Lubrecon

After reading the Hartech Buyer's Guide, part 5, that discusses the reason behind cylinder scoring and possible methods to mitigate this from happening in the .6 and .8 engines, I am interested if any here have replaced their thermostats with the lower opening temperature thermostat as recommended by Hartech?

It seems to be a relative easy thing to do, except for the air bleeding that has to be done according to Hartech. I don't know what that would cost, but it looks like cheap insurance against a scored cylinder and the commensurate headaches of this happening as was posted today.

cbzzoom

I know a lot of people with Boxsters/996's have done it.

In the US the main advocate of the low temp thermostat is Jake Raby :

http://www.lnengineering.com/lowtemp...hermostat.html

I was a little skeptical of the low temp thermostat at first, because it seems the issue is with the *top end* temperature, not when cooling starts. If that was true, then you would want to improve the cooling capacity (eg. radiators) not the thermostat. I know many people have been skeptical because of this reasoning.

Some more details have now come out from Baz that are filling in the picture a bit better.

First of all, it's important to know that the coolant temp gauge in the 996/997 is not accurate. It has a large dead zone and shows 175 or 180 on your car even when the coolant temp is actually 200-210.

Second, the stock thermostat only starts to open at 186 and doesn't fully open until 205-210. It takes some time for the coolant to get flowing fully.

Third, even when the thermostat measures 205, which might be an acceptable operating temperature, there are spots in the engine where it is much higher.

When these issues work together, the result is (once in a while, very rarely) catastrophic local overheating. For example, if your car is running at low temp and you jump on the throttle and start thrashing it, the thermostat may still be closed and coolant is not fully flowing, suddenly part of the engine heats up very fast and before the coolant system gets up to full capacity that part of the engine is above operating temperature range. The high temp makes the oil too thin, which leads to the piston seizing or cylinder scoring problem.

The goal of the low temp thermostat is not to lower your operating temperature from 180 to 160 - it's to lower that internal hot spot from 220 to 200.

I'm not convinced that the low temp thermostat is the right solution, but there is some logic to it.

IMO as always the best solution is to treat you car well :

Change the oil often
Make sure your cooling system is healthy
Let it warm up gently before thrashing it
Run at high RPM when you are driving it hard (no big throttle at low RPM)

Lubrecon

Seems like Raby and Hartech are of the same conclusion with respect to thermostat opening temps.

cbzzoom

Small correction : LNE is Charles Navarro, but Jake is the main distributor and is an advocate of the low temp thermostat.

I don't think this issue should be overstated. This failure is rare, and the low temp thermometer is only a theoretical fix at this point. It's certainly not something I would do as a preventative measure because it requires changing the coolant.

If for some reason you have your coolant out, it might be a good idea to do then (and maybe do 3rd radiator then too).

Some relevant links :

https://rennlist.com/forums/996-foru...mostat-12.html

http://forums.pelicanparts.com/boxst...hermostat.html

http://986forum.com/forums/printthread.php?t=21905

http://www.planet-9.com/cayman-boxst...hermostat.html

Another note : you can get accurate coolant temperature on the OBDII port and display it with something like a ScanGauge. Some of the guys in the above links have done this.

Palmbeacher

...and those people are correct. Others who are credulous as to the function of an automotive thermostat are conned into buying yet another snake-oil fix for a problem created by the exploitation of internet hysteria for entrepreneurial gain.

Ray S

I just made this change (just this week) on my 996 (3.6). Frankly I was not expecting a big change in engine temp, but it really decreases the operating temp.

I'm very happy with the mod.

Ray S

Say what you want, but the results speak for themselves.

cbzzoom

Yeah, it's been pretty clearly demonstrated by actual data that the low temp thermo does in fact lower operating temperature. This seems to confirm that the two radiators do in fact have plenty of cooling capacity (under normal conditions).

I believe there are two questions you can ask that I haven't seen definite answers to :

1. What situations exactly cause the local overheating that lead to damage? Is it situations in which the two radiators' cooling capacity is not sufficient? If so, then the low temp thermo would help with normal operating temperature but not with the extreme case that actually causes the damage.

2. Are there negative side effects to running the engine cooler? Certainly emissions will be slightly worse (that's why modern engines are run so hot), but is there anything else? I've seen people suggest that an engine which has been run at 205 F for all its life will be "used to" that temp, and if you suddenly start running it at 185 F, the metals will all be slightly smaller which will affect seals and so on; I have no idea if there is credibility to this argument or not.

