Low temp thermostat?
01-05-2019, 09:39 PM
#16
Which is better - I don’t know and this debate won’t ever be resolved. All I can tell you is I wrote a big check to a guy who has forgotten more about these engines than most and he thinks the 160 is needed. If I didn’t trust Flat 6 I would have sent my car elsewhere.
01-05-2019, 10:39 PM
#17
Drifting
01-05-2019, 11:13 PM
#18
Drifting
This is automotive 101. If a car is running as it should and everything is working right, the normal operating temperature of the engine is dictated by the capacity of the cooling system to remove heat. The thermostat does absolutely nothing to affect the normal operating temperature of the engine.
The thermostat is is simply an orifice that opens around a set temperature. Since engines don’t run efficiently when they are below their normal operating temperature, the thermostat shuts off the flow of coolant through the system until the warming engine reaches a certain temperature—causing the engine to reach normal operating temp faster than if coolant were circulating (and removing heat) from start-up.
A lower T-stat causes the car to warm up slower. Some claim that a lower T-stat reduces the risk of bore scoring because of the architecture of these engines. I can’t argue with that, but I’m not going to do it on my daily driver. To me, a slower warm up doesn’t seem to have any benefits. No matter what you do, the difference between the warm up times with a 160 and a 180 are minimal anyway.
But out no matter which way you go, a lower temp T-stat will never lower your operating temperature, because that’s simply not what thermostats do.
The thermostat is is simply an orifice that opens around a set temperature. Since engines don’t run efficiently when they are below their normal operating temperature, the thermostat shuts off the flow of coolant through the system until the warming engine reaches a certain temperature—causing the engine to reach normal operating temp faster than if coolant were circulating (and removing heat) from start-up.
A lower T-stat causes the car to warm up slower. Some claim that a lower T-stat reduces the risk of bore scoring because of the architecture of these engines. I can’t argue with that, but I’m not going to do it on my daily driver. To me, a slower warm up doesn’t seem to have any benefits. No matter what you do, the difference between the warm up times with a 160 and a 180 are minimal anyway.
But out no matter which way you go, a lower temp T-stat will never lower your operating temperature, because that’s simply not what thermostats do.
01-05-2019, 11:59 PM
#19
On cars I built I included enough radiator, fan, and shroud so the thermostat would cycle during operation, thus regulating temperature.
If you think about that old Chevy or Ford you used to drive, if you pulled the thermostat the heater wouldn't work in the winter, since an open thermostat implied the coolant would cycle back to the radiator rather than through the heater core.
Additionally, just as a note, pulling the tstat could overheat the car since the coolant then cycles too quickly to exchange heat (this may not make sense from a thermodynamic standpoint, but it is true).
When we had a tstat stick closed in the middle of the desert we cut the core out and put the body back in to allow cooling, but we had to adjust speed per the temp gauge since we weren't regulating the operating temperature with the tstat anymore.
With a 160 or 180 tstat the warm up to around 160 will be the same. The warm up to 180 will be slower with the LTT. After 180 warming will be equal. Yeah, I've simplified this a bit, since the tstats don't snap open.
If you think about that old Chevy or Ford you used to drive, if you pulled the thermostat the heater wouldn't work in the winter, since an open thermostat implied the coolant would cycle back to the radiator rather than through the heater core.
Additionally, just as a note, pulling the tstat could overheat the car since the coolant then cycles too quickly to exchange heat (this may not make sense from a thermodynamic standpoint, but it is true).
When we had a tstat stick closed in the middle of the desert we cut the core out and put the body back in to allow cooling, but we had to adjust speed per the temp gauge since we weren't regulating the operating temperature with the tstat anymore.
With a 160 or 180 tstat the warm up to around 160 will be the same. The warm up to 180 will be slower with the LTT. After 180 warming will be equal. Yeah, I've simplified this a bit, since the tstats don't snap open.
01-06-2019, 12:21 AM
#20
Three Wheelin'
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If you read the quite technical but very interesting article from Hartech they also recommend it from their experience in the same way Jake Raby / Flat 6 innovations does.
It is all about cylinder 6 / which is most prone to bore scoring. Bank 2 cylinders have hoter coolant on the thrust side than bank one. The cylinder 6 bank (bank 2) has worse cooling than bank 1. On top of this the pressure side on cylinder 6 is the worst in that bank if I remember right (because of coolant flow direction/route). The increased heat in cyl 6 especially on the side where the rod apply pressure to the wall also cause worse lubrication of the wall and there is more risk that the oil splashed cylinder wall oil film is too fragile causing direct contact between cylinder and cylinder wall.
