I sometimes think about wiring up a switch to turn my radiator fan on for added cooling. I'm wondering if there could be any downside to this. I would turn it off while I'm driving and let the car handle it then, but I'd like a switch to keep it on when I'm parked and idling for added cooling. Would it be bad to cool it down too much? Does the engine like to maintain a certian temperature?

I have also thought about a modification that would allow the radiator fan to pop on when the engine is not running (pretty unlikely it would start the fan while the car is off, but it'd be neat anyway). I'm wondering if the fan is hooked to the ECU and the software trips it, or if it's wired right to the coolant temperature sensor, or if it has it's own sensor alltogether? Actually, now that I look at it, the ECU does have a fan output that fires it's underhood relay (connector A, node 12) and coolant temp sensor input (connector D, node 13), so I guess it's software controlled, and I would need to keep the ECU powered up while the car is off. Too much hassle and battery drain, forget it! Sorry for thinking out loud. Hotwiring it with a switch between the ECU and the fan would work better.

Anyway, any downside to overcooling at idle?

Thanks,
Dougal

zelifcam

 

just leave it......your engine knows what its doing

 

Haha, yeah. But so do automatic transmissions yet we like manuals! I just like to tinker.

 

I'm not sure overcooling will be your problem. It will be like overheating.

I'm not an expert, but let's look at a few basics. The current system setup allow the cool coolant to go in to cool the engine. Once it get's hot, it cycles out, so cold coolant goes into the engine, while the fan cool the hot one that came out until it's cool. Then it cycles again. The fan (system) only operates at one speed.

If the system is flowing all the time, the coolent will never get a chance to rest and cool down. It will just constantly flow hot coolant in and out, as the fan despriately try to catch up and do it's job.

Counter Point. Many modern V8 (Crown Vic) guys do mod the electrical cooling system to operate like the old mechanical system Meaning the fan is driving by the engine (via belt of course). So faster the rpm, faster the fan. Therefore faster the flow. They felt that this provide a better constant cooling then the cycle method of the modern electrical system.

 

Unless you're road racing the car or live in areas with high heat / humidity, the stock radiator setup is just fine. Otherwise, a Spoon Thermostat & Thermoswitch will make sure the rad. kicks in 10 degrees cel. earlier, but you prolbably don't need that either.