I know that Baz and Jake both recommend putting the low temp thermo in new engines that they rebuild, and they have almost zero financial incentive to recommend that if they don't believe in it. Hartech doesn't even sell the part (the way LNE does) - it's not like they're trying to push it on people to make a buck.

Ray S

So, I'm to believe that any company with a profit motive is somehow evil? Nobody "pushed" me to install the product, I heard about it and I made a purchase decision.

As I said based on my experience (short as it is) it has reduced the operating temp on my car. I live in NC and it gets pretty hot down here and my two Porsche's run hotter here than when I lived in Chicago.

So as far as I'm concerned this will be a good change. If you have questions give these guys a call.

http://www.lnengineering.com/

I'm happy with the product.

gpjli2

Note: Normally at high temps the cooling fans are triggered. According to LN's advert (pg 2) under conditions of low speed/stop and go driving, etc, there will not be sufficient air flow thru the radiators to keep operating temps down. The cooling fans will not be triggered until the coolant temps are back up at the 200+ dergrees that you want to avoid. Not a perfect solution then and they suggest further mods to the electric fan circuit. Still digesting this. Higher coolant temps trigger the cooling fans. This lowers the coolant temps. Hmmm....may not be a big problem for "normal" driving. Any thoughts?

Fahrer

A thermostat that allows a higher flow ( more open) rate of coolant through the engine will transfer more heat from the engine to the heat exchangers ( radiators). This will likely cause the coolant to increase in temperature and the fans to kick in if the flow rate of air is not edequate to lower the temperature of the coolant. An engine that runs cooler may need hotter plugs to prevent fouling and/or may not run optimally.

cello

Well, it would appear that driving style and use, alone, are not fully determinative factors (altho the same may accelerate the process..).

I think a balanced reading suggests the condition is a 'developing' one and that the resultant 'problem' is "hot spots"; ie locations of overly high, non normal, temp in specific locations.

The 'solution' offered then is to 'average' out the internal temps to forestall the 'developing' process of cylinder 'ovalling' due to increased temps leading to increased blow by increasing piston temps leading to local hot spots where the oil will be 'cooked' and fail to lubricate/protect the liner/rings... etc.

As cbzzoom stated "The goal of the low temp thermostat is not to lower your operating temperature from 180 to 160 - it's to lower that internal hot spot from 220 to 200."

As you note, not a perfect solution mainly because the local 'hot spots' can only be 'treated' by an averaging approach without significant machining.

The only other thing I would note is that Raby/LN Engineering's opinions and solutions do not appear in any way to be 'snake oil'. Do a search on Jake Raby here and elsewhere and I think you will find his opinions/offerings on things Porsche to be well considered and reasoned and to be well informed. I am not a customer nor do I know Jake Raby personally so I have no skin in the game. But I have read enough of his posts to think highly of his opinion, for whatever that is worth. There are plenty of snake oil peddlers out there - Such a pejorative term should not be thrown about casually and should always be used with care IMO.

MichaelL

My experience with the LNE low temperature thermostat has been positive. I had a third radiator kit installed previously & did not note any decrease in normal(175 degree) coolant operating temperature. After having the thermostat kit installed, the normal operating oil temperature decreased from 220-225 degrees to 200-205 degrees. Coolant temperature was unchanged. The car always took about 5 miles of driving to fully warm up and seems to take a little longer now. This behavior, before and after, appears to be relatively independent of outside air temperature.

It is not clear to me why this is so, but 20 degree lower oil operating temperature is a benefit and worth the cost of the modification.

cbzzoom

No, I didn't mean to imply that I believe that to be true, but I know that some people do, and use it as a reason to be skeptical.

I think the technicians who are investigating these problems and possible solutions are providing us with great information, and its up to each person to make their own judgement of how to use that.

cbzzoom

As noted previously, the coolant gauge in our cars in bogus. I'm sure your coolant temp has changed. It was probably around 195 F before and is now more like 185.

To get an accurate coolant temp you need to read it from the OBDII port. People have done this (see the 996 board for example) and got those temperatures.

It's a shame that Porsche put in the bogus coolant temp gauge, but it appears to be standard industry practice now, due to too many owners freaking out when their coolant went over 212 F.