Clackety clackety clackety clack
 

Hi everyone! SmileWavy

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...

<iframe width="560" height="315" src="//www.youtube.com/embed/BAktMlqWsCc" frameborder="0" allowfullscreen></iframe>

http://forums.pelicanparts.com/uploa...1408435517.jpg

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!

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.

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.

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?

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.

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.


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!

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?

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.

Rocker shaft fell out

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.

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

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

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.

no case split
 

I see a master link on timing chain, no need for this part when case is splithttp://forums.pelicanparts.com/uploa...1408507255.jpg

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

<GROAN>

Will do, and thanks!


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.


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



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.


Please explain.


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

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

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.

Allright since you cant narrow it down by sound, you have to start taking stuff apart, take the upper valve covers off first, you dont have to drain the oil, you will be able to see the rockers, and if they have came loose, etc.

Next you can drain the oil, and remove the lower valve covers, might as well take the sump cover of the bottom as well.

If you havnt found anything yet then go to the chain boxes.

Not tried it myself, but to save draining the oil in order to remove the lower valve covers, can you not jack up one side of the car, wait for oil to drain to the lower side, then remove the high side covers? Just trying to save the guy some time/effort ;)

From what I've read (think it was Waynes book), the shafts also have to be removed in the correct direction by whoever does/did the rebuild, to reduce the likelihood of damaging the housing....I know from when I removed and reinstalled mine, once cleaned-up fully including the bolt threads, they re-install really nicely. If the shop weren't diligent with cleaning and locating them on install, perhaps as Afterburn says, one has worked loose?

There is one thing that it might be.
I had a valve guide come loose in the head once.
It was riding up and down with the valve instead of the valve sliding through it.
The ridge on the guide was slapping against the head and made a really loud clack each time it did.
Not sure how you would see this with an assembled engine...but keep it in mind.
Bob

Not if he doesn't find anything, then he just wasted the time jacking up both sides of his car. It's a gamble either way but if I was doing it, I would just drain the oil and remove the sump cover first, before anything else.

Removing the valve covers is EZ enough...If it is fixable while in car, that is where to look. Other then that, engine is coming out anyway.

Hey, thanks everyone for the help! SmileWavy I have a further update.

Today I got out a couple of long handle socket extensions to use as listening devices and spent a good 15 minutes trying to get closer to the source of the sound with the car idling. This wasn't as loud in my ear as with the screwdriver, but I was also able to narrow down the location to the passenger side of the engine. So disregard what I said earlier about the noise being everywhere. Here is a summary:

Upper right valve cover: loud rhythmic clacking
Upper right valve cover nuts, especially at cylinder nr. 4: loudest most distinct clacking
Lower right valve cover: less loud but still very clear clacking
Left side valve covers: no clack
Timing chain covers: chain-running-on-sprockets noise, no clack
Block underneath near sump plate: mechanical noises but no clack


So I think I know where to go looking and I have been reading up on rocker shafts.

Question: Is it common that the heads need a re-torque in a certain number of miles after a rebuild?
Question 2: Does the AC compressor need to be removed to facilitate getting at the valve cover? Any other tips for making this job easier?
Question 3: I assume I'll need new gaskets. Silicone, or something else?
Question 4: Is there any point in doing a test with the fan belts removed at this point?


And finally, I made a short video of the clatter noise when the engine is shut off. Its the same regardless if the clutch is engaged or not, in gear or not:

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refer to post 26
and no your heads nuts do need to be retorqued (usually) But you are looking for a sound.
i am sure it i valve related
remove covers and inspect

Sounds just like mine did with one collapsed tensioner, I'd pull off the chain covers and take a look

Thanks for the further input. It will be a couple weeks until I have time to take anything apart, so I have time to order gaskets and things. Which brings me to my earlier question. I assume the valve cover gaskets will need to be replaced, should I go silicone? What about the chain boxes, there must be a set of gaskets there too? Sorry for the noob questions-- I'll be ordering both Wayne's and Bruce's books along with the gaskets and anything else you guys recommend I have handy. I live just slightly father away from civilization then Mars, so its important to have parts in hand well before starting any work. :D

You can get by reusing the gaskets for a bit on the upper valve covers, it sounds like you narrowed it down to the # 4 upper. Likely you had a rocker shaft walk out on you.

You may have some damage but you won't know until you take a look.

The orange reusable silicone gaskets take some finesse to work, I used to hate them but have grown to like them, they work great with the right torque and making sure that the surfaces are flat, clean and dry.

Shane,

I am experimenting with the silicone gaskets now. They call out a 4-5 nm torque which is pretty light. Can you tell me what has worked for you ? The nylock nuts themselves take a bit of force to turn them, so do you add a bit to the 4-5 nm to compensate ?

Likewise, I'm now using a set of the silicon gaskets on the valve covers. I used a combination of the recommended torque for the M8's, plus a little bit until I could see the gasket squashing down. Engine's still on the stand, so a perfect opportunity to increase if there's a more proven suggestion (which I'm sure there is!...)

The silicone gaskets have to be clean and dry, the mating surfaces have to be clean and bone dry as well.

Check your valve cover surfaces for flatness, you can sand them lightly on a thick glass surface.

Put the gasket over the valve cover studs on the engine side ensuring it lays completely flat, now gently place the valve cover on, thread all the nuts in just enough so that the gap is closed.

Now turn the nuts in sequence from the center out to about 3 nm, then go over them again to full torque, the gasket should be compressed only slightly, just enough that it is even with or barely squeezing out past the edge of the valve cover. If it is squeezing out more than a thumbnail it is too tight. If you have tightened your gaskets so tight that it has left marks on the surface of the gaskets then they may leak.

So .... tighten to 3nm and then "full torque". What is the full torque specification you are referring to ? Do you compensate for the nylock nuts (which cannot be hand tightened because of the resistance of the plastic seal inside them. Thanks

possible broken valve spring?? Had that with mine.

http://forums.pelicanparts.com/porsche-911-technical-forum/467152-found-broken-parts-engine.html

Engine noise
 

Just a thought, how tight is the fan belt? If it has been over-tightened a bearing in the alternator could have been damaged. You might try taking the fan belt off and starting the engine to see if the noise goes away or stays. At least that would eliminate a possible source/problem.

Thanks for the link! Did yours make similar clackety noises before you changed the springs? Is it possible to see a broken spring without removing them? I see that the PO elected not to change valve springs on the rebuild, so of course they are suspect too. There are a lot of miles on most of my engine parts.

There was increased valve noise, but not as much as I thought there would be. Couldn't really tell if it was broken until I removed the spring.

Others (experts) told me you can feel a softer spring when the cylinder is on TDC (no tension on the spring) and you push on the spring with your hand. I used a screwdriver to get in there. Honestly, I couldn't tell. But then, I'm no expert.

Good luck.

I would think that if it originally was built with nylock nuts, the given torque would be with their resistance included.