What's this noise? Newly rebuilt 930 engine.

[H/O Driver]

I did remove all plugs and turned engine by hand. All smooth no indications of problems, no noises, chains didn’t flex the tension eta, etc.
All plugs black and somewhat sooty. Kind of expected it since the AFR’s for this turbo engine is a little richer than what I’m used too with N/A American V8’s. Not wet, damaged,-just black.
Spun the alternator, it’s smooth with no apparent problem.
Plan on sticking the bore-scope into the no. 6 spark plug hole tomorrow.

[dannobee]

Is it louder near the bellhousing? Any chance that the flywheel or clutch is loose? Is it the correct clutch for your trans? It doesn't have that rhythmic, consistent sound of a rod/piston/main bearing noise. It seems more random.

[cmcfaul]

sounds to me its on the right side valve trane. Spark plug wires routed correctly? timing correct? Cam timing correct? getting oil? valves adjusted correctly? is there air flow out from the oil filler indicating blowby?

really has to be one of these things.

[cmcfaul]

You said it ran fine for 45 miles. Did you over rev it? Turbo wastegate working properly (did not over boost it). has the airfileter on? Running the right gas?

Chris

[H/O Driver]

Pulled the engine/tranny rest of way out.

FLYWHEEL WAS LOOSE!!!

Each of the six bolts were loose. I would have bet anyone a good chunk of money that I lock-tited them, but forensics say otherwise.

All bolts and holes look good and not "wallered" out.

Now I have to chase the leakdown on the No. 6 exhaust valve. I couldn't see anything with the bore-scope. It was too big to look at anything except straight in the spark plug hole. First thing is to remove rocker and then see if I can get the valve springs off for inspection with the head on. At this point, I'm hoping for a broken/cracked spring that is not pulling the valve up; however I'm not very hopeful. I kind of think that the 100 psi air I used for the leak down test would have seated the valve. Going back out later tonite.

[Jim2]

Hook up your leakage tester to #6 then with the lower valve cover removed tap on the rocker with a plastic hammer while watching your gauge and see if it improves. Could be a tiny particle dislodged while removing the spark plug.

[cmcfaul]

Glad u figured it out

Chris

[dannobee]

Glad you got it figured out! It sounded too random to be crank or cam speed related.

[H/O Driver]

Starting a new thread for the #6 cylinder leak down issue.

No. 6 Cylinder Leak Down Problem

Thanks for all the help so far!

[smokintr6]

You need to very carefully inspect how much material has transferred from the flywheel to the crankshaft. I would guess you will be scrapping one or both pieces. It's really hard on the interface surface to run loose. Especially check the surface where the flywheel is a slight press fit. This is definitely not the first 6 bolt flywheel to come loose. Search other threads, but I believe there is some talk about it being permissible to over torque those fasteners *ive only owned 9 bolt porsches, so I am not an expert here*

[stownsen914]

And when you put the red loctite, apply it to the female threads before you install the flywheel. The idea being to make sure none of its makes its way in between the flywheel and the crank - it can cause false torque readings and facilitate things coming loose later when the stuff breaks down.

[smokintr6]

Originally Posted by stownsen914

And when you put the red loctite, apply it to the female threads before you install the flywheel. The idea being to make sure none of its makes its way in between the flywheel and the crank - it can cause false torque readings and facilitate things coming loose later when the stuff breaks down.

I use an old set of bolts, and fully install the flywheel. I then remove one bolt at a time and install a new bolt with red loctite, so there is never a change for the liquid to get between the mating surfaces. I use a paint marker on the new bolts so I don't get lost.

[stownsen914]

Originally Posted by smokintr6

I use an old set of bolts, and fully install the flywheel. I then remove one bolt at a time and install a new bolt with red loctite, so there is never a change for the liquid to get between the mating surfaces. I use a paint marker on the new bolts so I don't get lost.

I'm told the Loctite can still wick between the mating surfaces, and that the preferred way for flywheel bolts is to apply to the female threads. I'd guess that most people do similar to what you describe though.