dennis hiip

I'm now making plans for the LN IMS bearing replacement. At the same time, I'll change out the AOS. The PO just replaced the clutch but not the IMS. Car now has 78K. Being the worrywart that I am and as I continue to read about potential 996 engine failure, I'm wondering if the low temp thermostat is also head/cylinder crack preventive or mainly for performance increase. Seems like lower temp. makes sense. The LN website doesn't make definitive statement regarding prevention. Ive had my 2003 for a little over a month.

ivangene

LOTS of talk about this one...I for one am right in the middle... the idea sounds OK but I am not convinced without increasing the capacity of the system you can avoid a saturatioon point that is the same with or without it, that said if I was swapping water pumps I would probably put it in

fpb111

Probably not much. However it is interesting to see that 997s run 10 deg lower temp on the gauge. Do they have a lower temp T-stat?

soverystout

First off, I have not purchased the low temp thermostat. I am interested in what Jake has to say.

I mentioned it to my indie and he said that a low temp stat will ruin your gas mileage and foul out the cats. The LN site does adress these issues i believe.

Jake has mentioned before that when he finds a cracked head that many times he finds pieces of water pump impeller or RTV gasket sealer that has traveled into the head, creating a hot spot, which eventually can lead to a crack.

So I can understand why the LN site would not come out and say "this thermostat will prevent cracked heads". Making a statement like that is inappropriate, untrue, and it does not seem to be Jake's style.

So with that said, you may want to replace your water pump, don't use sealant, and swap out the coolant and replace it with Porsche spec coolant.

Chris996

"101 Projects for Your Porsche Boxster " had a nice write up about this.

http://www.pelicanparts.com/techarti...t_and_Pump.htm

" The factory thermostat starts to open at about 187° F (86° C) and only fully opens at almost 210° F (99° C). This means that the engine needs to get very hot before it starts sending its coolant to the front radiators. For this reason, I recommend installing a low temperature thermostat in place of the factory one. LN Engineering has developed a thermostat that starts opening at 160° F (71° C) and is fully open at about 180° F (82° C). Lower coolant temperatures translate into lower oil temperatures, and the dyno tests that LN Engineering has performed on the cars with the low-temp thermostat installed have revealed a small increase in HP (typically about 5HP). It is my guess that Porsche designed the thermostat to open a bit later in order to help the cars run a bit hotter, which typically helps with emissions testing and the burning off of water out of the oil, which can then lead to longer oil change intervals. Installing the low-temp thermostat is a smart idea for engine longevity: it's available for about $175 from PelicanParts.com."

Byprodriver

Yes it helps, Turbo's have a 180 stat to help control temp spikes.

LVDell

I can't imagine that 210 is bad for these cars. Overheat it? Of course it's bad, but 210 is not overheating. And if you run the car too cold don't you risk not being able to burn off the contaminants in the coolant and oil thus REDUCING engine life?

Hopefully the smarter guys will chime in........

Dharn55

One the issues with the thermostats and coolant temps is where the temps are being measured. The thermostat opens where the coolant is returning to the water pump after circulating through the engine, and more importantly after circulating through the radiators thus after it has been cooled to the lowest temp it is going to be in the system. What this means is that if the temp of the water is 187 degrees when it hits the thermostat ( and the thermostat starts to open) it logically was significantly hotter when it left the engine before it went through the radiators. And if the coolant is 210 degrees at the thermostat (to fully open the thermostat) what temp is it at when it leaves the engine/before it gets to the radiators. Again it must be significantly hotter than 210 degrees for the coolant to be 210 degrees after it passes through the radiators and returns to the thermostat.

The bottom line is that the coolant exiting the engine is hotter than it is at the thermostat. I don't know what the temp drop is when the coolant passes through properly operating radiators, and it will vary based on ambient temps and airflow, but I would guess 20 or more degrees, maybe much more (perhaps someone can chime in here). So if the water at the thermostat is 210 degrees for a fully open thermostat, then the water exiting the engine may be 230, 240 250+ degrees.

Based on these assumptions, a thermostat that starts to open at 160 degrees and is fully open at 180 degrees should mean that the coolant exiting the engine is is the low 200's.

Here is a link to an interesting article by Hartech that touches on this subject.

http://www.hartech.org/docs/buyers%2...20part%205.pdf

Something to note in the article is the balancing of coolant flows in the engines. In the 3.4 VarioCam engines the head gaskets were used to control/balance the flow of coolant, with more coolant to the hotter areas and vice versa. This was done by having different size openings in the gaskets, and different gaskets for each head. In the 3.6 VarioCamPlus engines Porsche changed this, the openings are all the same size and the head gaskets are interchangeable. Hartech seems to say that this has caused hot spots and some problems in the later engines. Interesting!

Shark Attack

My car does run slightly cooler with this thermostat

Flat6 Innovations

The cracked head issues occur with engines running normal temperatures.. Lots of times the cracks stem from some other failure and the crack is actual collateral damage.

I'd like to tell you that the LN Thermostat would prevent a crack, but thats a sense of security that doesn't exist. You can crack a cylinder head with coolant temperatures below normal, because the cracks stem from weak castings and blocked cooling capillaries/ passages.