According to Hartech the risk is biggest when thermostat has not yet opened as this part of the cylinder will experience extreme heat that is much bigger than other cylinders before thermostat is opened. Thereby also more prone to poorly lubricated cylinder wall.
Even if thermostat is not replaced they recommend not lugging the engine on low rpm as the engine has much larger low rpm torque than previous models and really on the technical limit of what this design can handle with current cooling. And with the low coolant flow on low rpm:s or closed thermostat you have insufficient flow around the pressure side of cylinder 6.
Another thing they recommend is that before making the first full rpm pull, to gradually build up heat and make a longer revving up and by that gradually building up heat and making sure it's distributed in case thermostat just opened.
So - to sum up they recommend a low temp thermostat as it will faster distribute coolant to the very much extreme situation in cylinder 6. The earlier cylinder 6 /bank 2 get coolant flow the lower risk for bore scoring.
See from page 21.
https://www.hartech.org/images/downl...0(interim).pdf
It is all about cylinder 6 / which is most prone to bore scoring. Bank 2 cylinders have hoter coolant on the thrust side than bank one. The cylinder 6 bank (bank 2) has worse cooling than bank 1. On top of this the pressure side on cylinder 6 is the worst in that bank if I remember right (because of coolant flow direction/route). The increased heat in cyl 6 especially on the side where the rod apply pressure to the wall also cause worse lubrication of the wall and there is more risk that the oil splashed cylinder wall oil film is too fragile causing direct contact between cylinder and cylinder wall.
According to Hartech the risk is biggest when thermostat has not yet opened as this part of the cylinder will experience extreme heat that is much bigger than other cylinders before thermostat is opened. Thereby also more prone to poorly lubricated cylinder wall.
Even if thermostat is not replaced they recommend not lugging the engine on low rpm as the engine has much larger low rpm torque than previous models and really on the technical limit of what this design can handle with current cooling. And with the low coolant flow on low rpm:s or closed thermostat you have insufficient flow around the pressure side of cylinder 6.
Another thing they recommend is that before making the first full rpm pull, to gradually build up heat and make a longer revving up and by that gradually building up heat and making sure it's distributed in case thermostat just opened.
So - to sum up they recommend a low temp thermostat as it will faster distribute coolant to the very much extreme situation in cylinder 6. The earlier cylinder 6 /bank 2 get coolant flow the lower risk for bore scoring.
See from page 21.
https://www.hartech.org/images/downl...0(interim).pdf
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SeanPatrick31 (07-02-2022)
01-06-2019, 01:00 AM
#21
Drifting
Or, we could drive our cars at moderate speeds and RPMs until they are warmed up to operating temperature...as every owner’s manual on every car ever made suggests.
I’m in no position to argue with Jake Raby. I defer to his experience. But, the fact is that thermostats only affect normal operating temperature when they’re stuck closed. If I read another poster ask if a 160 degree thermostat will keep his car running cooler, I think I might go postal.
I’m in no position to argue with Jake Raby. I defer to his experience. But, the fact is that thermostats only affect normal operating temperature when they’re stuck closed. If I read another poster ask if a 160 degree thermostat will keep his car running cooler, I think I might go postal.
01-06-2019, 10:00 AM
#22
Rennlist Member
Question: Are 997.1 engines more prone to bore scoring than 997.2 engines?
More interested in engine design differences rather than failure statistics between one model or the other. What I mean by that is that the total amount of cars of each version might skew the statistics as well as the fact that the 997.1 cars are older and probably have higher mileages
More interested in engine design differences rather than failure statistics between one model or the other. What I mean by that is that the total amount of cars of each version might skew the statistics as well as the fact that the 997.1 cars are older and probably have higher mileages
01-06-2019, 10:20 AM
#23
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Originally Posted by Astur
Question: Are 997.1 engines more prone to bore scoring than 997.2 engines?
More interested in engine design differences rather than failure statistics between one model or the other.
More interested in engine design differences rather than failure statistics between one model or the other.
It's similar as with PDK. In the beginning everyone said it's perfect but now I start to see more and more threads on repairs. Comes with age and mileage.
