Diagnostic process
 

At a DE car suddenly down on power and making unhappy noises. I shut it down and coasted to garage. Once it's towed home, what should I check? Turn it over by hand? Pull valve covers and inspect? Compression and leakdown? Oil filter contents? Short of a full tear down what should I look at first?

visual inspection
 

First things first - visual inspection. This is #5. Is that the base gasket protruding? Can broken head studs cause that?http://forums.pelicanparts.com/uploa...1452462349.jpg

A broken stud doesn't bring it down on power necessarily but jumping time on a cam can cause problems and still get you home.
Put car up on one side and pull lower valve cover and take a look. More than 1 broken stud, broken rockers, rockers shafts moving off location, rocker falling off the shaft.
Bruce

Thanks for the guidance, Bruce. I'll pull the valve cover first thing tomorrow.

Already drained the oil. Metal on both magnets. :(

That is the base gasket - I can slide it up and down, so the cylinder is quite loose.

Thanks again, Bruce.

Lots of junk on the magnet, a rotational clicking, you're probably looking at spun bearing on a rod. This failure eats up the crank very quickly and it's expensive to repair.
Just start taking it apart until you find the defect or if you're unsure of your work, send it out.
Bruce

oil drain plug debris
 

Chunks on magnets, check.
http://forums.pelicanparts.com/uploa...1452523534.jpg

That's the oil tank plug on the left with the big chunks. They're flat and 1.46mm thick. Piston ring fragment? If so, how would they migrate from the crankcase to the oil tank? Wouldn't that require getting past the oil pickup screen, through the pump and through the oil filter?

I'll pull the valve cover this morning and see what's there.

Stay tuned.

I hear your thoughts. I have to admit I always thought it out as things can't get back to the oil cooler because all oil is filtered, sent to the reservoir as clean oil..sounds like my mistake.
You're going to have to flush the cooler lines, trombone, thermostat and send the cooler out for sonic cleaning.
Another item. I don't see how you can have broken rings in the oil unless you blew up the piston or broke a valve and holed it tearing the ring grooves apart.
I'm sure you still have to look at the rod bearings...
Bruce

Pulled the right side exhaust valve cover. Headstuds intact. Rocker shafts have not moved. Rockers ok, but massive clearance on #5. Bent valve, right? Some FOD (foreign object, debris) in valve cover.

Probably time to quit poking around and just drop the motor for a tear down.

You replied while I was typing.

If you bent the valve, you have to look for piston damage Worse scenario is a broken valve with hole in piston and rod bent. Seen that several times.
Bruce

Photos of carnage
 

Bruce, don't you ever get tired of being right?

Did this start as detonation? The piston top is gone above the first ring.

What are the odds the crank is OK?

http://forums.pelicanparts.com/uploa...1452719211.jpg
http://forums.pelicanparts.com/uploa...1452719240.jpghttp://forums.pelicanparts.com/uploa...1452719321.jpg

There is a broken rocker on intake 5.
Nice valve face on the piston where it hit.
Looking for a reason, just looks like piston failure at the piston pin area
Youll have to spin the crank at a machine shop to check for a bend or runout.
Bruce

Case damage
 

Apparently the cylinder base lifted and bashed debris against the case. That's why the cylinder gasket was protruding and loose. Can the case be rescued? The damage to the surface where the cylinder sits is about 1mm deep. Can these (all 6, I presume) be re-machined and used with thicker base gaskets?

http://forums.pelicanparts.com/uploa...1452778959.jpg

The answer is yes. I'm doing one right now on a 3.2 that was previously cut 1mm. Not knowing it was done until it was after the first assembly, I've had to take it apart a couple times to make things right. EBS has .25, .50, and 1.0 mm base gaskets.
I'll catch grief over it but I would only fly cut the one cylinder base, clean the case inside of defect and rebuild.
Looks like you have alucil cylinders, as I recall old conversations, K&S pistons are cast, not forged, that may be why the piston blew up because of an inherent weakness.
Bruce

This kind of reminds me of the Far Side cartoon "Early Plumbers".
The caveman bending over the hole in the ground saying "Oooo, this not be cheap".

Sorry to see that this kind of blew up on you but will be interested in the direction you need to go to repair.

Bruce, cylinders are Mahle and magnetic. That means Nikasil, right?

I hear you about the case repair. Machining just one spigot should work so long as it is properly indexed off the others and the correct base gasket is used. In any event, I would certainly stamp the case. I saw the thread you posted with interference at TDC.

Thanks, Bill. I intend to crack the case today and see the condition of the crank.

First, this thread must be flagged because of the violent and disturbing nature of the pictures. That said...

It's $150 to deck all 6 spigots at a famous left coast machine shop. It can't be much less than that to set up and do just one. If you can deck it yourself, I guess it's more expedient to dress up that one spigot. If you have to send it out, it would make little sense at that price point to do just one. I personally would go into an OCD tail spin knowing one spigot was different from the rest.

