Hello Folks,

I see a lot of reference to the -10* fan mod, but haven't found any info on how to do this and would be really grateful if someone would be kind enough to explain what needs to be done. I assume the mod means the fan kicks in earlier - would would be pretty handy!

 

here ya go bro! i wont say search because this is found on a different forum and most dont know this mod exists. m/b dealers dont like to do this as it isnt in line with "factory " standards. any indie shop with star das can do it and it costs about 50$.
i had mine done by buckhead imports and it definatly helps in the summer
C32 Star DAS How-to - MBWorld.org Forums

 

Two questions, Krazy:

That the Buckhead Imports in Atlanta just off West Paces Ferry Road?
Did they know about the mod or did you need to explain it?

 

jason cummings owns the shop and im from nashville so i dont know if its off that road or not. the addy is 28 irby avenue atl ga
yes they know all about it they are a mercedes and bmw shop.

 

Yea, tha'ts the one! Never been there, but I'm gonna go up and see them!

Thanks.

 

jason is a great guy so is kevin and tony. you wont be dissapointed

 

why not change the resistance to the sensor so that it reads 10 degrees hotter, wont this have the same effect...

 

i dont know the answer to this question. i had it done when my tune was done and it can be changed back without any issues. the mod can also be done to more than -10 if you are in say AZ. i started with my fan kicking in at 155*F but threw codes in the tn winters so i had it raised to 180*

 

Even is you COULD do that, the ECM/PCM would have bad information... sure, the fan would run, but the computer would be thinking the engine is warmer than it really is.

 

I suspect Rudy (rcompart) and others here could provide an answer as to what this "lie" would possibly cause the ECM to do. The ability to modify the fan turn-on temperature is there for a reason. If you want your fan to come on earlier, it's the way to do it.

(Or at least a BETTER way to do it).

You know, if I can go farther than -10f, I think I want it on at the same temp the thermostat is set for. No need to let it get any hotter than the thermostat is trying to limit it to.

 

Remember, we are assuming our car is overheating. So think outside the box a bit and I'll try to walk us through this. Lowering the temp at which the fan starts, or thermostat opens doesn't change the cars operating temperatures unless you set them above normal operating temperatures. Even then, your engine will try to finds it's groove. Setting the fan to come on, or the thermostat to come on at 150 still means a car that operates at 190 will still go right to 190. Better transfer of heat is the only way to make a cooler running engine. Fluids that transfer heat better, or finding ways to increase the flow of fluids can change things. Even then. if water is passing through the engine faster than the the radiator can cool it, then you might still have a problem.

Then there's air. More air flow. IE, a bigger fan, and or radiator. or creating areas to pass more air through the radiator. And plenty of room to allow to escape can cool an engine down.

The third thing is that a system that isn't boiling over is not overheating. It may not be cooling well, But until it fails, it's working. Which brings me to the last trick. Raising our boiling temperatures. This can be done with Coolants or raising the systems pressure. The higher the pressure, the lower the boiling point. But you can't have your cake and eat it here either. To much pressure causes other failures. We aren't building steam engines. Higher coolant ratio's are bad too. Water transfers heat much better than coolant In the end, it's a symphony. It's a system where any weak link in the chain can wreak havoc till you find the culprit. Ask any Street Rodder...

Remember, the thermostat is only there to allow the engine to get up to temperature faster. Our electrics fans do the same exept they actually cool, and moderate the engines temperature. If your car overheats when the fan is running, what temperature it started running at is immaterial. Your just masking a failure.

 

lets try not to overthink this mod. by turning the fan on sooner you are pulling frontal air thru the rad and aiding in the cooling process. turn it on too soon and the engine wont heat up enough in colder weather. non issue if you live in a hot yr round climate.
my cooling mods are extensive and this is only 1 in a continuing line to cool the engine.

 

Waldig put a 330 Ohm resistor acros the thermistat wires to do this. The post is called "cooling 101" or something like that.