Cooling Refresh

[Andrew 06M3Cab]

I am about to do a cooling system overhaul on my 06, with 220,000 km. It's pretty much all original, although the water pump was replaced around 100,000 km ago. Recently on really hot days the water temperature has started to climb, to the point where I have had to turn off the AC to keep it within range. The oil temps remain fine, pretty much always pegged at 12 o'clock on the gauge. I think the radiator is probably shot, and while the fan clutch seems to be in good shape, I worry about the fan being brittle and shedding a blade or two.

I am thinking of replacing the mechanical fan with electric (Spal with 2024 cfm), and the stock rad with a CSF rad. I have a couple of questions though.

Is it worth replacing the oil cooler preventatively? My only hesitation really is the cost, which isn't cheap when factoring in the cooling lines (it is approaching the cost of the whole water cooling system). As mentioned, my oil temps are always good. I was looking at the CSF oil cooler also, which almost the same price as stock at the moment. I have never had any issues with stock, don't track the car, but do the occasional HDPE.

When swapping to an electric fan I don't plan on removing the aux fan. What are people using for an additional PWM controller? I haven't seen many reviews on these. One I was looking at was the 50 amp from "Auto Cool Guy", but I am a bit hesitant given the lack of reviews I have seen.

Lastly, everything electrical on the car is currently stock, but there would be additional drain on the electrical system with the new electric fan. I have not decided yet, but thought if I was going to change everything, now would be the time to install an underdrive pulley kit if I was going to go in that direction. With a new and upgraded rad, I don't see an issue with reduced cooling from underdriving the water pump. But what about the increased demand from the alternator associated with the new electric fan? Think there would be issues?

Thanks for your input.

[Obioban]

Stick with the stock radiator and oil cooler. They just work better.

[erickhoyos]

You can run a lot of electrical accessories without any problem. The M3 is not like a Foxbody with a weak 1G alternator. Stock oil cooler works just as fine, if not better than aftermarket. Aftermarket oil coolers have bigger capacities therefore you need to add more oil to the car. I have a CSF radiator with Mishimoto electric fan and it does the job but can’t compete with stock.

[Syfon]

Personally I wouldn't replace the oil cooler unless you're tracking the car and you need the extra cooling capacity.

If oil temps are fine, don't waste your $$.

I replaced my cooler and lines; only due to a spun bearing and copper pieces being stuck in the cooler. It's impossible to flush an oil cooler and remove all foreign material.

[Andrew 06M3Cab]

Thanks. I was wondering whether it was even necessary to do the oil cooler. I will probably wait until it shows some abnormality.

[jareds941]

I track my car with the stock cooling system and have no issues. I don't think an electric fan is even necessary unless you're actually having an issue. And if you're in TO, I can't imagine you really will see crazy temps (I'm in OR, and usually it's mellow here...but it's also supposed to be 108* here this weekend, so 🤷♂️)