E46 Cooling system Overhaul & Bullet-Proofing

So I bought another car (my 6th in as many years lol) – this time, it’s a 2005 BMW 325xi. It’s got 90K on the clock, and is in great condition. Oh yeah, and it’s a 1 owner car, driven by an old lady since new…that old lady?  My mother – so it’s been in the family since day 1. 🙂

Even with this car being in pristine condition, it’s an E46 BMW…meaning it’s got plenty of…uhhh…fun….issues that need to be worked through. One of those is the notoriously chintzy plastic cooling system. Below is a guide I’m drafting for E46 Fanatics on how to fix all of the crap and future-proof the car for modding.

“As we all know, the cooling systems on E46’s suck, mainly due to BMW’s love affair with cheap plastic everywhere. To add to this, my car is an xi, so it’s steptronic…which got ripped off even more in the cooling dept. In an attempt to resolve a lot of the shortcomings of the stock system, as well as setup my car for future mods (read: Full Dinan Stage 3), I’ve done a modified version of the normal cooling system overhaul.

Here’s what you’ll need if you want to do this:
New Waterpump with metal impeller – I got mine from FCP Euro
An OEM e-fan pulley is optional if you want the swap to look original – didn’t bother with this
Samco Sport silicon coolent lines
Frame Rail Mounted Oil Cooler
All-aluminum Radiator for a manual tranny car
Either an OEM electric fan or an aftermarket one – I went aftermarket because they came free with the radiator
If you go aftermarket fans, you’ll need Bosch P/N xxxxxxx to wire them in – DigiKey has them.
Manual Transmission Expantion tank bracket
New OEM expantion tank
New OEM Expantion Tank Cap
New OEM Hose Ends
4 feet of 3/4″ Silicone radiator hose – search ebay…it was like $20.
New Hose Clamps
New OEM thermastat
New OEM coolent level sensor
OEM Transmission Fluid
OEM Coolant

You’re probably scratching your head with the manual tranny stuff. But again, going back to us auto owners getting jacked harder – the cheapest all-aluminum radiator for autos is $1200…no thanks. I paid $160 shipped for my manual tranny one…with fans included.

The guist of the swap – remove your radiator, fan, clutch, tank, lines, etc. – throw it all in the trash. Also chuck the useless stock trans cooler and trans t-stat – you won’t be needing those anymore.

First mount up the radiator. Then moch up, drill, and mount the trans cooler on the front frame rail. I’ve got an M-Tech II kit, so it goes where the intercooler would normally go. Either get a black one of do a super-light coat of black paint for extra street cred. Plumb up the cooler.

Next up, assemble all of your hoses with the ends. It’s fun…not.

If you bought an OEM fan, just bolt it up and plug it in. If you went aftermarket, you’ve got some work to do.

I gave my old expantion tank and plastic ends to a metal working buddy of mine who’s going to make me aluminum replacements. That will remove all of the plastic bits from the cooling system outside of the OEM t-stat…haven’t looked at the possability of swapping the guts of that into an aluminum housing…that’d be nice if it’d work. :O If anyone wants, I can post the Solidworks files he’s making when done.”

[need to edit and fix spelling…need to add pix] – jps 10/8/13

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