M30 Guys: Coolant expansion tank details needed

[CorvallisBMW]

ever get this figured out?

Actually, yes! Raising the expansion tank up ~1.5", so that the cold fill level is even with the bleed screw, completely solved my issue! The more I think about the basic physics involved, the more it makes sense. Fluid levels will always equalize in a closed system as long as the pressure inside has the ability to equalize. So having a coolant fill level below the bleed screw = air in thermo housing. I haven't seen any air'bleeding issues since I did this. My OEM fan switch system is still not reliable however. Sometimes the fans come on when they are supposed to, and sometimes the temp gauge gets over 3/4 before they wake their lazy asses up. So I'm going to be installing the PWM fan controller and a smaller diameter water pump pulley. This was apparently fitted to hot climate cars to speed up the water pump: http://bmwfans.info/parts-catalog/E3..._fan_coupling/

[LowR3V'in]

haven't really tested this seeing it's fall/winter time BUT you can feel all the air getting sucked in through the kidney only.
before it was pretty weak meaning it was sucking in air from all around including the engine bay.

hope this helps any future people.
Duct you by jet jones, on Flickr
Duct man by jet jones, on Flickr

[LowR3V'in]

ever get this figured out?

[CorvallisBMW]

I used to have alot of cooling issues with my swap: overheating in traffic, fan not kicking on at the appropriate temperature, etc.

I replaced the thermostat (including drilling a hole), the water pump, the radiator temp switch (80/88 C), and the sensor that plugs into the thermostat housing.

Now, the temperature gauge is pinned at just over 1/4 whenever I'm at speed. If I'm idling in traffic for a while, the 16" SPAL fan will kick on like clockwork at just under 1/2 and the temp gauge never strays over halfway.

Not sure what did it: the new parts, opening everything up and getting a real good proper bleed, or just dumb luck. All I know is that solved my issues, so if you continue to struggle maybe think about replacing a few of those things

Sometimes it's dumb luck, sometimes it's bad parts, sometimes it's a complete fuckin' mystery! I've replaced all those parts and it never solved the issue, though I'm happy to say that after a couple cruises with the raised expansion tank I have yet to see any more air from the bleed screw and the fans seem to (finally) be reliable! I ordered a PWM setup though which I'll install after teh Picnic, as I really don't like the massive amperage spikes that come from the stock relay setup.

This may or may not help but i feel that it probably will.

just messing around in the garage
instead of the fan drawing from all around it basically the engine bay / radiator air.
do something like this to get it to draw mostly from out the grill.

just doing this side i can feel much more sucking power on that side.

in my car when it's basically under 80f the car will do fine
but will over heat in traffic once everything is blazing hot
including the intercooler, but if it draws from the outside idk.
Especially with that little 8amp fan.
no intercooler you can get a big ass monster shouldn't overheat.

Ah, like an inlet gasket versus an exhaust gasket. I've got the Spal fan gasket on the exhaust (between the fan and radiator) but I suppose a custom fab'd one on the inlet side would be beneficial as well.

^^ Great points.

I forgot to mention that I also added a fan shroud in between my front core support and the radiator. Prior to doing that, you could feel the air from the pusher fan shooting straight up into the atmosphere when you opened the hood. Clearly it was not operating very efficiently.

Now, the cooling air is contained and pushed straight onto the radiator. I have to imagine this is helping quite a bit compared to the previous setup.

I used this radiator support bracket and modified it with a dremel to fit the M535i radiator. It fills the gap perfectly on mine (see photo)

https://imgur.com/7Mv6wAZ

Yes a gasket around the fan exhaust is really helpful. Definitely worth the $15 or whatever Spal charges for them.

[dishwab]

^^ Great points.

I forgot to mention that I also added a fan shroud in between my front core support and the radiator. Prior to doing that, you could feel the air from the pusher fan shooting straight up into the atmosphere when you opened the hood. Clearly it was not operating very efficiently.

