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Spot on. I've seen both scoring (based on the failure of the Al-Si cylinder system common to all Alusil/Lokasil cylinders) in all bores as well as seizing as Baz has described. The factory clearances are ridiculously tight. I measured a new block and pistons at .0007" total clearance at the gauge point, so it's easy to see if there are latent stresses in the castings that allow the bores to move, why the pistons seize.
I found this in the Porsche Technik specifically in regards to the 9A1 Turbo engine (introduced in 2010). It shows that Porsche did additional heat treatments to the Turbo crankcase to stabilize the casting. I wonder if this was adopted for the NA 9A1's in later model years as Porsche learned more about the phenomena.
I found this in the Porsche Technik specifically in regards to the 9A1 Turbo engine (introduced in 2010). It shows that Porsche did additional heat treatments to the Turbo crankcase to stabilize the casting. I wonder if this was adopted for the NA 9A1's in later model years as Porsche learned more about the phenomena.
Great info. That extra heat treating most definitely reduces the cast in stresses in the block by converting much of the austenite structure to martensite. Cryogenic treatment of cast components has been proven to stabilize castings by relieving these built-in stresses as the process converts the rest of the austenite crystal structure to martensite, creating a more consistent grain structure.
Once this creeping/seizing starts, is there any way to mitigate it or is it set in motion?
Unfortunately, no. The best thing you can do is use service your engine well with oil that supports the Al-Si cylinder system, ideally one with high moly and a robust anti-wear package. Shorter drain intervals are a must considering the higher level of fuel intrusion on direct injected engines.
As a 2010 Cayman base owner for 6 years I periodically find my way back to this scary thread. All cars and all engines have some inherent issue. Porsche is certainly not immune. As in life just drive and enjoy the car while you have it.
Great info. That extra heat treating most definitely reduces the cast in stresses in the block by converting much of the austenite structure to martensite. Cryogenic treatment of cast components has been proven to stabilize castings by relieving these built-in stresses as the process converts the rest of the austenite crystal structure to martensite, creating a more consistent grain structure.
Yeah, I'm not sure if they are describing a cryroheat treatment or a more traditional advanced heat treatment (solution heating, quenching, then artificial aging). From reading about it I get the impression the processes do the same general thing you describe, but cryroheat does more of it. I have a 9A1 turbo so it would be nice if it was cryroheat. Either way the second heat treatment (artificial aging) seems like a key step in crankcase stability as it speeds up the "settling" of the casting which could normally take years.
I found this reference in a Kolbenschmidt document on Alusil blocks that seems to describe a similar process:
Edit: Adding that the advanced heat treatment described in the Porsche Tecknik is supposedly unique to the 9A1 Turbo but that was written around 2009. Baz has described the seizing issue as more prevalent in the early NA engines (though still quite rare). I wonder if Porsche adopted it for the NA 9A1's at a later date and improved their reliability. The Kolbenschmidt document talks about Audi adopting it "in the future" for "absolute high performance engines" so it was not a run-of-the-mill process when the document was published.
You’ll likely find the issue on cylinder 1 most prominent.. If so, I know why. I’d start scoping on that cylinder first..
What is your hypothesis for #1? Curious as Ive seen many 9A1s now with all perfect L side bores, and all R side bores that are hammered (and of course every other combo you can think of).
What is your hypothesis for #1? Curious as Ive seen many 9A1s now with all perfect L side bores, and all R side bores that are hammered (and of course every other combo you can think of).
What does "many" and "hammered" mean? So far we've seen photos from one engine with some scrapes, but nothing like M96/97 where the piston gouges so deeply it virtually welds itself to the wall. It may have ended up that way eventually, but it's not there yet. I'm not questioning your experience, but trying to get some actual hard data rather than hearsay.
Did your car have a history of being driven hard when the oil was not up to operating temp?
What does "many" and "hammered" mean? So far we've seen photos from one engine with some scrapes, but nothing like M96/97 where the piston gouges so deeply it virtually welds itself to the wall. It may have ended up that way eventually, but it's not there yet. I'm not questioning your experience, but trying to get some actual hard data rather than hearsay.
