I'd like to turn on the radiator fans at about a temperature that's 10 degrees cooler than what they currently turn on at.

Is there a way to do that? Different temp switch? Reprogramming one of the computers? If reprogramming, can the Durametric Enthusiast do the job or is the Pro needed? Or some other available tool?

 

deleted - answered the wrong question

 

A shop did it for me by drilling a hole and thread into the side of right radiator, screwed a Mercedes temperature switch (85 degrees) and hooked it up to the fan electrical wirreing. Result is that the fans are coming up faster and at full speed

 

That's a great idea. Do you know the MB part number? Was there easily accessible full time sufficient capacity power in that area? Do you mind sharing your much the shop charged you? Thanks!

 

Why?

 

I now use a "low temp" thermostat and want to realize the most engine protection from it by fully utilizing the native cooling capacity of the system while traveling at low speeds in warm/hot ambient temperatures.

 

That's what the cooling system already does!

Also running the engine at a lower temperature is not great for the engine. It can cause pre-ignition detonation (knock) to a point where the knock sensor can't adjust.

Then it's knock, knock, kablewy.

 

Why???

As others pointed out, the system is already optimized. It removes as much heat as necessary from the engine, and works as desired in hot or cold climates.

The ONLY condition that a higher capacity radiator maybe needed, is while tracking regularly, and Porsche has built a 3rd radiator for that (used in X51), and that still uses the same thermostat, and holds the temp at the exact same setting, it just adds to the heat removing capacity in case that's needed.

Your application doesn't require any of this and you may even harm things by trying to hack the engine to run things 10 degrees cooler...

 

A couple of experts recommend low temperature thermostats (Flat6 and Hartech) and I am further optimizing the system under specific conditions (counteracting low speed; lesser air flow across the rads).

There's a great idea on the table to plumb in (to the radiator) an "extra" (lower temp) temp sensor to control the radiator fans. Another less sexy idea is to just use a toggle switch for when I'm in stop-and-go traffic.

And, maybe none of this will be necessary after I clean the radiators. But I'm not too hopeful about this because they look pretty clean from the outside.

 

I installed a third radiator on my 2012 997.2 last month at about 30,000 miles. The amount of garbage between the radiators and the a/c grilles was surprising. Gravel, paper, leaves etc. was easily removed with the front bumper off. It also made checking the operation of the radiator fans. They often are stuck with a piece of gravel lodged between the fan blades and the housing. The addition of a third radiator and a half gallon of Porsche antifreeze seemed to be helpful. Cleaning the standard radiators was probably just as valuable. I also replaced the coolant cap just as a precaution. I recommend the Zunsport grills especially with the third radiator. BTW, the third radiator kit for the 997.1 works very well on the 997.2. These are the parts you will need for the 997.2 third radiator:

Item Part # Quantity Amount Ship date
AIR ROUTING 997-575-141-07 1 $139.80
RADIATOR 99704410005 1 $173.22
Subtotal $313.02
Shipping (USPS - Priority (2-3 day delivery)) $10.74
Total $323.76

 

Cleaning the radiators is never a bad idea. All the other stuff, in all due respect to those experts, seems to be nothing by harmful. Here's the deal, do you overheat in traffic? If not, then WHY you need to run a lower temp engine?

The engine is optimized to operated in a certain range of tempreture, and radiator/thermostat job is to keep it within that operating range... unless you go outside of that range in your climate, then why such *mods* are necessary? The only time I ever saw my car get a bit hot, was on track during a very hot day after my 3rd session, it still didn't overheat, but I could see that maybe a 3rd radiator could have helped dissipate more heat just to ensure the engine is within the normal range again (NOT a lower temp range).

My 2 cents... you don't need it.

 

A point against a binary switch is that the radiator fans are variable speed and a simple binary switch probably wouldn't work. Even if it did I don't think you'd like the result. You normally don't hear the fans run at full speed.

When at full speed they create more of a roar than I think you'd likely be happy with. I had one running at full speed when the other fan failed (I learned from the service tech that the car detected the fan failure and turned the other one on full blast to compensate for the reduced flow). The loud fan sound was kind of embarrassing in the parking garage at work... my car sounded like a vacuum cleaner driving along.

 

Definitely don't want a vacuum cleaner sound in the parking garage. Although, if a manual toggle switch could be "cobbled in", I'd only be overriding it in stop-n-go traffic where the noise really wouldn't matter. [I'm not looking to disable the natural control of the fans just override it in a specific conditions - stop-n-go traffic so as to let the low temp thermostat bring coolant temperature to steady state.]

I didn't realize that the radiator fans were variable speed. Are they two-speed? Or infinitely variable (as in PID controller)? We might be able to figure that out by how many leads they have coming into them?

Sure wish these could be reprogrammed with a Durametric...

 

PID as in Proportional + Integral + Derivative?

 

According to the experts, creating cooling capacity "headroom" is advantageous in some conditions. Certainly related to that is to try to keep the natural hotspots (in the heads) a little less hot which provides some specific areal protection (without sophisticated instrumentation, one cannot see these hotspots by looking at just oil or coolant temp with the stock sensors).