Cooling your m30

[TimeMachinE30]

On mine I just used the stock wiring for the e30 Aux fan. It's on a 30 amp fuse, so works fine. The trick is to use a lower temp fan switch - the two popular options seem to be an e36 80/88 degree switch, or an 82 degree switch from an e28.

I just run my fan as a single speed, with the 82 degree switch from an e28. I run the switch in the thermostat housing so that it gets a correct read on the engine temperature - the switch mounted in the side of the radiator can be a bit hit and miss.

I've run this setup for over 100,000km and have had zero overheating issues, even driving in traffic in over 100F, which we get fairly regularly down here in summer... it's going to be 106F today!

Got it. Thanks. I appreciate your build knowing you DD the swap in your down under heat.

[lukeADE335i]

No problem - happy to help. Good luck with getting your cooling system running reliably!

[CorvallisBMW]

I just run my fan as a single speed, with the 82 degree switch from an e28. I run the switch in the thermostat housing so that it gets a correct read on the engine temperature - the switch mounted in the side of the radiator can be a bit hit and miss.

I'm still using the switch mounted in the radiator and I agree, it's temperamental as fuck. It never comes on like it should. Maybe I'll switch the 80/88C for a 90/98C and place it in the thermostat housing.

[lukeADE335i]

Seeing as you're having issues Corvallis - I'd try shifting the 80/88 to the thermostat housing. It may work fine, but if the fan then doesn't switch off ever with the engine up to temp, you could swap out the thermostat for a 71 degree one.

The 71 degree thermostat was a factory option for hot climates so there shouldn't be problems with rich running etc. at the cooler temperature. I've run the 82 degree switch with the 71 degree thermostat for years and it has worked well.

https://www.turnermotorsport.com/p-1...34-e36-e39-z3/

[CorvallisBMW]

Seeing as you're having issues Corvallis - I'd try shifting the 80/88 to the thermostat housing. It may work fine, but if the fan then doesn't switch off ever with the engine up to temp, you could swap out the thermostat for a 71 degree one.

The 71 degree thermostat was a factory option for hot climates so there shouldn't be problems with rich running etc. at the cooler temperature. I've run the 82 degree switch with the 71 degree thermostat for years and it has worked well.

https://www.turnermotorsport.com/p-1...34-e36-e39-z3/

Interesting, 71C seems really cool but I guess these engines were designed back in a time when efficiency wasn't paramount so cooler temps were more common.

I'm strongly considering moving away from the factory switches/relays and going to a full PWM setup. Brushed DC motors don't really like being kicked on to 100%, it tends to wear them out. That's not a problem if you're using your fans only for auxiliary cooling when needed because you have a mechanical fan that does 95% of the work. But in my case the electric fans are the only fans so they're starting/stopping dozens of times each trip I take. There's also a huge inrush current when the 88C circuit closes and my 16" ramps from low to high and the 10" kicks on to high as well. I can hear, feel, and watch the RPMs drop as the load on the alternator spikes. A PWM controller setup would mean longer fan life, less alternator wear, and lower noise. I've been doing a lot of research over the past few days and I'm really liking this guy's products: https://www.autocoolguy.com/product-page/auto-cool-55

[lukeADE335i]

You're right - the on or off setup is tough on the fans. I'm still running a curved blade e32 fan for my setup, but it's the second one. The first one I got around 3 years of daily driving out of before it died, then the second one has lasted 4 years so far but is starting to get a bit noisy now. Neither fan was new though, they're just wrecker fans with unknown history.

I have an e39 fan in the shed I'm going to run when the current one wears out.

That controller looks good - I like the way they go right up to 200 amps!