Thermal Switch for Elc Fan. What are you running

[MonkeyMadness]

Ok so I have been prof'ing out my build and at this point I only have one issue/ problem i need to solve.

I am currently running a E28 535i radiator. This rad came with two thermal switches on the rad stock.



I was doing some heat cycling of the cooling system.
when manually switching on the fans it keeps the motor nice and stable.
My issue is that the thermal switches are not turning on the fans. The system works and works well but I can't seem to get the thermal switches in the rad to react to the heat and switch on. I'm running in-line relays so the switches are not pulling a load.
I have my small puller fan on the low temp switch and my big pusher fan on the high temp switch.

I'm just looking to see what you guys are doing. I was thinking of using block/ motor mounted thermal switches but I'm not sure where I wound tap in two run to switches?

I'm also interested in knowing what temp you have your fans switching on?



thanks for you input

[bmk]

While i am not using the e28 rad i am using a e36 rad. Im pretty sure they use the same switch. I replaced the factory 3 pole 90/94c (low/high speed) with a 80/88 and seems to work great, it almost runs too cool at times. I am using a volvo 2 speed fan, on high speed is pushing close to 3300 cfm. I wired it driectly to the hot power through the volvo 2 speed relay. Easy as can been. Let me know if you want any more details.

[MonkeyMadness]

well i switched to two new thermal switches.
low temp went from 91* to 88*

and the stayed with 99* with the high speed but went with a new one.
also have my large pusher setup on the low temp switch and my smaller puller on the higher temp switch.

Large pusher!

http://www.r3vlimited.com/board/showpost.php?p=4190299&postcount=385

Small puller!

http://www.r3vlimited.com/board/showpost.php?p=4190304&postcount=386

Vid for interest!

[Old city bimmer]

I'm running a 3 row rad but I'm using a stock z3 temp switch. runs super cool.

[eurotrash]

The Thermo swithches are grounds. Are you trying to run them as hot leads? I used a taurus fan with a volvo controler and an e36 2 speed thermo switch. Should run from switch to ground side of relay.

[Poorboyz]

I've been using a FAL fan controller but have also heard good things about the Spal fan controllers.

[MonkeyMadness]

yea looks like i will have to find a good fan controller. swapped out my thermal switches and they still don't come on even at 3/4 temp hot.. ugh
I'm only using that as a ground from my relay...

oh well I will be looking in to finding something trick...

[JGood]

The stock fan switch/relay system is more then adequate, I'd figure out what's wrong with it before installing some aftermarket junk.

Is your switch engaging at the specified temp? You should have continuity across the pins. You can test it in a pot of water. If not, that's a problem, you have a bad switch. If it does work, then your wiring is wrong.

What do you mean you're "using that as a ground from your relay"? The stock e30 aux fan switch is power to the relay, not ground.

Fuse 19 should feed power to both of your fan switch inputs. You low temp switch output should be wired to the normal speed relay pin 86. The K1 (normal speed) relay pin 85 should go to ground. Normal speed relay pin 30 should be constant power, and pin 87 should go to fuse 3 (15 amp), then to the fan (through the fan resistor on a stock setup). Similar setup for the high speed relay.

[lukeADE335i]

With my M30 swap (same e28 radiator) I had to move the thermo-switches to the thermostat housing to get them to switch correctly. In the thermostat housing they're getting hot coolant from the outlet of the head. The S14 engine is set up like this.

The stock switch location on the e28 radiator is on the cold side of the radiator, not the hot side, so the switches are reading cooler than the temps at the head and hence switch the fans on when the engine is hotter than the switching point of the switch.

Not sure why BMW did this as the early stuff (eg. e21 etc.) has the thermo-switches mounted on the hot side of the radiator, not the cool side.

Is there a spare bung to mount a switch in the thermostat housing on the M60?