consistent. None of this is a good thing well is it. I have to agree with RedCoupe that there don't seem to be any crank bearings on the invoice so in all likelihood this was just a top end refresh and the bottom end has 160K miles of hot weather use under it, at the hands of 14 owners before me. Car runs great though!

[evan9eleven]

Double checked, rebuild was 4K miles ago as first thought. If something bad was lurking in the bottom end, how obvious would this be to an expert builder when he had the top end apart?

[snbush67]

Could be chain tensioner noise, broken chain ramp floating around.

Could be a number of things.

Narrow the location down by using a stethoscope or even a long screwdriver as a stethoscope, place the blade of the screwdriver at suspect locations and then place your ear against the plastic handle, you will be amazed at how this works.

Likely locations are the upper and lower valve covers, the chain housings, etc.

Does your engine have a sump plate? You can drain the oil and look for pieces of a broken chain guide.

The next step is to remove the valve covers and check the valves and rockers. If you don't find anything there than a partial drop will give you access to remove the chain covers to check the chain ramps and tensioners.

[afterburn 549]

Rocker shaft fell out

[evan9eleven]

New chains and guide ramps with the rebuild (see invoice above) so I sure hope these haven't gone to pieces already! I'll have to get into the valve covers and rockers this fall then, and drop the sump plate when I change the oil before winter hibernation.

[sandgroper]

I wouldn't drive it till fixed, sounds like my old turbo diesel

[simsalabim]

When/if you remove those valve covers, check the torque on the head studs. After mine was rebuilt, they loosened up enough (after 2 thousand miles) so that I had a noticeable clack-clack coming from the head/case interface. Sometimes, a re-torque is needed. They are staying tight now and the clack is gone.

Good luck

[snbush67]

Originally Posted by evan9eleven

New chains and guide ramps with the rebuild (see invoice above) so I sure hope these haven't gone to pieces already! I'll have to get into the valve covers and rockers this fall then, and drop the sump plate when I change the oil before winter hibernation.

New guides and chain ramps can come apart, and sometimes they don't get installed correctly.

As mentioned, you should not drive the car, potentially you can cause a lot of damage to the motor.

[carrerarsr65]

I see a master link on timing chain, no need for this part when case is split

[jsoderbe]

Hi from a neighbor in Sweden!

Just one thought; wouldn't a bearing problem be followed by low oil pressure? In my experience, worn bearings mean the hot idle oil pressure is really low.

So do you have any oil pressure problems?


Regards,

Johan

[evan9eleven]

Originally Posted by simsalabim

When/if you remove those valve covers, check the torque on the head studs.-- Good luck

Will do, and thanks!

Originally Posted by snbush67

New guides and chain ramps can come apart, and sometimes they don't get installed correctly. As mentioned, you should not drive the car, potentially you can cause a lot of damage to the motor.

This is the biggest groaner of all is that I bought this car figuring the fresh rebuild would buy me some time to enjoy and work on the rest of the car first. And its probably been making this noise for thousands of miles already. I'll get out the long screwdriver to see if I can find the source of the noise.

Originally Posted by carrerarsr65

I see a master link on timing chain, no need for this part when case is split

Good catch, that and lack of main and IMS bearings on the invoice confirms it was only the top end that got rebuilt.

Originally Posted by jsoderbe

Hi from a neighbor in Sweden!

Just one thought; wouldn't a bearing problem be followed by low oil pressure? In my experience, worn bearings mean the hot idle oil pressure is really low.

So do you have any oil pressure problems?


Regards,

Johan

Hi Neighbor! If we are to trust the pressure gauge on the dash, then oil pressure hot is just fine. About 1.5 bar at idle, climbing along with revs.

Originally Posted by afterburn 549

Rocker shaft fell out

Please explain.

Originally Posted by sandgroper

I wouldn't drive it till fixed, sounds like my old turbo diesel

So much for my first-ever Porsche Club drive I just signed up for!

[afterburn 549]

The rockers shaft is held by pinch bolt arrangement .

Lots of times not installed correctly and or not enough torq on pinch bolts . The can back out and flop all over the place

[evan9eleven]

A little update. I spent some time with a screwdriver on various engine parts and to my ear. The noise is damn loud in the ear when doing this, and sounds like "kak kak kak kak kak kak kak kak kak..." The frequency at idle (around 800 rpm this time) was just about four "kak" noises per second and perfectly even. Speeds up evenly with revs. Does this tell us anything?

The noise is equally loud no matter where I put the screwdriver-- intake plenum, timing chain covers on both sides, top of the AC compressor... yeah, everywhere. Haven't tried on valve covers though.

And finally, another possibly important detail, when shutting off the engine there is a pronounced mechanical clatter, same clackety-clacketey sort of noise. This with the tranny in neutral and clutch engaged, I haven't tried it while in gear/clutch out. I'll get video of this scenario tomorrow.