gpjli2

See, the longer warm up time concerns me as does the lower average oil temperature. Longer warm up can translate into more cold start wear, and the oil is meant to operate within a range of temps at which it is most efficient. I am of two minds here. I know this may sound naieve, but if P wanted to run a different thermostat in this application why wouldn't they? They seem to have done it in different engines. I'll talk to Taso about this but he obviously was ok w it.

gpjli2

As I said above to MichaelL I too am concerned that lowering oil/operating temps may not be a win/win situation. I'm on the fence here.

aaks38

Couldnt help noticing that the LN thermostat goes for $172 and rock auto sells a replacement stant for $42

I remember back from when i used to work on muscle cars, low thermostats were a no no due to cylinder wall washing as the ecu spends more time in open loop before the engine comes up to temp..

Is there anybody else whom has had this problem aside from the guy whom just bought a used targa?

gpjli2

This is described as "rare". First I've heard of it but there is another post containing a well written article from a firm in England (Hartec)I believe who descibes this type of failure between 25-50k miles due to spikes in engine temps. I dunno what to say here. May be best to go back to worrying about IMS

Palmbeacher

Some of you should buy a primer on the basics of the internal combustion engine. Others, it isn't likely to help because they'd believe that Santa is real and the earth is flat if LN or Jake said so.

A thermostat is a simple device that can only open and close, and it does one thing and one thing only: delays the circulation of coolant through the jackets until the engine has warmed up to a certain temperature. After that the thermostat stays open, and has NO, NADA, ZERO influence on engine temperature.

The ONLY way a thermostat can lower operating temperature is if the car is not driven once it reaches the temp where the thermostat opens. Where a 160 thermostat will keep average operating temps lower than a 175 thermostat is only in the case of short-trip driving...and in that sort of service, the best thing for the lubricated parts of the engine is for the oil to be allowed to warm-up as quickly as possible.

Lubrecon

I am not a thermostat expert, but this seems to dispute your analysis of how thermostats work....."Once the optimum operating temperature is reached, the thermostat progressively increases or decreases its opening in response to temperature changes, dynamically balancing the coolant recirculation flow and coolant flow to the radiator to maintain the engine temperature in the optimum range as engine heat output, vehicle speed, and outside ambient temperature change. Under normal operating conditions the thermostat is open to about half of its stroke travel, so that it can open further or reduce its opening to react to changes in operating conditions. A correctly designed thermostat will never be fully open or fully closed while the engine is operating normally, or overheating or overcooling would occur. For instance,

* If more cooling is required, e.g., in response to an increase in engine heat output which causes the coolant temperature to rise, the thermostat will increase its opening to allow more coolant to flow through the radiator and increase engine cooling. If the thermostat were already fully open, then it would not be able to increase the flow of coolant to the radiator, hence there would be no more cooling capacity available, and the increase in heat output by the engine would result in overheating.

* If less cooling is required, e.g., in response to decrease in ambient temperature which causes the coolant temperature to fall, the thermostat will decrease its opening to restrict the coolant flow through the radiator and reduce engine cooling. If the thermostat were already fully closed, then it would not be able to reduce cooling in response to the fall in coolant temperature, and the engine temperature would fall below the optimum operating range.

utkinpol

https://www.lnengineering.com/lowtem...hermostat.html

you cannot just unplug the hose and put it in, as you noted - air has to be vacuumed out of the system, so, consult with a good mechanic if you do not know how to do it yourself.

it is a very typical track upgrade and if you suggest it - it will not hurt to put a 3rd radiator in as well.

utkinpol

no. issue is with how fast internal block temperature rises while thermostat gets open and heat keeps accumulating in the block when colder coolant just starts to arrive. with track normal RPMs close to redline this internal warmup happens quite fast.

i do not think any of those changes are needed for those who only drive their cars on the street - it will never be abused that much and with RPMs at 2K-4K range there is no danger of overheating anything. sustained RPMs in 5K-7.5K area are different deal, especially if combined with ECU flashes that increase block heat even more.

gpjli2

Did you read the Hartech article? He states the exact opposite. Large throttle openings at low rpm cause temperature spikes in the head too fast for the thermostat/coolant to react to and correct. At sustained high rpm's the cooling system is in full open mode. According th Hartech it is the temperature spikes, hot spots and uneven cylinder cooling that causes this type of failure not high average temp or the # of radiators. What you are addressing is a problem but is not the focus of a thermostat change.

1BlinkGone

One thing I'd like to chime-in about here is the Thermostats themselves. IMHO, always go with OEM... ALWAYS.

I don't know about Porsche, but in every other foreign and domestic application, I've found much shorter lifespan (like about 12-16 mos, irregardless of mileage) with aftermarket units (like Stant) vs OEM from the dealer. Without fail I have found this to be true.

