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Old 06-26-2011, 03:35 PM   #1
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Low Temp Thermostat

Well, having successfully done the front wheel bearing replacement, I had just a week to fully enjoy the Box and the nice weather...but then the inevitable occurred. With 57K on the odometer, I had expected that it might happen, though I had planned on addressing this in a preventative maintenance fashion prior to actual failure.

What was it that went, you might ask? Well, it was the water pump. I started, day before yesterday, to smell something hot after a drive. Nothing too drastic...smelled like someone had left a hot iron on a T-shirt a little too long. Then yesterday, went for a drive (to, amongst other missions, push 'whatever' a little closer to failure, to aid in diagnosis). Could hear a vague clattering or whining sound from behind me when I sat at idle and blipped the throttle. Got home, looked under the car, saw a few drops hittin' the driveway. Pulled forward a few feet to look...it's coolant. I'm pretty much thinking w/p at this point.

Removed the engine cover inside the car and the belt, while largely intact, had started to peel off into a few thin strands. Removed the belt. Everything turns fine (pulley-wise), but there is some wobble to the w/p wheel. So, I think I got my diagnosis.

I know this has been talked about ad nauseum, but I'm still wondering about the low temp thermostat. I've had one or two (un-named) sources suggesting that the switch isn't really particularly necessary. From the threads I've read (here, largely) many suggest the switch as a good thing, and a few say, while it may not be necessary, switching to a low temp t-stat can't hurt. Cost, to some extent, is an issue.

My question: Is there anybody out there who'd argue AGAINST switching to a low temp t-stat? If so, what's your reasoning?

My second question: I plan on doing the front motor mount at the same time. While it may become obvious as I proceed, I'm wondering whether it makes more sense to do the water pump (+/- the thermostat) first or to do the motor mount first?

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Old 06-26-2011, 06:32 PM   #2
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Ok, I'll try. Low temp thermostat just delays car getting to operating temp, which prevents burn off of condensation in the crankcase. Water, according to LN engineering's website, drastically reduces IMS bearing life. But at the same time, since they make the low temp thermostat, they also say that lower operating temps prolong IMS life. So I don't know. Do a search, its been hotly debated before.

FWIW, I just did the waterpump and just replaced ithe thermostat with the stock part. After cleaing the radiators, it runs in the 93-100C range in 90+ (F) weather in stop and go traffic. I don't see this as a problem.
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Old 06-26-2011, 09:09 PM   #3
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Does anybody sell a low temp stat as just the stat ? I'd like to change mine, but $170+ is kind of steep for a $20-$40 part.
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Old 06-27-2011, 12:32 AM   #4
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Listening to the experts, removing the engine mount first makes the water pump installation much easier. Thr thermostat installation is very easy as a stand alone item.
I think you have to delve a little deeper than just looking at lowering coolant temperatures during (normal) driving...
The oil temperatures in the M96 engine very quickly follow, and then exceed, the coolant temperatures, and having oil temps well above 100 deg C (220 F) in my book does no good for engine longevity. I realise that driving in heavy traffic won't make the slightest difference whether or not you have a low temp T'stat, but if I can keep my oil within a reasonable temperature zone its got to be a plus...
As for the cost from LN Eng. or Flat 6, the T'stat already comes mounted in a new housing so you don't have to get the special tool to remove the original T'stat and then refit the new one into the old housing.
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Old 06-27-2011, 02:47 AM   #5
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Steve-how much lower is the temp with the LN thermostat?
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Old 06-27-2011, 06:42 AM   #6
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The low temp t-stat will allow the coolant to run 20-25 degrees cooler than the stock part, which lowers oil temps...a good thing in my book. The stock unit doesn't begin to open until the coolant temps reach around 186 degrees and is fully open at around 210, where the low temp opens at 160 and is fully open at 185. I've had mine for two summers now and the car runs much cooler.

http://www.lnengineering.com/lowtemperaturethermostat.html
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Old 06-27-2011, 10:26 PM   #7
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it may cause more problems than it cures if you have a late model vehicle. Before emission controls and computerised engine controls came.









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Old 06-28-2011, 04:16 AM   #8
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i have the low temp thermostat. LN does sell just the insert; it's $100. the car runs a little cooler with it in place, but the main thing i notice is that the temp is stable. it used to fluctuate a lot over about a 20deg range while i drove. now, the thermostat is fully open at operating temp, so everything seems a bit more steady.

i know this does virtually nothing once we're into the higher temp range, but it DOES get the coolant fully circulating a lot sooner, which makes for a more even temp across the engine mass. apparently hot spots can be an issue with these motors.
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Old 06-28-2011, 08:15 AM   #9
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How's the waterpump affected by low temp thermostat?
Won't make water pump run faster/harder? Will it contribute to shorter waterpump life?

