Low Temp Thermostat - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Frodo · 06-26-2011, 03:35 PM

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?

san rensho · 06-26-2011, 06:32 PM

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.

Idaho Red Rocket 3 · 06-26-2011, 09:09 PM

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.

Steve Tinker · 06-27-2011, 12:32 AM

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.

san rensho · 06-27-2011, 02:47 AM

Steve-how much lower is the temp with the LN thermostat?

jmatta · 06-27-2011, 06:42 AM

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

JFP in PA · 06-28-2011, 10:53 AM

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......