Why I installed a low temp thermostat.

[bar10dah]

I'm fast approaching 75K miles. A mileage where some say is a good time to change out the water pump as preventive maintenance.

I'm leaning towards the 160F Wahler. How difficult is it to use the specialized tool to replace the thermostat into the original cover? Is it worth the trouble to save a few bucks? Seems to be only about $6. Or just get the thermostat/cover already put together?

UPDATE: Disregard. I was looking at the wrong listing. Appears fro Pelican, $70 for all three pieces; thermostat, cover, gasket. $69.50 for just the thermostat insert...

[kotto]

Originally Posted by bar10dah

I'm fast approaching 75K miles. A mileage where some say is a good time to change out the water pump as preventive maintenance.

I'm leaning towards the 160F Wahler. How difficult is it to use the specialized tool to replace the cleaning thermostat into the original cover? Is it worth the trouble to save a few bucks? Seems to be only about $6. Or just get the thermostat/cover already put together?

UPDATE: Disregard. I was looking at the wrong listing. Appears fro Pelican, $70 for all three pieces; thermostat, cover, gasket. $69.50 for just the thermostat insert...

Where did you see the listing? I myself am looking at grabbing a thermostat to somehow increase something with my car. Anyway, I think it would be best if the dealers are to install it for you.

[tranceatlantic]

I installed the LN low temp thermostat a few weeks ago. I noticed that the temp gauge seem to sit at the lower temperature for a while but then eventually moves back up to its previous normal temperature position (needle approx vertical on a 1999 986). I figured this was because once the thermostat is wide open the final running temperature will be dependent on the radiator design/size etc.

One word of warning though. If you do a coolant flush don't park your car on an inclined driveway with the back end point down the hill. The air vent for the system is at the rear but the radiator is at the front. I had an air bubble in my radiator, went auto-crossing and blew my boiled coolant all over the place. For those of you without PhDs in physics; air goes up.

[Bala]

Originally Posted by bar10dah

I'm fast approaching 75K miles. A mileage where some say is a good time to change out the water pump as preventive maintenance.

I'm leaning towards the 160F Wahler. How difficult is it to use the specialized tool to replace the thermostat into the original cover? Is it worth the trouble to save a few bucks? Seems to be only about $6. Or just get the thermostat/cover already put together?

UPDATE: Disregard. I was looking at the wrong listing. Appears fro Pelican, $70 for all three pieces; thermostat, cover, gasket. $69.50 for just the thermostat insert...

I installed the Wahler bought from Pelican. Absolutely no difference in engine temp between stock and the low temp one. Installation was a pretty simple tho.

[coolbreeze551]

Originally Posted by Bala

I installed the Wahler bought from Pelican. Absolutely no difference in engine temp between stock and the low temp one. Installation was a pretty simple tho.

I found the same thing ... What is up with that?

[Chuck W.]

Originally Posted by Bala

I installed the Wahler bought from Pelican. Absolutely no difference in engine temp between stock and the low temp one. Installation was a pretty simple tho.

Originally Posted by coolbreeze551

I found the same thing ... What is up with that?

Can someone answer this? TIA.

[Jaak]

It seems the T-stat opens earlier to get the coolant flowing earlier, that's all it does.

Nothing else changes with the temp as the car still generates the same amount of heat as before. The temp gague is slow to change unlike the ones the 944's have and show's an average over a short time span. My old 951 used to move up and down all the time ...

[Meir]

The key to the question has to do with the somewhat strange cooling system in these engines. I'm sure someone can explain it better then me, but as far as I understand, the temp sensor is located at the return from the rediators (I think you can fined the full explanation in earlier posts in this tread). There are parts of the engine (around cylinder 6 if I remember correctly) that are much hotter than what you see on the gage. So even thogh the gage show same readings, the engine itself runs much cooler.
That's more or less what I understood before I got main

[pothole]

Originally Posted by Chuck W.

Can someone answer this? TIA.

I think people are looking at buffered gauges that won't show any changes unless they are very dramatic.

You need to be looking at the temp via either the aircon screen hack or better still via the OBD port.

