arbeitm

I was reading a post about installing a start button to start the engine and it got me thinking.

During autocross, my engine temp seems to get very high during staging. Not into the red but it stays at the 3rd mark a lot. May be caused by a combination of high rev driving and high outside temperatures. I don't know.

But I wonder if it would make sense to install fan override switch that would let me keep the fans on high during autocross regardless of what the engine temp was. Kind of like the oil cooler fan override switches that the 911 guys do.

Anyone do anything like this? What do you think...uneccessary?

VWaddict

I'm pretty sure that if you just paper-clip the socket for the radiator thermo-switch, the cooling fan runs. If so, al you need to do is parallel a swith (with perhaps a 5-amp current rating) across the thermo-switch (i.e. wire a shorting terminal of your new switch in larallel with the two wires coming from the radiator thermo-switch socket) then it'll work as you wish.

Some thoughts:

First, remember to turn it off! Your thermo switch is permanently live. If yu leave this switch on when you park, you can drain the battery in not much time at all!

Second: disconnect the battery before you do this. -Otherwise the fan can start up and give you a nasty shock... possibly taking a finger with it. BE CAREFUL!!!

Third: a safer option is to take an ignition-switched 12V feed to the new cabin switch, then have it turn on a 12V relay primaryu coil. Take the switched contacts of the relay to the thermo-switch. That way, the relay will de-energise when you remove the key, and you can't screw youtself like in the forst situation.

Fourth: While the temerature in the engine block/head may be high, the radiator isn't necessarily all that sky-rocketingly hot... Otherwise the thermo-switch would have come on. -Of course this additional fan wiring approach shouldn't do anything particularly bad in terms of temperature, it seems to indicate that the REALLY hot water hasn't made it to that part of the radiator yet, so there's a limit to how much additional cooling you can get...

Shouldn't hurt though... Give it a try!

I had an ex-girlfriend's Opel Astra that this was done to... it did help out a bit in that case.

Keith

iloveporsches

I have this on my car now because something's wrong with the cooling fan circuit. I just bought a fused switch from radioshack, ran some wires up to the thermoswitch wires, and connected it all.

alordofchaos

That's normal, according to the owner's manual, for heavy driving.

Some people swear by Water Wetter - never tried it myself.

I've seen some fan switches (e.g., Performance Products catalog) that are supposed to activate at lower temps and I'm guessing the High position would come on sooner, too - one of the Rennlist Sponsors might have something similar.

arbeitm

Truthfully, I probably need to get my fans working properly first. Only one fan spins in the low speed mode. It's probably the resistor behind the glove box, but I haven't gotten around to it yet.

Maybe then it wouldn't jump up to the third mark so fast.

VWaddict

I think you've got things a bit mixed up... Either you have, or I have!

-The resistors nehind the dash are for the CABIN VENTILATION fans. They are series resistances to slow down the cabin ventilation fan speed.

The RADIATOR cooling fans are nothing to do with this.

Okay, that's how I understand it. I can check in the manual -but not now (I'm at work, the manual is at home) -One of us appears have it wrong, and I though I had it right...

Keith

arbeitm

These are the two resister behind the glovebox. They slow down the engine cooling fans for the slow mode. Then they are bypassed in fast mode. The relay tells the power which circuit to take based on the imput it's getting from the temperature sensor.

We may be talking about 2 seperate items?

VWaddict

Ah yes. -I appreciate the clarification. -I thought you meant the resistor pack for the AC/ventilation fan which feeds the cabin.

Keith