Now, the cooling air is contained and pushed straight onto the radiator. I have to imagine this is helping quite a bit compared to the previous setup.

I used this radiator support bracket and modified it with a dremel to fit the M535i radiator. It fills the gap perfectly on mine (see photo)

https://imgur.com/7Mv6wAZ

[LowR3V'in]

This may or may not help but i feel that it probably will.

just messing around in the garage
instead of the fan drawing from all around it basically the engine bay / radiator air.
do something like this to get it to draw mostly from out the grill.

just doing this side i can feel much more sucking power on that side.

in my car when it's basically under 80f the car will do fine
but will over heat in traffic once everything is blazing hot
including the intercooler, but if it draws from the outside idk.
Especially with that little 8amp fan.
no intercooler you can get a big ass monster shouldn't overheat.

Fan funnel by jet jones, on Flickr
Maybe out of abs by jet jones, on Flickr

[dishwab]

I used to have alot of cooling issues with my swap: overheating in traffic, fan not kicking on at the appropriate temperature, etc.

I replaced the thermostat (including drilling a hole), the water pump, the radiator temp switch (80/88 C), and the sensor that plugs into the thermostat housing.

Now, the temperature gauge is pinned at just over 1/4 whenever I'm at speed. If I'm idling in traffic for a while, the 16" SPAL fan will kick on like clockwork at just under 1/2 and the temp gauge never strays over halfway.

Not sure what did it: the new parts, opening everything up and getting a real good proper bleed, or just dumb luck. All I know is that solved my issues, so if you continue to struggle maybe think about replacing a few of those things

[CorvallisBMW]

IIRC I have an e28 535i radiator, not sure what brand though.

I like the idea of a radiator with aluminum end tanks, that E60 one looks interesting.

[lukeADE335i]

Which radiator are you running Corvalis? Looks thicker than my e28 one, but might just be the angle of the photo (or brand, I have a Behr).

I've been toying with the idea of running an e60 radiator - it's bigger with thinner aluminium end tanks. The end tanks would allow the core to move further forward for more room in front of the engine.

Would need mods to the end tanks to clear the chassis rails though (or a notched frame, which seems a bit overkill for radiator clearance)!

https://www.fcpeuro.com/products/bmw...hr-17117519209

[CorvallisBMW]

My 16" pusher is centered right on the AC condenser. Puller is in the only place it will fit

IMG_0193 by Darin Schnoor, on Flickr

IMG_0192 by Darin Schnoor, on Flickr

[LowR3V'in]

ya maybe.
just shift the pusher to passenger side and put the puller all the way to the driver.

[CorvallisBMW]

I need to get a fan gasket and see how that improves that cooling. Right now it is flush to the radiator and hard mounted to the core support with brackets and a foam between the fan and radiator. I wanted to get a smaller puller fan(10") then mount it inside the bay offset to the bottom passenger side.

i have the thinnest pusher 16'' spal makes.
once it gets to like 20mph it'll drop. not a cooling issue just
the fan is a baby. usually when it gets into the 90s.

You can fit a 10" puller in front of the alternator, or probably something larger down by the AC compressor if you've removed AC.

[LowR3V'in]

i have the thinnest pusher 16'' spal makes.
once it gets to like 20mph it'll drop. not a cooling issue just
the fan is a baby. usually when it gets into the 90s.

[F34R]

How do you have your 16" pusher mounted? Is it directly on the radiator or spaced out a bit? I found that mine was spaced out around 1/2" and a lot of the air was just hitting the radiator and bouncing off instead of going through. Spal makes fan gaskets though, installing one of those made a HUGE difference.

I need to get a fan gasket and see how that improves that cooling. Right now it is flush to the radiator and hard mounted to the core support with brackets and a foam between the fan and radiator. I wanted to get a smaller puller fan(10") then mount it inside the bay offset to the bottom passenger side.

[CorvallisBMW]

Seems odd that your car overheats. How high are the ambient temps were you are? Is it humid? Are you running AC?