Well, the situation is, everything will be different now....
It doesn't matter how much money you spend on the case, you can't make it perfect and you'll always be looking at the #5 base gasket area.
What would you resolve cutting the other 5 cylinder bases, you'll still look at #5 every time you get under the car.
My Raleigh machine shop can fly cut anything I need done, don't need to send it any further.
I just hope his crank is still straight.
Bruce

more carnage
 

Not what you want to see when removing the sump screen...
http://forums.pelicanparts.com/uploa...1452900877.jpg

This is most of the debris. I haven't raked out the crankcase yet. Of course, the insidious stuff is what has circulated through the lubrication system (internals, coolers, lines, tank...)
http://forums.pelicanparts.com/uploa...1452901006.jpg

You ll have shrapnel in the FI intake too on both sides and the airbox because the junk was blowing up from the pressure in the engine and sucking in on the good cylinders.
Bruce

Thanks for the warning. Not obvious it would travel there.

I wonder how much fine stuff get blown through the crankcase vent to the oil tank. I imagine it's just a tornado of oil mist and pulverized metal.

Take a look at at these main bearings. Surprisingly little embedded metal, it seems.
http://forums.pelicanparts.com/uploa...1452903999.jpg

Yes the mains actually look descent, not scratched through the rotation.
Bruce

Are the mains good enough to reuse?

There is 2 thought processes here. One to fix the fault and the other is to rebuild because you're there. The nice thing about the Porsche design is you can fix the fault.
You ll need a rod, P/C, head, rocker. Check the oil line in the carrier for damage from the rocker.
Remove the mains and mark exactly where they came from in the case to be reused.
Cleaning will be the biggest problems. Oil galleys in the case, galleys in the crank, how scratched up inside is the oil pump?
Etc, etc
Bruce

Oh my.

I think Bruce is correct. Cleaning is going to be at, or near, the top of the "difficult steps" list.

junk getting into lubrication system
 

You said it, Tom. It's going to be a nightmare.

The old race cars had a filter called a "grenade" to keep debris from the external oil system. It's a magnesium casting with a stack of fine mesh filters inside that attached to the motor in place of the internal cooler. I think the name was partly due to its shape but mostly due to it role when an engine "grenaded".

Here's one on a 906 (just aft of #6).

http://forums.pelicanparts.com/uploa...1452979001.jpg

Spun bearing, right?
http://forums.pelicanparts.com/uploa...1452983744.jpg

That's what they look like
Bruce

I'm sure there was a cheaper way to learn that. Wikipedia, maybe.

Here's the rod journal. No grooving I can detect with fingernail. Not glassy smooth like the others but not rough. Mikes out near low end of wear limit.
http://forums.pelicanparts.com/uploa...1452989931.jpg

Oh, I could have showed you several pictures but you asked after the fact...
Polish out the journal and see if you can straighten it out making it usable then get coated bearings to build up the thickness.
Mike on three different angles to check for oval
Bruce

Someone suggested the crankcase spigot can be welded to build it up and machined back to standard height. Is that feasible? The damage is shallow (about 1mm at deepest) and extends about 1.5 inch.

A machine shop will heliarc the low spot and flycut it up to standard.
At that point you might consider using the thicker fiber base gaskets to fill in better.
Bruce

crankcase repair
 

OK, I've been slowly working my way through the process of assessing damage, locating replacement parts and cleaning, cleaning, cleaning.

Here's the crankcase after repairs. The repair inside the spigot is obvious, there were also small repairs to the top of the spigot.

http://forums.pelicanparts.com/uploa...1457617306.jpg

metal in intake
 

Right again, Bruce. Here's the bottom end of the #5 intake runner and the breather line from the case to the oil tank.
http://forums.pelicanparts.com/uploa...1457617986.jpg


http://forums.pelicanparts.com/uploa...1457618019.jpg

The horror! So sorry to see this misfortune, best of luck getting her back in track shape!

Thanks, Chris.

The clean up has been an enormous task. The whole oil cooling and circulation system had to come out to be flushed, swabbed and ultrasonically cleaned.

In the process, I explored areas I've never seen - here's the inside of the air box.
http://forums.pelicanparts.com/uploa...1457623348.jpg
Note the metal flakes still present after flushing with carb cleaner and flooding twice with solvent. I had to open it up to really clean it.

The good news is I found my air leak.
http://forums.pelicanparts.com/uploa...1457623402.jpg
That's the o-ring that seals the throttle body to the air box protruding.

You found your air leak, so it's all been worth it......in the end
Bruce

Yep, finding the air leak is a plus. I'm also having the crank drilled for better oiling and installing a 964 oil pump. Not sure I can stand this much fun again - at least not soon.:(

http://forums.pelicanparts.com/uploa...1457634015.jpg