flatovercrest

Hi, I have a new for me 997.1 C4S, 52K miles that has checked healthy to any bore scoring issues. I know a lot of discussions here on the subject, but how do you prevent the problem from occurring?
Car is occasionally driven (more of a weekend car, when I have the time.. which isn't much) and I live in the Idaho mountains, which can be an issue when it comes to cold temps.
I do plan to change the oil more often than required if that's already a preventive thing.
Thanks.

rtl5009

Third radiator. Low temp thermostat. Oil change every six months with a high moly content oil. DT40/ Motul 300v/ pick your favorite add LM MoS2

JAAM

This thread

NAMR6MT

You can aid in prevention by performing the following procedures. There is no definitive way to absolutely prevent scoring except by installing Nikasil plated cylinders.

-Top Tier fuel
-Avoid idling after starting
-Frequent oil changes based upon mileage and time in service
-Avoid short driving distances. Allow the thermostat time to open.
-I add a dose of Marvel Mystery Oil to the gas tank when fueling up. This helps keep the injectors clean, along with the detergents in high quality gas.
-Replace old injectors/plugs/coil packs

Petza914

Everything said here and don't use the car in really cold weather. It effects Northern climate cars more than southern climate cars and also effects the 3.8L S cars more than the 3.6L base cars because of the thinner cylinder walls that result from the larger displacement.

What happens is during the warm up process from a very cold engine, the regular 180 degree thermostat that doesn't open until 180 degrees F and ain't fully open until about 212 F combined with the thinner cylinder walls of the larger displacement 3.8L engine allows the cylinders to expand faster than the Pistons and get a little sloppy in the bores. This slop allows the Pistons to rock and the skirts to make contact with the walls down at the bottom of the stroke when they change direction. Once the coating on the piston skirt is worn away and the cylinder wall scratched, it just gets worse from there. This is why cylinder 6 and then cylinder 5 are the most prevalent for scoring - it's because those are the furthest away in the coolant flow path so they stay hotter longer than the other cylinders.

The 160 degree low temp thermostat allows for a more gradual warmup of the cylinder walls because the coolant starts flowing earlier and then the cylinders don't expand at a faster rate than the pistons, so they don't allow the piston rock that occurs in the .1 engines that causes the scoring.

Scoring in the .2 engines has a different cause and is actually a piston seizure in the closed deck engine at the bottom of the stroke and happens when the cylinder gets too tight, not too loose. It wouldn't surprise me if this happens to more base engine cars than S cars in the .2 series, but it's so rare in the 9A1 .2 engine, it's essentially a non-issue.

Fullyield

Agree. You are doing the right strategic thing by immediately educating yourself on the causes as explained by others here and how best to prevent it.

Cmg Porsche

My mechanic advises not start them and idle especially in cold weather and don't lug the engine (driving in high gear vs the speed ... keep the revs up).

groovzilla

I think I remember reading sometime ago that in cold climates having a heater near the engine that can be turned on to warm up engine prior to starting can help.
But in this scenario you would have to return to garage or drive into someones living room if you were going to turn off car and restart to get home.

frederik

Let's not get overly cautious. The main thing is that many people try to be nice to their cars and warm them up idling in the driveway before driving off, and this is not good. Just start it, drive away immediately, and keep the revs below 3000 until the engine gets warm. Easy.

rileyracing1

No one mentioned to drive the car a little hard now and then ...These babies were meant to be taken thru the gears ...

Carreralicious

Driven hard and now possible failure?…
997.1 base engine fail on track:

Petza914

That doesn't seem good. His oil temps were in excess of 250 degrees at least a few times and there were a couple of turns where he was over 6,000 RPM and his pressure was at 3-3.5 bar. I've never seen this low a pressure at that type of RPM in my .1 car even with oil temps at 250 with the MantisSport baffled deep sump with windage tray. He was also running a complete gear higher than I would be almost all the time, but maybe I don't have to do that because of the supercharger and with the NA base 3.6 engine that's where the power is. He said he was short shifting to keep the oil temp lower, but I didn't see any of that going on.

Post up part 2 once there is one if you would. I'm interested in the diagnosis of what has failed on Bank 1 with cylinder 2. Maybe it was just the AOS that fouled the plug. I sold the new MS AOS I had before installing it as there wasn't really a good way to adapt it to the regular Carrera engine that I could come up with.

Carreralicious

I didn’t notice that he had such low pressure at 6K revs. Wonder what could’ve caused that.

Petza914

His oil either broke down and thinned out when it got that hot or his deep sump doesn't have baffles around the pickup location and or a windage tray. The windage tray not only prevents the crankshaft from whipping the oil but also limits how much of it can slosh away from the central pickup.

Bomba

Does this really work? I've always seen Marvel Mystery Oil as kind of a snake oil gimmick, like Z-Max.