Installed water pump and 160 thermostat today

[kashmir]

Just in time for the dallas summer.

[shadrach74]

Good deal. Can you explain why you installed a 160df thermostat? No one (including those that sell them) has been able to give me a reasonable and scientific based answer as to why they are beneficial. Is there some advantage to having a longer warm up period?

[JFP in PA]

Originally Posted by shadrach74

Good deal. Can you explain why you installed a 160df thermostat? No one (including those that sell them) has been able to give me a reasonable and scientific based answer as to why they are beneficial. Is there some advantage to having a longer warm up period?

OK, here goes: The thermostat sets the baseline minimum operating temp for the engine; it is the temperature the engine returns to when running at a steady state (road speed air flow across the radiators). Because of the convoluted design of the M96/97 cooling system, particularly the engine passages themselves, these engine's typically run a bit hotter than the temperature at which the thermostat opens. As the result, with the OEM stat opening at 186F, it is not unusual for the engine to run 210-215F at steady state on a fully instrumented 986 (forget what the dash gauge say, they are well known for being both woefully inaccurate and non linear). Because of the cooling system layout, at that temp the engine is actually much hotter in some internal areas, and as the oil is always hotter than the coolant (even though the engine uses a oil to water heat exchanger).

Changing to a 160F stat tends to lower the steady state coolant temp to around 175F, and more critically lowers the oil temps by over 25F, which the oil likes much better (UOA's before and after have shown the oil actually shows better parameters for longer distances between changes with the 160F stat). And on a base car, adding both the 160F stat and the "S" oil cooler (nearly twice the capacity of the base unit) improves the oil life even more. In essence, lowering the coolant and oil temps translates into improved life for both the oil and the engine.

And once and for all, cars with 160F stats do not warm up more slowly; in fact, the tend to warm up more quickly as the warmed coolant starts to flow sooner, not later.

[Homeboy981]

Originally Posted by JFP in PA

OK, here goes: The thermostat sets the baseline minimum operating temp for the engine; it is the temperature the engine returns to when running at a steady state (road speed air flow across the radiators). Because of the convoluted design of the M96/97 cooling system, particularly the engine passages themselves, these engine's typically run a bit hotter than the temperature at which the thermostat opens. As the result, with the OEM stat opening at 186F, it is not unusual for the engine to run 210-215F at steady state on a fully instrumented 986 (forget what the dash gauge say, they are well known for being both woefully inaccurate and non linear). Because of the cooling system layout, at that temp the engine is actually much hotter in some internal areas, and as the oil is always hotter than the coolant (even though the engine uses a oil to water heat exchanger).

Changing to a 160F stat tends to lower the steady state coolant temp to around 175F, and more critically lowers the oil temps by over 25F, which the oil likes much better (UOA's before and after have shown the oil actually shows better parameters for longer distances between changes with the 160F stat). And on a base car, adding both the 160F stat and the "S" oil cooler (nearly twice the capacity of the base unit) improves the oil life even more. In essence, lowering the coolant and oil temps translates into improved life for both the oil and the engine.

And once and for all, cars with 160F stats do not warm up more slowly; in fact, the tend to warm up more quickly as the warmed coolant starts to flow sooner, not later.

What he said, And….IF you are added an UD Pulley, the water pump will be spinning at a slower rate, so you need all the help you can get REDUCING ENGINE TEMPS. A cooler engine produces more power. All I know is, I put a low-temp thermostat in and it seems to run better, warm up quicker, and WHEN IT DOES GET REALLY HOT OUTSIDE the temp of my vehicle may go up a bit higher than normal BUT it stays UNDER the hottest temp that the higher thermostat allowed. In other words, the engine temps don't seem to get AS HOT…cooler = faster.

Sorry but that explanation was anything but fast.

Kashmir…what the heck is that swimming on your seats?

[shadrach74]

Originally Posted by JFP in PA

OK, here goes: The thermostat sets the baseline minimum operating temp for the engine; it is the temperature the engine returns to when running at a steady state (road speed air flow across the radiators). Because of the convoluted design of the M96/97 cooling system, particularly the engine passages themselves, these engine's typically run a bit hotter than the temperature at which the thermostat opens. As the result, with the OEM stat opening at 186F, it is not unusual for the engine to run 210-215F at steady state on a fully instrumented 986 (forget what the dash gauge say, they are well known for being both woefully inaccurate and non linear). Because of the cooling system layout, at that temp the engine is actually much hotter in some internal areas, and as the oil is always hotter than the coolant (even though the engine uses a oil to water heat exchanger).

