Auxiliary fan switch relocation.

[6inarowmakesitgo!]

This can be done to any E32, E34 or E28. I take one of the plugs out of the coolant block and put the auxiliary fan switch in there and then put the plug in the radiator. Now it kicks in when it should, instead of being on the cold side of the radiator. It has prevented an overheat on the E32 and in the E28. Cheap insurance and peace of mind in case you get stuck in traffic on a hot day.  

Cheers! 

 

[YoungCR]

Good idea!

[6inarowmakesitgo!]

4 hours ago, YoungCR said:

Good idea!

Thanks! 

I forget where I stumbled upon this, but has served me very well. The B34 coolant block does not have all the bosses tapped and threaded, so you will need to either buy a B35 coolant block (recommend, as they are quite affordable and your block is probably corroded....) or drill and tap the B34 block. 

Use this in conjunction with putting the B34 rear coolant flange for the cylinder head, T it in with heater core plumbing and you now have a  better hot coolant loop for the head and heater core. 

You will have to lengthen the wires of course. 

[jc43089]

Is that on the outlet passage from the engine?  The purpose of the fan is to be sure that the coolant supplied to the engine from the cold side of the radiator is below the switch setpoint.  The main purpose to change that system is to put a lower temperature switch in when removing the mechanical fan.  For example most e36 models come with a 91/99C switch for low/high speed.  I have installed the factory 80/88C switch when removing the mechanical fan.  Then the fan will activate when the coolant supply to the engine climbs to 80C (176F) and will ramp up to high speed when coolant reaches 88C (190F).  That is plenty adequate to cool the engine.  If you supply colder coolant it just causes the thermostat to be farther closed to restrict the flow so no more cooling is achieved. 

With the temp switch there you are measuring the coolant temp coming out of the engine which will always be the same (thermostat temperature)  So there is no way to know if the coolant returning to the engine is cool enough to provide adequate cooling.  The only thing it does is run the fan excessively depending on the combination of thermostat and fan switch temperature.

Not trying to rain on your parade, just sharing what I have learned about these cooling systems.