997.2 TT engine Failure
04-01-2022 | 03:42 PM
#16
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From: DFW, TX
Starting/general use in very cold temps seems to be one of the common themes for bore scoring in the M96/M97 NA cars.
I gotta think the number of .2TT owners who daily their car for years in the winter in a Canadian climate is pretty small.. might be why no one has seen this before.
I gotta think the number of .2TT owners who daily their car for years in the winter in a Canadian climate is pretty small.. might be why no one has seen this before.
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04-01-2022 | 04:48 PM
#17
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Drifting
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@Anakin Skywalker Thanks for your detailed feedback! First of alI, I think that is awesome that you daily drive your Turbo during winter. Your feedback is actually very interesting. Letting the engine warm up before raising the revs, all good things.
During the winter, the engine takes longer time to warm up compared to summer. Higher coolant temperatures in the cylinder jackets help to evaporate the fuel that deposited on the cylinder walls after cold start.
It takes more time for the fuel on the cylinder walls to evaporate after these relatively low temperature cold starts, which themselves requires additional fuel to be injected for the engine to start and to operate in those cold conditions, thus leading to higher level of oil dilution by fuel.
There is obviously nothing wrong with the way you drive and maintain the car since your driving profile should have been taken into account by Porsche engineers during the development of the engine (both NA and Turbo).
I'd be curious to ask Porsche :
- if they see more occurrences of bore scoring on this engine for customers living (and using regularly their cars) in northern areas vs southern areas. My guess is they should see more occurrences happening in colder climates.
- what is oil dilution rate they consider acceptable before having to change the engine oil : 10%, 15%?
I don't know if this is too late but it would be interesting to sample the oil from the failed engine and have Porsche check the dilution rate by a lab.
With your new engine, if you want to tackle this dilution rate topic, I would suggest the following actions by order of increased complexity :
1. The easiest solution would be to perform one or two additional oil change in the winter times.
2. During the time you use the car in the winter, if you regularly check the oil level (let's say every 500km) and see an increase, it means your dilution rate increases (more fuel in the engine oil). It can then give you an indication that you need to perform an oil change earlier so as to keep the dilution rate as little as possible. I am not sure however if that would be reliable - you would need to check the oil level in the same conditions every time.
3. You sample oil from your engine every 1000km, have it analyzed by a lab and check the actual oil dilution rate. Then, you have your answer on when to perform engine oil changes.
For the sake of clarity, I am not saying engine oil dilution killed your original engine because I don't have data to prove it but we know that oil dilution is an aggravating factor for engine reliability.
In any case, your driving profile is not atypical and I suppose (hope) that Porsche engineers may already have taken it into account.
Just out of curiosity, did the dealer told you what were the engine code(s) that triggered the CEL? The engine code(s) usually have to come up twice or thrice before the CEL is ON so if you have an OBD reader, the presence of this codes at the 1st occurrence might tell you something is happening so you might also be able to use this information to know when to make your engine oil change (although that might be a bit too late to preserve the engine).
During the winter, the engine takes longer time to warm up compared to summer. Higher coolant temperatures in the cylinder jackets help to evaporate the fuel that deposited on the cylinder walls after cold start.
It takes more time for the fuel on the cylinder walls to evaporate after these relatively low temperature cold starts, which themselves requires additional fuel to be injected for the engine to start and to operate in those cold conditions, thus leading to higher level of oil dilution by fuel.
There is obviously nothing wrong with the way you drive and maintain the car since your driving profile should have been taken into account by Porsche engineers during the development of the engine (both NA and Turbo).
I'd be curious to ask Porsche :
- if they see more occurrences of bore scoring on this engine for customers living (and using regularly their cars) in northern areas vs southern areas. My guess is they should see more occurrences happening in colder climates.
- what is oil dilution rate they consider acceptable before having to change the engine oil : 10%, 15%?
I don't know if this is too late but it would be interesting to sample the oil from the failed engine and have Porsche check the dilution rate by a lab.
With your new engine, if you want to tackle this dilution rate topic, I would suggest the following actions by order of increased complexity :
1. The easiest solution would be to perform one or two additional oil change in the winter times.
2. During the time you use the car in the winter, if you regularly check the oil level (let's say every 500km) and see an increase, it means your dilution rate increases (more fuel in the engine oil). It can then give you an indication that you need to perform an oil change earlier so as to keep the dilution rate as little as possible. I am not sure however if that would be reliable - you would need to check the oil level in the same conditions every time.