And when they fail, 95% of the time they stick shut, not open, which can cause worse problems ( blown radiator tank seals, head gaskets, etc).

For the few bucks extra (in many cases just $2-$3) to buy OEM at the dealership's parts counter, I'll go OEM everytime for a thermostat.

Palmbeacher

All true except the very last sentence, and none of it disputes what I said, in fact it supports it. A thermostat can only regulate the flow of coolant. It "controls" temperature ONLY within the capacity limits of the cooling system. Once the capacity is exceeded (see where I bolded above) an automotive thermostat will most definitely be open fully (it had better!) Think of the A/C in your car or home. It's 95 degrees out, you have the thermostat set to 75 and the compressor is running non-stop with the fan at full speed, but the inside temp doesn't seem to want to go below 80. Turning the thermostat down to 65 will accomplish nothing, because the A/C is already running at full capacity.

Palmbeacher

IF that is the issue, then what is needed is a more sensitive cooling system, capable of reacting quickly and exchanging heat quickly. Better-designed radiator(s) and specially-formulated coolant would be the primary goal. A more sensitive/reactive thermostat would be an ancillary part of such a theoretically enhanced cooling system. A lower-temp-rated thermostat will not address that issue, just as it will not address the issue of an engine running consistently too hot. The fact someone supposedly in the know proposes it will, is a staggering admission of ignorance.

However it is not the above-quoted issue for which the 160-degree thermostat is rationalized by the seller. The reason cited for the thermostat change is that the bearing lubricant is foreshortened drastically at operating temperatures above 250F. In that case, a supplementary oil cooler would be the most effective way to address the issue, not a lower-rated coolant-system thermostat.

Another misunderstood, misinterpreted concept is the reason why "tracked" cars seem to suffer fewer IMS failures. As an engineer I can say with certainty that it has insignificantly little do to with EHD film, as the "retired bearing engineer" supposedly asserted. The difference between the rotational speeds of the IMS bearing at engine RPMs between 1000 and 5000 would not correlate to a significant-enough difference in formation of EHD film to matter. The reason higher RPMs help is because once the seals are breached the faster the bearing rotates, the more effectively it impels and expels oil. And the more frequency with which the oil in the bearing is exchanged, the less likelihood there is for burnt, acidic and/or abrasive-contaminated oil to attack the bearing. Another advantage given tracked cars is frequent oil and filter changes...further evidence.

Lubrecon

Where is all of the discussion on tracked cars and IMS failures? Who is the retired bearing engineer? Where is the data to support EHD lubrication versus boundary or full fluid film lubrication in the IMS area?

Looks like pointing out discrepancies in one's post is in the eye of the poster. It would seem that Hartec's investigative efforts and study of the over heating problem cannot be dismissed as easily just a thermostat and it's functional capabilities, but then he goes into depth about how the thermostat can help in this area. For now, I'll give Hartec the benefit of the doubt, since his livelyhood depends on his expertise and experience with scored cylinders and the root cause of same.

gpjli2

Read this months article in Total 911 for a treatise on ims failure. Their position is that the bearing fails because it is sealed and over time, when the grease is lost, cannot receive oil spray lubrication. The harder the engine is run the greater the chance the ims bearing will benefit from lubrication spray. It also appears that in some/most engines the seal degrades enough over time to allow oil in. Apparently if you replace the bearing with an unsealed oem bearing you can help your cause. My advice to you sir, completely unsolicited is to do the following: When you are ready buy the most recent and best maintained Porsche 911 you can afford and drive the hell out of it. As you yourself suggested, there will always be something. You will come to rue the time lost waiting. It is truly a wonderful car. Gerry

Palmbeacher

Sorry, I thought everyone knew. It's on the website of the company who manufactures the aftermarket IMS bearings and the 160-degree thermostat, and in tons of posts by another individual who covers all the Porsche forums with tales of ongoing daily arrivals at his garage of multiple "grenaded" M96-engined Porsches. Not the data you asked about however...they offer no verifiable data whatsoever.


That sounds like a plausible explanation, but 1)the engine was not designed so that the IMS bearing would receive adequate engine-oil lubrication, and 2)the OEM bearing is designed with looser internal tolerances in anticipation of being packed with high-viscosity grease. Therefore, it would seem that the sensible thing would be to either replace the OEM bearing with a new, grease-packed and sealed one; or use the LN bearing which is made to be oil-lubricated, and made of materials more apt to withstand the inadequate oil supply.

What would probably be the simplest and most effective cure for this issue would be redesigned IMS bearing seals of a material capable of withstanding the heat and oil, and which therefore would allow the grease to remain intact. Surely such a synthetic exists.