Here is a thread where Jake Raby posted a pic with a 997.2 DFI with bore scoring so it does happen even though not many cases yet. However designs of the engines are different so I assume risk is not identical.
https://rennlist.com/forums/997-foru...ability-7.html
When you buy a used car there is always a risk as you don't know how it was driven. You also don't see early bore scoring with. An endoscope as it starts at the bottom of the cylinder ad is hidden even with piston in the lowest point.
01-06-2019, 01:06 PM
#24
Drifting
Or, we could drive our cars at moderate speeds and RPMs until they are warmed up to operating temperature...as every owner’s manual on every car ever made suggests.
I’m in no position to argue with Jake Raby. I defer to his experience. But, the fact is that thermostats only affect normal operating temperature when they’re stuck closed. If I read another poster ask if a 160 degree thermostat will keep his car running cooler, I think I might go postal.
I’m in no position to argue with Jake Raby. I defer to his experience. But, the fact is that thermostats only affect normal operating temperature when they’re stuck closed. If I read another poster ask if a 160 degree thermostat will keep his car running cooler, I think I might go postal.
this, and are 997.1 more prone to bore scoring than 997.2.......................
01-07-2019, 01:21 AM
#25
Former Vendor
People always look at this with the glass half full..
Consider not only the temperature that the thermostat first opens at, but also the point that it is fully open, giving the cooling system maximum cooling volume, and heat exchange.I have found it beneficial to keeping both sides of the engine running cooler if the coolant volume is increased, this is especially true for bank 2.
It takes a lot of data to determine what works, certainly more than a stock coolant temperature sensor, and gauge (or even OBDII). The stock coolant temperature sensor is in the front console of the engine.
Consider not only the temperature that the thermostat first opens at, but also the point that it is fully open, giving the cooling system maximum cooling volume, and heat exchange.I have found it beneficial to keeping both sides of the engine running cooler if the coolant volume is increased, this is especially true for bank 2.
It takes a lot of data to determine what works, certainly more than a stock coolant temperature sensor, and gauge (or even OBDII). The stock coolant temperature sensor is in the front console of the engine.
03-07-2019, 01:57 PM
#26
Three Wheelin'
So I am looking at this LN Engineering LT thermostat for my 997.2, but the site states the previous.
Has any 997.2 owners run into this CEL problem?
03-09-2019, 05:32 PM
#27
Three Wheelin'
Anyone?
03-10-2019, 01:43 AM
#28
I’ll offer a unique data point. My 2009 3.6 came back with a LTT when it received a new engine under CPO. Oil temp pretty much plateaus at 180 for full warm up. It will only get to 200 after a solid 30 minutes of driving, and if I give it some gradual pushing (a little throttling in the 3500-4000 range but never beyond 4000) after it gets to 180. Or it is hot day (>90F) it will plateau at 190ish to 200 after the solid 30 min drive.
i did call my dealership who did all of the work to qualify this and their advice was the car is at proper oil temp warm up when it hits 175-180. However I still take that advice with a grain of salt.
TLDR - If I drive it easy, it will stay at 180 all day, unless it is pretty hot day....
i did call my dealership who did all of the work to qualify this and their advice was the car is at proper oil temp warm up when it hits 175-180. However I still take that advice with a grain of salt.
TLDR - If I drive it easy, it will stay at 180 all day, unless it is pretty hot day....
03-10-2019, 09:51 AM
#29
Three Wheelin'
I’ll offer a unique data point. My 2009 3.6 came back with a LTT when it received a new engine under CPO. Oil temp pretty much plateaus at 180 for full warm up. It will only get to 200 after a solid 30 minutes of driving, and if I give it some gradual pushing (a little throttling in the 3500-4000 range but never beyond 4000) after it gets to 180. Or it is hot day (>90F) it will plateau at 190ish to 200 after the solid 30 min drive.
i did call my dealership who did all of the work to qualify this and their advice was the car is at proper oil temp warm up when it hits 175-180. However I still take that advice with a grain of salt.
TLDR - If I drive it easy, it will stay at 180 all day, unless it is pretty hot day....
i did call my dealership who did all of the work to qualify this and their advice was the car is at proper oil temp warm up when it hits 175-180. However I still take that advice with a grain of salt.
TLDR - If I drive it easy, it will stay at 180 all day, unless it is pretty hot day....
03-23-2019, 02:07 AM
#30
Three Wheelin'
Last call. Anyone get a check engine light using a low temperature thermostat?