Regular Thermostat vs. Low Temperature Thermostat?

[Timpkin]

I'm about to change the coolant in my 2000 Boxster S (986) and may as well replace the water pump for a little preventative maintenance. I was also looking at the Low Temperature Thermostat which opens up 20 degrees earlier than the regular thermostat. I've not had a heating issue but why not go above and beyond if I can, right?

Has anyone done this and recommend it? Now that I'm at 10 years on this vehicle and doing the maintenance myself, I don't mind spending a little more now so it lasts that much longer.

Thanks.

[JMatta]

I can highly recommend it; I installed one in my '02 S when they first came out and believe this is a modification everyone should consider. Repeating the facts as I know them, the factory t-stat begins to open at around 186 degrees F and is not fully open until coolant temps reach over 205 degrees! The LN stat opens at 160 degrees and is fully open before the factory t-stat even begins to open. This insures coolant temps stay (while the car is in motion) some 20 to 25 degrees cooler than stock, which translates to lower oil temperatures. Oil analysis has shown that oils breakdown at higher temps and is pretty well past useful life at 5 to 6 thousand miles.

My car runs cooler and I change my oil (Castrol Syntec 10W40) every 3000 miles, which is annually for me.

For more information, see LN Engineering Nickies The Original and Genuine CNC Billet Aluminum NSC-Plated Cylinders. This is a very inexpensive upgrade and most other factory models run low temp t-stats for the obvious benefits.

[hosickjg]

The most supported theory on the #6 cylinder failure (D-chunk) is its caused from to much heat on that back cylinder. Since #6 is the furthest cylinder from the water pump the coolant has travelled past every cylinder on the way to #6 and is to hot at that point. By installing a low temp like the one LN offers you will be reducing the risk of a very expensive D-chuck failure. I personally highly recommend the low temp for anyone with a 986 boxster.

[s_wilwerding]

We have discussed this on another board, but once the car is up to operating temperature, there is NO DIFFERENCE between having a low temp thermostat and a high temp one, once they are both open. It is radiators, not thermostats, that are responsible for coolant temperatures. The only difference is that the low temp opens sooner, which actually causes your engine to take longer to get up to operating temp, which is not necessarily a good thing.

So, it's really only the "interim" period that is different, when your coolant is between 160 and 190 degrees, and I have not seen any definitive issues that occur during that timeframe.

[JMatta]

I disagree with your statement. The stock t-stat will remain open at 205 degrees allowing full coolant flow, whereas the low temp unit allows full flow at 184 degrees; big difference in my book. That's a twenty degree difference of coolant flowing through the radiators. I suggest you and the others from the "other" board re-examine the facts.

[s_wilwerding]

Operating temperature on most Boxsters is right about the middle of the zero in 180, which translates into around 195-200 degrees. At that point, the stock thermostat is mostly open, which means that coolant is flowing, and the engine is being cooled. If you are driving on the Interstate not running the A/C and not stressing the engine, operating temperature is a little lower, but the stock thermostat is still open. I am not debating your temperature ranges - I am sure they are close to accurate.

What I am saying is that all the low temp thermostat is buying you is an extended warmup period, which may or may not be good for your engine. I have not seen a lot of evidence that engines are particularly susceptible to issues during the warmup period, so I am not clear as to the benefits of extending that period. And, as I said above, it may not be particularly good
for your engine to be below operating temperature for a longer period of time.

Not only that, but by extending the warmup period, you are not allowing your engine to get up to operating temperature on short trips. If you drive your car regularly less than 15 minutes, it is not getting warm enough to burn off a lot of the water that has accumulated in the engine and exhaust, and that has been known to cause issues.

If you are worried about coolant temps during hard driving or tracking, get a third radiator - it will make a much bigger difference than adding the low temp thermostat.

Here is the full discussion - as you can see, there are people on both sides of the argument, but people like Lauren (who is a Porsche mechanic) tend to agree with my statements.

[orcadigital]

Steve is very correct. By the reasoning that people use about using a lower temp thermostat making a car run cooler, then why put a thermostat in at all? Free flow coolant all the time.

Simplifying Steve's point, thermostats affect warmup time, not operating temp.

If you want to be preventative on engine cooling, one of the most overlooked bits is cleaning out inbetween the condensors and radiators where all kinds of junk manages to get stuck. Its pretty easy to do as well.

[JMatta]

The stock t-stat will restrict coolant flow when not fully open; in other words, it forces the coolant temperature to remain at the high 205 to 210 degree level. The low temp t-stat will remain fully open at temperatures as low as 184 degrees and not allow the temps to rise into the 200 degree range, unless the radiators are full or debris or the car is sitting in traffic with no airflow or fans running on the radiators.

I don't see your logic in why you think they are the same after warm-up?

[orcadigital]

This is just going to turn into another Oil or MM debate. The assumption Steve and I are making is that the vehicle runs hot enough that both thermostats will be open and cycling coolant through the radiators at operating temperature, and open = open. Internal head temps are approximately 300 degrees, maybe more, but well over that of the thermostats. One the engine temp is there (by vitrue of combustion), you should be flowing coolant all the time, depending on how efficient the heat transfer is from the block to the coolant. You are flowing the same temperature coolant through the system though, as both thermostats are open.