Changing to a 160F stat tends to lower the steady state coolant temp to around 175F, and more critically lowers the oil temps by over 25F, which the oil likes much better (UOA's before and after have shown the oil actually shows better parameters for longer distances between changes with the 160F stat). And on a base car, adding both the 160F stat and the "S" oil cooler (nearly twice the capacity of the base unit) improves the oil life even more. In essence, lowering the coolant and oil temps translates into improved life for both the oil and the engine.

And once and for all, cars with 160F stats do not warm up more slowly; in fact, the tend to warm up more quickly as the warmed coolant starts to flow sooner, not later.

JFP,

Thank you for the explanation.
Have you instrumented the "steady state" temps you're speaking of?
Your explanation contradicts my understanding of the principles of thermo dynamics. If the car runs steady state of 210-215f with with a 186df thermostat it should run the same with 160df thermostat. Both thermostats will be wide open flowing fully. The engine produces the same amount of heat and the cooling system has the same capacity. "Turning the cooling system on sooner" should have no effect on the steady state operating temp.

As to the "once and for all" comment. I'm not talking about water temp,in the radiators, I'm talking about the block. As far as heat in the cabin, I was not aware that the thermostat controlled the flow to the heater core, that is uncommon in most cars. What i am concerned about what is important to engine longevity for cars operating in a 4 season environment, the oil temp. Adding 30df radiator coolant to an engine that has just gotten its recirculating engine coolant 160df is a recipe to slow the warm up to steady state temps... Like adding ice cubes to a pot of water that your trying to boil.

My contention all along has been that the only thing a low temp thermostat does is slow the time it takes for the engine to get to "steady state" and you've not changed my mind.

Those of you running low temp thermos: What changes are you seeing on your temperature readouts? Notoriously inaccurate or not, the gauge ought to at least be consistent in its inaccuracy (I mean there not made by Smiths or Lucas) and show a lower steady state operating temp if what JFP says is the case...even if the number is wrong.

[JFP in PA]

Originally Posted by shadrach74

JFP,

Thank you for the explanation.
Have you instrumented the "steady state" temps you're speaking of?
Your explanation contradicts my understanding of the principles of thermo dynamics. If the car runs steady state of 210-215f with with a 186df thermostat it should run the same with 160df thermostat. Both thermostats will be wide open flowing fully. The engine produces the same amount of heat and the cooling system has the same capacity. "Turning the cooling system on sooner" should have no effect on the steady state operating temp.

As to the "once and for all" comment. I'm not talking about water temp,in the radiators, I'm talking about the block. As far as heat in the cabin, I was not aware that the thermostat controlled the flow to the heater core, that is uncommon in most cars. What i am concerned about what is important to engine longevity for cars operating in a 4 season environment, the oil temp. Adding 30df radiator coolant to an engine that has just gotten its recirculating engine coolant 160df is a recipe to slow the warm up to steady state temps... Like adding ice cubes to a pot of water that your trying to boil.

My contention all along has been that the only thing a low temp thermostat does is slow the time it takes for the engine to get to "steady state" and you've not changed my mind.

Those of you running low temp thermos: What changes are you seeing on your temperature readouts? Notoriously inaccurate or not, the gauge ought to at least be consistent in its inaccuracy (I mean there not made by Smiths or Lucas) and show a lower steady state operating temp if what JFP says is the case...even if the number is wrong.

Yes, we have seen this both on cars with full instrumentation (after market coolant and oil temp gauges), but have also seen it using PID scanners as well.

The steady state I refer to is the equilibrium temperature the car settles at when running at a steady highway speed (50-60MPH) on an average day (say 68-75F air temp). I think that you are overlooking the heat transfer capacity of the cooling system in these cars, and the throttling effect of the stats; stuck in traffic, a car with a 160 stat will eventually get warm and kick the fans on, but it takes longer than with the 186 stat. Once either car gets moving, both will settle back to a steady state condition, with the 160 stat car settling at a lower temp (usually around 175F or so). This is the impact of the heat transfer capacity of the cooling system. But the car with the 186 stat settles at a much higher temp, often north of 210F. If you put both a 160 stat and an 186 stat in a beaker of heated water as I mention earlier, you would note that at around 170F the 160 stat is wide open, while the 186 stat is still closed. As the water gets hotter, eventually the 186 stat starts to open, but is not fully open until well past 200F, restricting the coolant circulation up to that point; so it is "throttling" the coolant flow. So even though the car has the capacity to transfer the heat out of the engine at steady state, the throttling of the 186 stat restricts the coolant flow and keeps the coolant hotter at the same speeds and air temps.