The lower temp stat will make a difference to the normal operating temp as when the car is cruising at speed, it's the stat that determines the operating temp, if you had no stat at all the capacity of the rads to cool would lower the temps quite a bit at a constant cruise at say 60mph.

What I'm not clear on is why the stat would help keep things cool when the car is under heavy load etc. Once the stock stat is fully open (which happens at a much lower temp than when the car is heavily stressed in any case), there's no difference between the two stats. They are both just open.

And as far as I can tell, the reason to have the low temp stat is not reduce the temps at a constant cruise. It's to stop the coolant getting really, really hot. And it's not going to do that as both stats are full open long before the temps get really hot.

[JFP in PA]

Originally Posted by pothole

And as far as I can tell, the reason to have the low temp stat is not reduce the temps at a constant cruise. It's to stop the coolant getting really, really hot. And it's not going to do that as both stats are full open long before the temps get really hot.

The stat set the minimum or baseline coolant temperature the car is going to run at and return to when cooling off from a higher temp like when stuck in traffic. Because the stat consistently lowers the baseline temp of the coolant, it also lowers the oil temps as well, which is even more important.

As for why people don't see much movement in the dash gauge when using one, that is simply due to the grossly inaccurate and non linear nature of factory gauge, which is little more than an idiot light with a pointer.

[pothole]

Originally Posted by JFP in PA

The stat set the minimum or baseline coolant temperature the car is going to run at and return to when cooling off from a higher temp like when stuck in traffic. Because the stat consistently lowers the baseline temp of the coolant, it also lowers the oil temps as well, which is even more important.

Sorry, I can't see how you are correct.

Let's say you're stuck in traffic crawling for an hour. Essentially no natural airflow over the rads.

The low-temp stat car will start off at a lower temp. I agree on that. But pretty quickly, the coolant temp will rise to that of the full-open temp of the standard stat. That will happen within about five mins of sitting in traffic. From there on in (again, in this stuck-in-traffic scenario), you have a cooling solution that will operate just like the standard car.

Of course, in that five minutes, the standard car will have gotten hotter. And it will be first to trigger the fans. But once the low-temp stat car has triggered its fans, both cars will just cycle their fans on and off.

For the low temp stat to reduce coolant temps in this scenario, you would have to lower the trigger and shut-down temps for the fans. But these are higher than the full-open temps for the standard stat, much less the low temp stat. So, in both cars, you are cycling the fans with the stats full open.

Thus, the oil temp in the low-temp stat car will start a bit lower than the standard car, but it will quickly catch up.

[kjc2050]

Originally Posted by pothole

I think people are looking at buffered gauges that won't show any changes unless they are very dramatic.

You need to be looking at the temp via either the aircon screen hack or better still via the OBD port.

The lower temp stat will make a difference to the normal operating temp as when the car is cruising at speed, it's the stat that determines the operating temp, if you had no stat at all the capacity of the rads to cool would lower the temps quite a bit at a constant cruise at say 60mph.

What I'm not clear on is why the stat would help keep things cool when the car is under heavy load etc. Once the stock stat is fully open (which happens at a much lower temp than when the car is heavily stressed in any case), there's no difference between the two stats. They are both just open.

And as far as I can tell, the reason to have the low temp stat is not reduce the temps at a constant cruise. It's to stop the coolant getting really, really hot. And it's not going to do that as both stats are full open long before the temps get really hot.

I forgot to mention in my post: I was using the diagnostic capability of the HVAC control unit (http://986forum.com/forums/276491-post24.html) to get the temps. As for your other point, I used to think the same thing - "what difference would it make when the system is fully up to operating temp - both thermostats would be fully open" - but I don't believe that's the case. This is from Dempsey:

The factory thermostat starts to open at about 187° F (86° C) and only fully opens at almost 210° F (99° C).

Here's a link to the full article:

Pelican Technical Article: Boxster Water Pump & Boxster Thermostat Replacement - 986 / 987

If this is true, it accounts for the lower operating temps: the low temp tstat is opening earlier, and is wide open when the system is at "normal," fully-warmed-up temps; the standard thermostat is (likely) only partly open at that point.