Installed water pump and 160 thermostat today
 

Just in time for the dallas summer. http://986forum.com/forums/uploads01...1369951531.jpg

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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?

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

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? :p

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+.

986 Bentley service manual
 

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

installed water pump and 160 thermostat today
 

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

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.

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.

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.

I think the part you are missing is that a thermostat does not just run fully open, it's the device that actually controls your coolant flow and engine temperature. Otherwise, in winter our engines would never get up to operating temperature. If they operated as you state, with the heat input and cooling capacity in equilibrium, the temps. would be all over the place with varying engine load (heat input), and ambient temperature (cooling capacity). If a car wasn't designed with excess cooling capacity, it would overheat any time conditions aren't ideal.

This is absolutely right. The thermostat controls the lower temperature of the engine when the radiator cooling capacity is sufficient to keep it there. What I didn't quite appreciate is that the steady state temperature is about 15degs higher than the marked stat temp, which means it is already starting to close at 15-20 deg above marked, and regulating the flow. What no one is pointing out here is that the high temperature of the engine is regulated by the cycling of the cooling fans when the air flow is not sufficient.

For me, I am often not driving at a steady fast clip, LA traffic, city streets etc, so I would only really see the benefit of a lowT stat when cruising on the highway. I assume this situation to be true for many folks.

Out of curiosity, when pushing one of these cars on a track, > 100mph, (never done it) do you see elevated temperatures, or is there enough airflow to keep it pegged at the stat determined temperature?

You make my point with the comment "The thermostat controls the lower temperature of the engine." That is its exact function. Most cars normal operating temp is slight above that of the factory installed thermostat. Meaning that it is open under normal driving conditions additional cooling beyond is provided by air over the radiators whether it be from forward motion, or the fans.

If anyone here is suggesting that my stock thermostat does not run wide open during the spring and summer then please tell my fans to stop coming on to cool all the hot water running through the radiator.

High temp thermos are common snake oil sold to the ricer crowd as well. The whole point of the thermo is to minimize warm up time. Lowering the temp that the thermostat opens is counter to that objective. And Homeboy while I truly admire your enthusiasm, you are deluding yourself if you believe it gives you even an inkling of additional power. It will do jack $hit to cool incoming air and have no effect on the combustion event. Do not believe everything that people market to you.

I'll submit it again if anyone can provide instrumented data showing that a stock porsche thermo remains closed while the there is water in the system that is well above 186df, then by all means produce it.

If in fact the steady state temps are in the 215 to 220 range for this vehicle then the issue is with the capacity of the system and no thermostat is going to change that.

A fool and his money...

Thanks Troop.

The OEM stat is rated to start to open at 186F; you can prove it for your self, just take an OEM stat and suspend it in a beaker of water with a thermometer in it, apply heat, and watch what temp it starts to opens at (186F), and what temp it is fully open at, which is much higher.............

The 215F+ running temps are real, try hooking a scanner with PID capability up to the car and take it for a ride, you just might be surprised at how hot it gets....... Then repeat the same test on a car with the 160F stat and see what you get; the "proof is in the pudding"..........

I believe we are all in complete agreement. When running the car on a hot day in traffic with the fans cycling, both stats have got to be wide open making no difference. I would like to see how much lower mine would be in that intermediate range when the temps are not bottoming out like on the highway, but not high enough for the fans to be needed. It sounds like the low T stat in that case would be providing more coolant flow.

What I would really like to see is a curve of flow rate vs temperature for the two stats. That would settle it for me!

Here they claim that engine wear is worse at low temperature, hence a low T stat could be detrimental for cool low load highway runs.

Low Temp Thermostats: What’s the Advantage? | Tuner University

I have no basis for an opinion on this matter. JFP, it sounds like you do. Whats the tradeoff here?

Started a new thread with a poll to continue the discussion in tech. Sorry for the hijack Kashmir!