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Old 06-28-2011, 08:32 AM   #10
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Quote:
Originally Posted by sasha055
How's the waterpump affected by low temp thermostat?
Won't make water pump run faster/harder? Will it contribute to shorter waterpump life?

if anything, i would think it would INCREASE water pump life. the pump is always spinning no matter what, but if the OEM thermostat is partially closed under normal driving conditions, the pump is working harder (higher local pressure) trying to push fluid through a smaller hole.

the pump won't run faster since its speed is proportional to the crankshsaft speed.
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Old 06-28-2011, 09:04 AM   #11
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Thanks insite,

Time to get a waterpump and thermostat insert...
I was planning to spend those money on new rear tires.. but I gues, tires will have to wait

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Old 06-28-2011, 10:53 AM   #12
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Quote:
Originally Posted by san rensho
Ok, I'll try. Low temp thermostat just delays car getting to operating temp, which prevents burn off of condensation in the crankcase. Water, according to LN engineering's website, drastically reduces IMS bearing life. But at the same time, since they make the low temp thermostat, they also say that lower operating temps prolong IMS life. So I don't know. Do a search, its been hotly debated before.
Actually, that is not true. Any given engine and cooling system set up is going to heat up at the same rate, regardless of the temperature the thermostat opens at; the only thing that changes is when the coolant begins to circulate, and the "steady state" temp the engine coolant ultimately reaches.

As for burning off water of fuel contamination in the oil, an engine with the 160 degree stat gets the oil more than hot enough to take care of that. Literally dozens of before and after UoA's show no change in the level of contamination in the oil, but at the same time show the oil is holding up better with the lower temp stat......
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Old 06-28-2011, 10:58 AM   #13
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Quote:
Originally Posted by miclebarbossa
it may cause more problems than it cures if you have a late model vehicle. Before emission controls and computerised engine controls came.
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Also not correct. We have more customers running the 160 degree stat than I care to count, every one has to pass state mandated inspection testing, some even get subjected to "sniffer" probes (local requirement). After multiple inspection cycles, none have failed. Part of the reason is the DME mapping in the M96/97 is more than capable of adjusting for this change.
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Old 06-29-2011, 07:45 AM   #14
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I just had the WP, 160 T-stat, motor mount, pulleys, and belt replaced. Eyeball indications are that the car runs a bit cooler around town and during a DE track day. I don't see a down side to this.
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Old 06-29-2011, 07:56 AM   #15
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So if the low temp thermostat works so well why won't Porsche put it in all their cars?

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Old 06-29-2011, 10:29 AM   #16
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They do, the same temp stat is in the Turbo, GT2 and GT3 cars, the cars they want maximum power from.
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Old 06-29-2011, 01:54 PM   #17
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why won't Porsche put it in all their cars?

I think they got their buyer audience predictions wrong...assumed chicks and little old ladies would be puttering around town, instead of enthusiasts

Doesn't fit the profile of all the Boxster owners I know...
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Old 06-29-2011, 09:00 PM   #18
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I recently replaced my water pump with stock, the thermostat with LN Eng, front engine mount with stock, and the oil cooler with the "S" model. I found the water pump much easier to do with the engine mount out and the engine dropped down a bit. As I was changing the coolant too, the hoses were also dropped and out of the way, giving a lot better access.

As a side note, I managed to get my torque wrench on every bolt except one of the horizontal motor mount bolts.

I know the temp gauge isn't the best source of info, but it says the engine does run a little cooler.
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Old 06-30-2011, 05:18 AM   #19
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Hey, Clickman: I approve of your Goal in Life...I've thought the very same thought with my dog!
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Old 06-30-2011, 03:41 PM   #20
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"So if the low temp thermostat works so well why won't Porsche put it in all their cars?"

There are two reasons why Porsche installs a standard temp thermostat:

(1) Lower Emissions - the quicker that an engine warms up, the lower the emissions.
(2) Longer Oil Change Intervals - a warmer running engine ensures that moisture gets cooked out of the oil even on shorter trips. This allows Porsche to recommend longer oil change intervals and fewer oil changes uses less oil, reduces maintanence costs, and is considered to be "greener" for the environment.

The above statements are generally true for almost all car manufacturers in this day and age.

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