Coolant mixed in with oil resulting in engine cutting mid-corner
 

2006 Carrera S with 98k miles

I was running my 997 at Thunderhill West when I noticed the oil pressure was low (at 3) on the straightaway and going into turn 2 mid corner a Check Engine light came on and then the engine shut off. There was some black smoke coming from the engine bay. I noticed my coolant ran low and there is a milky white residue in the oil filler tube. Also the oil level is now maxed out when it wasn’t before.

Car is getting towed to a shop for inspection but I’m playing through the scenarios: I’m guessing blown head gasket?

Don’t think it’s oil starvation because I would have heard rod knock or something, right?

And thinking ahead - what’s the going rate for a 997 roller with Ohlins R&T coilovers and GT3 LCA’s?

Even if I wanted to get this repaired I’m not so sure about using this engine for continued track abuse - thoughts? I’ve had 50+ joyeous track days out of this car.

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That is not good. If you are lucky it is a head gasket. I have to reluctantly say it is probably worst than that, thrown rod, the engine is toast. It will be many $$$$$ to fix. Sorry.

Look at your oil filter for metal debris after you cut it open and check your spark plugs.

Low oil pressure isn't great. Since the engine light came on, pull the codes and see what they are. Good advice to check the filter since that's easy. Keep it so your shop can see it. Mixing of oil and coolant usually happens in the head. Head gasket or some other cylinder head failure could cause that.

No oil pressure for even 10 seconds will damage the rod and crankshaft bearings at high RPMs.


This is from my own experience ?.

Sorry about your intermix.

Haven't studied the 997 S critical engine failure issues and preventative procedures, but the 996 M96 suffers from the same failure when the plastic blades in the water pump break off and get lodged causing overheating and cracking at the head. Prevention is changing water pump every 7 years or so. Other intermix issues can be caused by AOS failure and to a lesser extent the oil cooler. This may not be relevant to the 997 S, but if you are looking for some thoughts, this may give you a rabit trail to go down.

Dropping the sump would be my first recommendation, but it's likely not going to tell you much other than if the engine will actually be rebuildable.

It's unlikely going to be a blown head gasket. I've never seen a blown head gasket, even with an engine that was overheated severely.

It's going to be a cracked cylinder, cracked head, or failed oil cooler (which is very unlikely but does happen once in a blue moon).

I don't understand why dropping sump would be preferable over cutting the filter open. Only so many reasons the engine shuts down on its own and given the fact the crankcase is filled with water, would seem like taking literally 10 minutes to inspect the filter media would be path of least resistance to getting an idea how toast the motor is.

My opinion is whatever caused the intermix likely to be less of an issue when compared to the damage the intermix did.

As to the value of a roller, throwing a dart, $15Kish... I would suggest the OP look into keeping the car and putting an LS in it. For the price of an M96 rebuild you can buy the motor (L92), dry sump it, stuff it with race parts and put a big ass cooling system around it. You will end up making 100-130 WHP more than a rebuilt M96 and have a world full of aftermarket support and parts availability.

That is what I said. Not likely a head gasket.

More likely a rod thrown through the top of the block piercing the coolant passage causing that coolant to flow into the sump and give the reading of a higher oil level. The black smoke billowing from the engine bay was coolant, oil and unburnt fuel boiling off in the hot cylinder.

A thrown rod is usually visually obvious from outside the engine. Big hole in side of block, lots of fluid on the ground coming out of that hole. Also loud noises coming from the engine. I'd go with Charles' assessment.

Not sure if the ‘06 still used steel frost plugs in the heads, but these caused many intermixes in the M96 generation engines.
The steel plug and aluminum engine heat at different rates and it’s possible it could have popped out. Particularly if you experienced a sudden coolant
loss and engine stoppage.
My 3.4 M96 engine failed this way.

Not necessarily, I've thrown a rod through the top of the engine and the engine still sort of ran and didn't leak any fluids externally. All the leaking was internal and the hole in block was obscured by the intake manifold and emission piping.

True.