Did your car have a history of being driven hard when the oil was not up to operating temp?
Agreed these pics are nowhere near the M96/97 smeared piston pics. Still, these mild looking scores dont get better, and Ive never seen any type of oil change/oil type/driving operation style stop them in their tracks.
>50% of the 9A1 engine vehicles that pass through my shop have scoring like the pictures shown. 50% of those vehicles also eat oil at a rate equal to or in excess of 1L per 1500 mi travelled, some will foul the oil in less than 1000 miles to the point where the oil reeks of fuel. The other 50% appear to run "asymptomatically", until they don't.
Hammered: Needing mechanical reconditioning to mitigate excessive oil consumption/noise. Do they run? Sure. Was my choice of wording alarming, perhaps.
I really have no idea how my car was driven as I bought it used from a Porsche dealer.
Last edited by advrider1967; 10-12-2021 at 07:46 PM.
2007 C2S MT with 90K miles. 4th owner of a very well maintained vehicle from Phoenix/Tuscon area. I’ve had it for 14 months, clocked 11,000 miles as a DD. Just noticed in the past couple of weeks Oil Temps approaching 250 degrees after 20-30 minutes of driving. And the Water Temp is coming off the 175 position to 180 degrees. Never seen that behavior before. And the front radiator fans are running almost all the time now. I never use AC, mostly go with the top down. And outside temperatures here in San Diego are cooling off. (I checked the Temp sensor in the engine compartment - looks normal). I have no classic symptoms of bore scoring, but my searches on RL have led me here. I have fully embraced the paranoia. LOL. Thoughts?
2007 C2S MT with 90K miles. 4th owner of a very well maintained vehicle from Phoenix/Tuscon area. I’ve had it for 14 months, clocked 11,000 miles as a DD. Just noticed in the past couple of weeks Oil Temps approaching 250 degrees after 20-30 minutes of driving. And the Water Temp is coming off the 175 position to 180 degrees. Never seen that behavior before. And the front radiator fans are running almost all the time now. I never use AC, mostly go with the top down. And outside temperatures here in San Diego are cooling off. (I checked the Temp sensor in the engine compartment - looks normal). I have no classic symptoms of bore scoring, but my searches on RL have led me here. I have fully embraced the paranoia. LOL. Thoughts?
Remove the front bumper (or have a reputable shop do it if you're not the DIY type) and clean between the AC condensers and the side radiators if it hasn't been done. That area can get clogged with debris and you'll be amazed what you'll find in there. Add some radiator grills like the ones from Rennline while the bumper is off so it doesn't happen again anytime soon. A 3rd radiator can also work wonders and the kit is relatively inexpensive.
If you haven't replaced the water pump or know if it has been done previously, now would be a good time to do it. The 997.1's aren't known for having water pumps that can make it the distance.
Consider adding a low temp thermostat. Lot's of threads here on the benefits and why they're important. If you're going to do a cooling system refresh anyway, it's cheap insurance. New coolant wouldn't be a bad idea either.
2010 Carrera 4 3.6L
Ownership: 2 years
Purchased with 109xxxkms and currently have roughly 138xxxkms
I may have a possible bore scoring failure. Still unsure of what may have caused it but I have a feeling it may be due to a mix of hard driving, lack of cooling(no 3rd rad) and a clogged pass side cat(running too rich due to a failing o2 possibly). Mechanic used a scope and also took apart a few parts for inspection.
- scoped inside cylinders and one has some light scoring
- engine is hard to turn over manually
- cogged up passenger side cat
- tons of metal dust found at the bottom of the pan once removed.
Back story:
- car has been driving fine and maintenance has been up kept
- multiple oil changes
- never left the car to idle longer than 30-45sec
- drove with caution until safe engine temps
- 6-8 track days completed this year
- modified exhaust and had an exhaust gasket leak for a month before finding it
- replaced all spark plugs and coil packs
- did another exhaust modification to remove side mufflers
- car drove fine for about 10-12 days and started misfiring with a flashing cel
- towed car to shop and this is the result
10-07-2021, 02:21 PM