If you want to cool more, then you need to increase your cooling capability. At the very minimum if you are flowing coolant through the radiators at lower temps, then you need a lower temp fan switch to turn on the fans sooner, otherwise you are getting little cooling efficiency, expecially at low speeds where the extra cooling would be more warranted.

[mcmike27]

Our 98 986 has 91k miles on it and this past spring I did a preemptive stirke and replaced the W/P. Along with the coolant swap I personally decided on the 160 deg t-stat. I would agree that it does in cooler weather warm up a bit slower it has helped with the blistering hot summer here in the NE this year. The other item I swaped out was the stock smaller oil cooler unit for the the 'bigger' 'S' type unit. I was able to buy one from DC Automotive used for under $100.00 that along with the new W/P the 160 deg t-stat have helped considerably with cooling this summer. Somewhere down the line I may opt for the 3rd rad but that is another project for another time. I would VERY VERY much suggest that at least once every 2 years you take off the front bumper and CLEAN out the junk that gets lodged between the A/C condensers and the rad's in the front bumbers and every year use a shop vac with a long hose attachment and vaccum all the loose debris and then hose it all out to clear out the dust.

Better cool motoring!

m2

[racer]

Another way to consider is the factory could have put any temp thermostat on the car.. They chose the one they did for a reason. I understand we all have access to tons more data than the factory so it would make sense to replace it with one not specified for the car

[JMatta]

The factory did such a good job engineering the M96 platform, we should just forget the high number of engine failures and go blindly forward.

It's your car...believe as you wish.

[dad911]

I haven't tried it in my Boxster yet, but Water Wetter reduced (peak) temps at the track in my 944 turbo.

In the boxster I'm going with center radiator and a turbo'S' oil cooler.

[s_wilwerding]

Well, I talked with an automotive expert this evening, and I will admit that I was wrong - he said that an engine will run at about the temperature of the thermostat installed - if you install a lower temp thermostat, the engine will tend to run at a lower temperature.

However, he said that he would not recommend running engines at lower temperatures for a number of reasons. First, he said that modern engines are designed to run around 200 degrees - they are built such that the thermal expansion at that temperature is taken into account. If they run at lower temperature, they run richer, which hurts fuel economy and emissions. Also, he said most modern oils are made to run around 200 degrees - he said that most oils, until they get up to operating temperature, are somewhat thinner - they tend to collect water and gas, which is present until they get burned off at around 200 degrees. He said the major reason that engines have sludge issues is when they are run cooler than what they are designed to.

So, yes, you are correct that your engine runs cooler. However, the downsides are not worth it to me, as I would much rather run it as Porsche designed it and risk the small possibility of heat-related issues, rather than run it cooler, richer, and with the threat of sludging.

[dad911]

Steve, that may be under normal conditions where the radiators are sized large enough to keep the temps down. The thermostat regulates the temp.

Hot day, on the track.... definitely runs hotter than the thermostat. Those are the conditions when we try to improve cooling. I don't think a lower thermostat will help there.... ask your 'expert'

[orcadigital]

Can't speak for "before", as I haven't had the car that long, but I added a bottle of the Royal Purple Coolant Additive (Water Wetter if you will) and at Roebling Road, I was boiling brake fluid and the coolant temp was rock solid. Day was high 90's, heat index was 112. Was quite pleased. I did notice the same in my old 944 turbo as well, but it was a daily, so it was traffic where I noticed it.

Originally Posted by dad911

I haven't tried it in my Boxster yet, but Water Wetter reduced (peak) temps at the track in my 944 turbo.

In the boxster I'm going with center radiator and a turbo'S' oil cooler.

[s_wilwerding]

Originally Posted by dad911

Steve, that may be under normal conditions where the radiators are sized large enough to keep the temps down. The thermostat regulates the temp.

Hot day, on the track.... definitely runs hotter than the thermostat. Those are the conditions when we try to improve cooling. I don't think a lower thermostat will help there.... ask your 'expert'

I completely agree - my statement only referred to "normal" conditions - if you're running warmer than normal, it makes no difference which thermostat you have. As was stated above, if you're warm enough where the stock thermostat is open, it makes no difference.

[JMatta]

I agree the lower temps will not burn off the water and fuel collected in the oil (the M96 lends itself to fuel contamination) which is why LN Engineering recommends using a higher quality oil than the factory fill and changing more frequently in the 5 to 6 thousand mile range.

PCA Chicago Region is very fortunate to have Charles Navarro of LN within our region and readily available for M96 engine discussions. I don't wish to "parrot" his remarks, but the data he and Jake Raby have collected over the years speak volumes to the issues these engines have. I wish to keep mine healthy and have made a number of changes over the years to protect my investment.

BTW, I'm glad to see participation on the Pelican Forum...Wayne has been good to us and I know he's trying to build an active community here.

[orcadigital]

Jake Raby is not too far north of me, and I am planning on running up there when my clutch gets low to do the IMS retrofit at the same time. While my Box is an early model, it also has a factory replacement engine, so I am not as worried about it.

The car has been rock solid for me though, so no complaints to date.

[mikefocke]

I hear tell it isn't a simple matter any more of "running up there" as he has a months long waiting list especially during the winter months where folks from up North want to ship their cars to him and get them back for the warmer months.

Make your appointments early....