3. You sample oil from your engine every 1000km, have it analyzed by a lab and check the actual oil dilution rate. Then, you have your answer on when to perform engine oil changes.
For the sake of clarity, I am not saying engine oil dilution killed your original engine because I don't have data to prove it but we know that oil dilution is an aggravating factor for engine reliability.
In any case, your driving profile is not atypical and I suppose (hope) that Porsche engineers may already have taken it into account.
Just out of curiosity, did the dealer told you what were the engine code(s) that triggered the CEL? The engine code(s) usually have to come up twice or thrice before the CEL is ON so if you have an OBD reader, the presence of this codes at the 1st occurrence might tell you something is happening so you might also be able to use this information to know when to make your engine oil change (although that might be a bit too late to preserve the engine).
The connection between cold weather operation and oil dilution makes sence. I agree with doing oil testing from now on and I will likely do a mid winter oil change from now. This engine failure has challenged some of my assumptions about my car, one of which is that it is bullet proof in all weather.
The comments on this thread have given me a lot of good ideas. I expect to meet my tech next week at the dealership ( who is excellent). He is always happy to walk me through what he is doing to my cars so I will raise the codes thrown in the failure and specifics of the bore scoring, as well as the parts not replaced under warranty.
-30.5 Celsius
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04-03-2022 | 02:09 AM
#18
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From: seattle, washington
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04-04-2022 | 11:59 AM
#19
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From: Momence, IL
@Charles Navarro Thanks Charles for all the inputs. 6 month for oil changes seems very frequent, it is the same recommendation for 991.1 3.8L 9A1 engine? I don't drive often my GTS (once a month) due to my busy schedule and my next oil change is forecast in 16 months...
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04-05-2022 | 01:31 AM
#20
Racer
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From: Los Angeles, CA
I stand by by recommendation to change the oil every 6 months regardless of mileage. Not driving these cars or driving them short distances and or in cold climates all are horrible for the engine and the oil. Combustion byproducts combine with moisture to create acids that cause corrosive wear even if the engine is stationary.
04-05-2022 | 10:39 AM
#21
RL Community Team
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I stand by by recommendation to change the oil every 6 months regardless of mileage. Not driving these cars or driving them short distances and or in cold climates all are horrible for the engine and the oil. Combustion byproducts combine with moisture to create acids that cause corrosive wear even if the engine is stationary.
LOL.
In all seriousness, love to see people with REAL expert opinions post here. What would you consider short distances? I live in Houston and it's not uncommon for my car to sit for a week at a time, but usually no more than two. But I do get it up to temp for a good half hour (usually) when I drive it?
04-05-2022 | 11:18 AM
#22
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Short distances are where you aren't bringing the engine up to full operating temperature or doing so for a short distance and then shutting the engine off. Probably the single most important thing you can do on these engines, or any engine quite frankly, is to change your oil frequently with a high quality oil (Driven DI40 for direct injected engines, Driven DT40 for port injected engines).
04-05-2022 | 01:32 PM
#23
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From: Momence, IL
Psssh, what would you know about engines?
LOL.
In all seriousness, love to see people with REAL expert opinions post here. What would you consider short distances? I live in Houston and it's not uncommon for my car to sit for a week at a time, but usually no more than two. But I do get it up to temp for a good half hour (usually) when I drive it?
LOL.
In all seriousness, love to see people with REAL expert opinions post here. What would you consider short distances? I live in Houston and it's not uncommon for my car to sit for a week at a time, but usually no more than two. But I do get it up to temp for a good half hour (usually) when I drive it?
Let's say you start the car and drive it less than 30 minutes in the winter or heaven forbid, you let the car idle excessively - the oil then probably needs to be changed every three months.
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04-06-2022 | 08:31 AM
#24
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Drifting
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My definition of a short distance is variable. In the winter, it's going to take much longer for the car to get to temp. Ideally, the oil needs to get to and stay at 215-220F for a little bit to vapor off moisture.
Let's say you start the car and drive it less than 30 minutes in the winter or heaven forbid, you let the car idle excessively - the oil then probably needs to be changed every three months.
Let's say you start the car and drive it less than 30 minutes in the winter or heaven forbid, you let the car idle excessively - the oil then probably needs to be changed every three months.
