gla

I spent yesterday changing my water pump and putting in a 160 degree thermostat. I can't thank the DIY information from this forum enough. It was pretty straight forward with the instructions. A couple of the bolts were a pain and if I do it again I think I will remove the header to make things easy to reach. I did not this time because I did not have a new gasket and am a long way from a dealership. I did take off the mufflers and the cat that was in the way. The only thing I was disappointed in was the airlift device to refill the system. Maybe I did something wrong, but when I pumped the system to 27 lbs it collapsed the hoses and wouldn't hold enough pressure. I ended up just refilling the system and using the burp release to vent the air pockets. I had to take it for a drive to get the air out, but it worked great. By the way, my old water pump looked perfect upon inspection. The car is an 07 S Coupe with 21,000 miles. I changed it proactively as the car will be six years old this fall. Thanks again to all those who provided the DIY posts.

USMC_DS1

Congrats... great to see more DIYer with a successful WP replacement under their belt.

Spokane5150

Congrats on a proper install!

I see you went with a 160F thermostat. The stock opens at 186F and is fully open at 200F. In my opinion the 160F thermostat isn't good for your engine because it takes longer to come up to optimum temperature; basically your car runs rich longer especially in colder weather. All the thermostat does is help your engine come up to temperature faster by holding the coolant in the motor circuit longer, where all the energy (heat) is, then the thermostat opens and begins to divert the coolant to the radiators to maintain operating temperature +/-200F. Regardless of the thermostat temp setting the car will run at 200F because your engine is designed to run efficiently at 200F and most of all....the engine computer is set at 200F. The fans and heat dissipation from the radiators work as "One" to maintain 200F. If the motor starts to go over 200F the fans come on to maintain that temp; simple thermal dynamics. Installing a 160F thermostat will not change the operating temperature.

We can debate this but I don't see any value in a 160F thermostat. You may actually put more load on your cats and other sensors in the motor because the motor is running rich longer. A motor running rich is just as bad as running lean. Just say'n.....

If you want to help with potential spikes in the heat load you should upgrade to the third radiator.

fjasione997

http://www.pelicanparts.com/catalog/..._pg1.htm#item5

Spokane5150

Pelican is saying in opens earlier, with the lowered thermostat (160), what does this mean? Is this statement contradicting you or agreeing=?

I will be doing the WP change soon and I am confused.

Thanks

GSIRM3

I think that is exactly what Spokane is saying. I agree with Spokane on this issue.

chris.hanle

Spokane is saying the thermostat will open sooner to keep the water temp closer to "160". In cold days the water temp may not even reach the optimal 200 deg. Therefore prolonging rich issue (decrease mileage,increased carbon into cats ect). This may only be minimal, not sure on the extent.

holden997

Engine running constantly at lower temperatures can run richer and hurt fuel economy, do not heat up the crankcase and oil fast enough and hot enough to burn off excess moisture and water vapor in the crankcase causing premature sludge build up. Can cause additional carbon build up and lack of carbon burn off. Carbon build up in the intake ports, on the back of the intake valves and on the O2 sensors can lead to difficult starts, cold start stalling and cold idle problems.

gla

The low temperature (160 degree) thermostat is about as controversial as what brand of oil to use. After lengthy consideration I opted for the 160. Certainly the car will operate at the same temperature regardless of thermostat after the thermostat is fully open and the vehicle is at operation temperature. I was swayed by the argument that the low temperature thermostat may more likely prevent hot spots prior to full operating temperature. LN Engineering and Hartech convinced me, but clearly not everyone.

USMC_DS1

I contemplated the low temp t-stat as well as I had removed the original t-stat for inspection and to gain better access to my WP when I replaced it last year... but I decided against it in the end:
- I like to only change one component at a time in a system especially when an item is more mod then maintenance oriented. This helps with troubleshooting should something go wrong after the install of a component.
- I had installed the 3rd radiator prior to my WP replacement which had dropped my oil temp to 200+ degF during the winter months and 210+ degF during summer months at normal operating temps. Under a hard load/spirited driving sessions during the summer my oil temp remained below 250 degF after the 3rd rad install... a considerable improvement but the potential offset is the possibility of the temp not getting high enough to burn off moisture from the engine. It's been 10 months and a winter season since the 3rd rad install. I'm glad to report that I've notice zero evidence of moisture/gunk build up.

OP, as you've installed the low temp thermostat... I'm curious as to whether it takes a bit longer or maybe less time to warm up the oil temp to 200 degF vs. before the mod. I'm trying to gauge the positives and potential negatives of such a mod. BTW, I've noticed that it takes me longer now with the 3rd rad to warm up my oil temp to 200 degF so I drive an extra easy mile around the neighborhood before I'll consider loading the engine on the open roads. Not sure if the low temp stat works in a similar manner but please report back with your findings and any other changes you've noticed in the cooling system. I'd like to also understand the real impact of this mod over time... if that's possible. TIA

copmots

Hi all to clarify the low temp thermostat issue the thermostat is located on the return flow to the engine, not like in a lot of engines at the outlet. So in some circumstances after a hard drive the stat is fully open for maximum coolant flow. If the car is then say in traffic or stopped the stat may then start to close leaving coolant at a very high temperature in the engine block. If you then put the engine under a heavy load the temperature of the coolant at a point farthest from the thermostat which is cylinder number 6 is operating in extreme temperatures which can lead to bore scoring. A known issue. The lower temp stat keeps the coolant flowing thereby keeping the temp down at cylinder 6. This is my very simplistic view of the benefits of the low temp stat. For a full and very detailed explanation of the benefits of a low temp stat look at www.hartech.org in part5 of the buyers guide.

GSIRM3

Any ideas why the Porsche engineers weren't clever enough to figure that out ?

copmots

No idea on that one I'am afraid. All I can say is the coolant is flowing anti clockwise before it reaches the stat. From engine to radiators then back to engine thermostat when coolant is hot enough the stat opens. In nearly all circumstances this is fine but after a hard drive then a slight cooling period the standard stat starts closing. If the engine is then subject to heavy loading the temp at cylinders 6 is still very high and can lead to piston seizure and wear. As I say look at hartech web site for a more informative explanation. 997 @ 996 engine failure is pretty rare but when it does occur cylinder 6&5 suffer extensive bore scoring other cylinders remain unaffected. Maybe if Porsche engineers were to admit there was a problem in this area it may open the flood gates for engine failure claims? Who knows I'am just motor engineer of 30 years experience and believe that the same problem repeated is caused by the failure of a specific component or design fault.

GSIRM3

Are you saying that when the engine starts up and is cold, the coolant is pumped through the engine and out to the radiators and back to a deadhead against the closed T-stat until the coolant reaches the temperature at which the T-stat opens to allow coolant flow back to the engine?

copmots

Correct very strange design but that's how it works! I suppose in relative terms water cooled Porsches are a new design and haven't been about too long really. There is also an issue about gen1 head design which leads to overheating within the cylinders. The low temp stat just keeps the coolant flowing quicker and for longer.

cvtbenhogan

Super Interesting. Sounds like the classic tradeoff situation.

Would it be fair to say the 160 stat might be best for hot climates and more demanding/variable loads?

Is cylinder scoring more of an issue for the 996?