Home
Cooling

BMW Cooling System Parts & Accessories for BMW 3 Series E46 (1999-2005)

The cooling system is arguably the weakest point in numerous BMWs. If you drive an aging BMW or plan on taking your car to the track like we do, we recommend beefing up your cooling system before going to the track. Generally, the main components in your cooling system that are prone to failure include the following: expansion tank, factory hoses, water pump, thermostat, fan (especially if your vehicle comes factory with a clutch fan), and radiator. Factory BMW expansion tanks are plastic and prone to either breaking off at connection points or combusting. As factory rubber hoses age they either crack or break over time - we offer silicone cooling hose upgrades for most applications to avoid future failures. If you have an older vehicle, your water pump likely comes from the factory with a plastic impeller - we offer upgraded water pumps with metal impellers that are far more reliable. Newer model BMWs utilize electric water pumps - BMW spent millions of dollars engineering these water pumps, but they fail so often that we recommend replacing at 60,000 mile service intervals to avoid being stranded on the side of the road. In terms of thermostats, we offer various upgraded thermostats for racing applications. If your BMW utilizes a clutch fan from the factory, we have several options available in terms of universal electric fans - we recommend replacing these to avoid sending brittle plastic fan blades through your hood. For radiators, we recommend swapping out your radiator for one that does not use plastic connection points like your factory radiator.

Sub-Categories

Sort By:

OEM Nissens Radiator - Automatic - E46, Z4

For vehicles with automatic transmission only

T#:362222

Part#: 17119071519

In Stock

$ 173.39

This product was last offered at the strikethrough price on
06-02-2026

$ 165.05 USD

Add to Wish List

Qty

$ 165.05 USD

Add to Wish List

The cooling system is a weak point on any E46. Many cars develop issues in as few as 50,000 miles.

Overheating an inline 6 engine almost always results in large repair bill, and sometimes a warped cylinder head.

Replace yours with a high-quality OEM Nissens radiator to prevent further issues and potential overheating.

Show More Show Less

Moroso Performance Aluminum Expansion Tank - E46 M3

T#:568945

Part#: 63793

In Stock at Vendor

$ 433.99 USD

Add to Wish List

Qty

$ 433.99 USD

Add to Wish List

If you have ever experienced a leaking plastic BMW expansion tank you will realize the value of this aluminum version straight away. Even if a failure has not happened to you, it's easy to tell this tank is much stronger and more durable than the plastic used in the stock design. The original BMW plastic tanks suffer from leaks and failures with no warning. While being lightweight and recyclable, the design and construction of the stock tank is just not up for reliable long-term use. Moroso coolant expansion tanks are all pressure tested for guaranteed leak-free operation. Features: Direct bolt-in replacement to stock, cracked, or discolored tanks Fabricated Aluminum for strength, factory tanks fail after repeated high heat situations & age No cutting of factory hoses is required and accepts the factory clip-on hose Included is a Moroso Part No. 63324 racing radiator cap that operates in the same pressure range as the factory cap The Moroso radiator cap mounts to a billet aluminum neck that will not strip out like plastic threaded necks Easy to read slight level is included

Show More Show Less