The inaccuracy of the dash display is actually two fold; it is inaccurate across much of its "band width", but it is also non linear (it does not "sweep" equal amounts for an equal amount of coolant temperature change). On a car showing 180 degrees on the dash, it is not unusual for a PID scanner to read 210F, yet both the scanner and the dash are getting their information from the same sensor in the engine. In essence, the temp display is little more than a "not over heating/over heating" idiot light replacement.

[pedot99boxster]

Originally Posted by JFP in PA

Yes, we have seen this both on cars with full instrumentation (after market coolant and oil temp gauges), but have also seen it using PID scanners as well.

The steady state I refer to is the equilibrium temperature the car settles at when running at a steady highway speed (50-60MPH) on an average day (say 68-75F air temp). I think that you are overlooking the heat transfer capacity of the cooling system in these cars, and the throttling effect of the stats; stuck in traffic, a car with a 160 stat will eventually get warm and kick the fans on, but it takes longer than with the 186 stat. Once either car gets moving, both will settle back to a steady state condition, with the 160 stat car settling at a lower temp (usually around 175F or so). This is the impact of the heat transfer capacity of the cooling system. But the car with the 186 stat settles at a much higher temp, often north of 210F. If you put both a 160 stat and an 186 stat in a beaker of heated water as I mention earlier, you would note that at around 170F the 160 stat is wide open, while the 186 stat is still closed. As the water gets hotter, eventually the 186 stat starts to open, but is not fully open until well past 200F, restricting the coolant circulation up to that point; so it is "throttling" the coolant flow. So even though the car has the capacity to transfer the heat out of the engine at steady state, the throttling of the 186 stat restricts the coolant flow and keeps the coolant hotter at the same speeds and air temps.

The inaccuracy of the dash display is actually two fold; it is inaccurate across much of its "band width", but it is also non linear (it does not "sweep" equal amounts for an equal amount of coolant temperature change). On a car showing 180 degrees on the dash, it is not unusual for a PID scanner to read 210F, yet both the scanner and the dash are getting their information from the same sensor in the engine. In essence, the temp display is little more than a "not over heating/over heating" idiot light replacement.

Hi, i believe my water pump on my 986 is bad, lost allot coolant last friday temp. indicator was blinking, checked underneath and suspected the water pump, there's allot of stain around the hose under the pump. pressure checked it to about 10-15 psi but no leaks visible. also noticed when the engine temp get to about 186 deg. the engine blower doesn't come on then about 200 deg. the radiator fan on both front comes on. thinking about doing this water pump and thermostat replacement on my own. did you have to remove the front engine mount to replace the water pump?
where did you get the parts?
Thanks
Ferdie

[Bryan topping]

Originally Posted by JFP in PA

OK, here goes: The thermostat sets the baseline minimum operating temp for the engine; it is the temperature the engine returns to when running at a steady state (road speed air flow across the radiators). Because of the convoluted design of the M96/97 cooling system, particularly the engine passages themselves, these engine's typically run a bit hotter than the temperature at which the thermostat opens. As the result, with the OEM stat opening at 186F, it is not unusual for the engine to run 210-215F at steady state on a fully instrumented 986 (forget what the dash gauge say, they are well known for being both woefully inaccurate and non linear). Because of the cooling system layout, at that temp the engine is actually much hotter in some internal areas, and as the oil is always hotter than the coolant (even though the engine uses a oil to water heat exchanger).

Changing to a 160F stat tends to lower the steady state coolant temp to around 175F, and more critically lowers the oil temps by over 25F, which the oil likes much better (UOA's before and after have shown the oil actually shows better parameters for longer distances between changes with the 160F stat). And on a base car, adding both the 160F stat and the "S" oil cooler (nearly twice the capacity of the base unit) improves the oil life even more. In essence, lowering the coolant and oil temps translates into improved life for both the oil and the engine.

And once and for all, cars with 160F stats do not warm up more slowly; in fact, the tend to warm up more quickly as the warmed coolant starts to flow sooner, not later.