The question in my mind is whether there is something in the nature of a cold start (ie sub zero) which compromises the engine over time because for example piston ring tolerances aren’t the same at that temperature. Is that possible? Is it possible that the engine oil isn’t effective at that temperature because of viscosity changes?
My car has had a lot of cold starts in the 6 years I’ve owned it.
04-06-2022 | 11:13 AM
#25
Three Wheelin'
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From: Exton, PA
Every start presents opportunities for wear in an engine. That's why some guys will pull the fuel pump fuse to build pressure before a start after an oil change (I'm one of them).
Proper weight oil for you environment is important, but I am not familiar with any cold weather recommends for a 911. If you are consistently starting the car below freezing, then looking into this may be worthwhile. Maybe others have some suggestions.
Normally cold starts wouldn't be a great concern over the life of the car, as long as you wait the minute or so for the idle to drop before going and keep it relatively light on throttle and below 3000 RPM until completely warm.
Ed
Proper weight oil for you environment is important, but I am not familiar with any cold weather recommends for a 911. If you are consistently starting the car below freezing, then looking into this may be worthwhile. Maybe others have some suggestions.
Normally cold starts wouldn't be a great concern over the life of the car, as long as you wait the minute or so for the idle to drop before going and keep it relatively light on throttle and below 3000 RPM until completely warm.
Ed
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Watson (04-06-2022)
04-06-2022 | 12:25 PM
#26
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Just wanted to clarify, in light of the fact that this individual is in Canada and has a direct injected engine: Do you still suggest a 5W40, all else equal considering the aforementioned facts? I personally would run DI40, a 0W40, in this engine for more reasons than the cold viscosity. Thank you for the information.
04-06-2022 | 12:40 PM
#27
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FYI My 997.2 TT whose engine failed last month has always had engine oil up to temperature (80deg C)for at least 40 mins each operating cycle.
The question in my mind is whether there is something in the nature of a cold start (ie sub zero) which compromises the engine over time because for example piston ring tolerances aren’t the same at that temperature. Is that possible? Is it possible that the engine oil isn’t effective at that temperature because of viscosity changes?
My car has had a lot of cold starts in the 6 years I’ve owned it.
The question in my mind is whether there is something in the nature of a cold start (ie sub zero) which compromises the engine over time because for example piston ring tolerances aren’t the same at that temperature. Is that possible? Is it possible that the engine oil isn’t effective at that temperature because of viscosity changes?
My car has had a lot of cold starts in the 6 years I’ve owned it.
In my opinion the bore scoring issue in the 997.2 TT and later has a lot more to do with the fact that Porsche ditched Nikasil lined cylinders and went to Alusil to save money. The clearances between the piston and cylinder walls are insanely tight on your engine and all the cold starts in the brutal cold like shown in your image are almost for sure a key contributor to the bore scoring.
Last edited by silver_tt; 04-06-2022 at 12:47 PM.
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04-06-2022 | 01:25 PM
#28
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From: Momence, IL
FYI My 997.2 TT whose engine failed last month has always had engine oil up to temperature (80deg C)for at least 40 mins each operating cycle.
The question in my mind is whether there is something in the nature of a cold start (ie sub zero) which compromises the engine over time because for example piston ring tolerances aren’t the same at that temperature. Is that possible? Is it possible that the engine oil isn’t effective at that temperature because of viscosity changes?
My car has had a lot of cold starts in the 6 years I’ve owned it.
The question in my mind is whether there is something in the nature of a cold start (ie sub zero) which compromises the engine over time because for example piston ring tolerances aren’t the same at that temperature. Is that possible? Is it possible that the engine oil isn’t effective at that temperature because of viscosity changes?
My car has had a lot of cold starts in the 6 years I’ve owned it.
04-06-2022 | 01:27 PM
#29
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From: Momence, IL
Just wanted to clarify, in light of the fact that this individual is in Canada and has a direct injected engine: Do you still suggest a 5W40, all else equal considering the aforementioned facts? I personally would run DI40, a 0W40, in this engine for more reasons than the cold viscosity. Thank you for the information.
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Watson (04-06-2022)
04-06-2022 | 01:36 PM
#30
Burning Brakes
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I stand by by recommendation to change the oil every 6 months regardless of mileage. Not driving these cars or driving them short distances and or in cold climates all are horrible for the engine and the oil. Combustion byproducts combine with moisture to create acids that cause corrosive wear even if the engine is stationary.