E30 M3 fan switch upgrade.

[wezzer-45's]

Hi, ladies and gents.

I'm in the process of getting my e30 ready for use this summer after being in hybernation for the winter.
One of my jobs is to replace a load of coolant hoses and to replace the fan control switch to switch at a lower temp.
I use the car back and fore work and will spend most of my journey in traffic, I would feel happier if I knew the fan would come in at a lower tem pas I am paranoid of over heating.

My switch now is 91 / 99 degrees and I have found a mod for a 325i to fit an E36 80 / 88 degree switch.
Here is a link for the 325i mod.

http://bmwsport.net/bmw-tech-mainmenu-100/bmw-e30-...

My question is, does anyone know if the E36 switch has the same thread as my M3 and therefore fit.

Thanks in advance.

[BenGismo]

I dont know much about this at all, but I thought I'd have a look on real oem to see what it says.

E30 M3 Radiator: (your thermal switch is part no 61311378073) No 17 on the diagram
http://www.realoem.com/bmw/showparts.do?model=1005...

The part you were considering putting on (80/88C SWITCH) is pn: 61318361787 (part 10 on this diagram)
http://www.realoem.com/bmw/showparts.do?model=CT31...

The screw plug used to house both these thermal switches on to the radiators is exactly the same! M14x1.5 so one switch can be physically mounted in place of the other without a problem. (at least it looks that way anyway)


Only problems I would see is:
- the 80/88C switch you are wanting to use has technically been ended by the parts department and replaced by a 91/99C one, so you might struggle to get a hold of the 80/88C one.
- Its not clear if both switches have the same electrical connection (same 3 wire plug)?? Id assume they do but without physically seeing it, its not obvious.

Lastly, its probably overkill to put in a lower temp switch. The engine and oil will be designed to work at 100C+ without problems. You will effectively be running the engine cooler by 10C all the time so oil will slightly more viscous etc...


As I say im not an expert though so take everything above with a pinch of salt. Hopefully someone can add a slightly more knowledgeable answer.

[E30M3SE]

BenGismo said:

its probably overkill to put in a lower temp switch.

This.

If your cooling system is up to scratch, the fan is working at both both speeds, the stat, pump, expansions bottle & cap, hoses (don't forget the little hose that lives under the alternator), the heater valve and matrix are all good then it should not even be an issue.

[pikeyboy]

If you want to do anything replace the wiring that controls the fan from the switch, from memory it runs along the bottom of the rad. They go brittle with age as do the connections and cause intermitent fan switching. Mine did hours and hours on track with a standard rad and cooling system, no problems, ever.

[wezzer-45's]

Thanks for the replies guys.

I tested the radiator temp this evening with a infra red thermometer.
The rad surrounding the temp switch went upto 102 degrees without ant fan operation.

I know the fan is good and the high and low speeds relays are good because if shorted at the fan switch connector, the fan will run at both speeds.

It looks like I have a dodgy switch anyway so I thing I will replace it for the correct M3 item.