OK, so I have a question..my car is a 2001 base...
I would like to add the center radiator, S oil inter cooler & low temp stat but can't do it all at once right now.
Would I gain much by just doing the stat & inter cooler right now and the center radiator once I get the parts for the rest pieced together?
I would flush the system & replace the coolant since I have no idea how old it is or if it's the right coolant (the stuff I have in there is green).
The car doesn't overheat or anything worrisome like that.

[kashmir]

Originally Posted by shadrach74

Good deal. Can you explain why you installed a 160df thermostat? No one (including those that sell them) has been able to give me a reasonable and scientific based answer as to why they are beneficial. Is there some advantage to having a longer warm up period?

Porsche engineers had used the hotter thermostat to help burn off water in the oil with the idea the cars would go 15,000 miles on an oil change. In my opinion that is a bad idea. The other and the main reason is the hotter engine made it easier for the car to pass U.S. emissions. If I wanted to be green I would own a Nissan Leaf.

Michael

[JFP in PA]

Originally Posted by kashmir

Porsche engineers had used the hotter thermostat to help burn off water in the oil with the idea the cars would go 15,000 miles on an oil change. In my opinion that is a bad idea. The other and the main reason is the hotter engine made it easier for the car to pass U.S. emissions. If I wanted to be green I would own a Nissan Leaf.

Michael

If burning off water was the purpose of the hotter thermostat, then running a 160F stat would show oil degradation is a used oil analysis; but in fact the oil does not show any signs of water build up and the UOA's actually indicate the oil is doing better because of the lower coolant temperatures.................

[rp17]

What did you use to purge the system of the air bubbles?

[troop1]

Originally Posted by rp17

What did you use to purge the system of the air bubbles?

the Bentley service manual provides the full coolant replacement procedures, I used these procedures when I did my water pump and low temp thermostat.

its a little long but very effective. My neighbors were probably wondering why i was revving the engine for 5 minutes.

The procedures are also on the Pelican website

[rp17]

Thanks Troop.

Originally Posted by troop1

the Bentley service manual provides the full coolant replacement procedures, I used these procedures when I did my water pump and low temp thermostat.

its a little long but very effective. My neighbors were probably wondering why i was revving the engine for 5 minutes.

The procedures are also on the Pelican website

[troop1]

Originally Posted by rp17

What did you use to purge the system of the air bubbles?

the Bentley service manual provides the full coolant replacement procedures, I used these procedures when I did my water pump and low temp thermostat.

its a little long but very effective. My neighbors were probably wondering why i was revving the engine for 5 minutes.

The procedures are also on the Pelican website

[kashmir]

Originally Posted by rp17

What did you use to purge the system of the air bubbles?

Keep the valve open that is under rubber mat of the filler let the car warm up and rev it for 5 min. Close the valve and you should be good.

[JFP in PA]

Originally Posted by rp17

What did you use to purge the system of the air bubbles?

A Uview airlift system that refills the entire system under vacuum, eliminating any chance of air pockets. Uview makes the OEM tool for Porsche, but you can buy it from them for about 1/7th what Porsche sells them for.

[Flavor 987S]

Does a 986 have a different thermostat than a 987? When I asked L&N about swapping out to the 160 thermostat I was told it was not necessary in the 987.

[JFP in PA]

Originally Posted by Flavor 987S

Does a 986 have a different thermostat than a 987? When I asked L&N about swapping out to the 160 thermostat I was told it was not necessary in the 987.

Fits up to model year 2008, does not fit 09+.

[AKnowles]

FWIW, I used the Bently method while I was flushing with distilled water. Then ordered a vacuum system for the final fill. Was much easier and had no worries about air bubbles. For the $100 I seriously recommend one. Particularly if you plan to add a third radiator as I do (just need the front hoses and one more frame bracket) or a flush and fill every couple of years.

[shadrach74]

Originally Posted by AKnowles

FWIW, I used the Bently method while I was flushing with distilled water. Then ordered a vacuum system for the final fill. Was much easier and had no worries about air bubbles. For the $100 I seriously recommend one. Particularly if you plan to add a third radiator as I do (just need the front hoses and one more frame bracket) or a flush and fill every couple of years.

This...^^^

I have one and it makes a huge difference, but you will still need to pull the coolant bleed valve and drive it for a bit.