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Rein BMW Cooling System Parts & Accessories for BMW E46 M3 S54 (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.

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OEM Rein Upper Radiator Hose - E46 M3

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T#:2306

Part#: 11537830716

In Stock

Sale - Save 36% $ 33.99

This product was last offered at the strikethrough price on
05-06-2026

$ 21.84 USD

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Sale - Save 36%

$ 33.99

This product was last offered at the strikethrough price on
05-06-2026

$ 21.84 USD

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Replace your cracked or leaking radiator hose to prevent further leaks and potentially catastrophic failure. This hose replaces the Upper radiator hose that connects the thermostat housing to the radiator.

This Upper Radiator Hose fits the following BMWs:
2001-2006 E46 3 Series M3, M3 Convertible

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OEM Rein Lower Radiator Hose - E46 M3

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T#:2674

Part#: 11537830715

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Sale - Save 5% $ 23.99

This product was last offered at the strikethrough price on
06-29-2026

$ 22.79 USD

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Sale - Save 5%

$ 23.99

This product was last offered at the strikethrough price on
06-29-2026

$ 22.79 USD

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Replace your cracked or leaking radiator hose to prevent further leaks and potentially catastrophic failure. This hose replaces the lower radiator hose that connects the radiator to the thermostat housing.

This Lower Radiator Hose fits the following BMWs:
2001-2006 E46 3 Series M3, M3 Convertible

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E46 M3 Radiator Hose - Upper And Lower

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T#:20617632

Part#: 11537830715KT

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Sale - Save 5% $ 53.98

This product was last offered at the strikethrough price on
06-29-2026

$ 51.28 USD

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This product was last offered at the strikethrough price on
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$ 51.28 USD

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Both thermostat housing hoses to replace your worn out rubber and brittle plastic connections.

Over the years and with exposure to extremely hot coolant, the coolant hoses in your vehicle can take a beating. Being made of reinforced rubber, these hoses can fail in a number of ways. Splitting at a hose clamp, swelling, cracking, and breaking are just a few of the ways this hose can leave you stranded. Replace it at the first sign of wear to keep your coolant in your engine.

Comes with both upper and lower thermostat hoses: 11537830715 Lower + 11537830716 Upper

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OEM Rein Expansion Tank Cap - BMW E32 E34 E36 E38 E39 E46 & More ...

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T#:340541

Part#: 17111742231

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This product was last offered at the strikethrough price on
06-29-2026

$ 17.09 USD

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This radiator expansion tank cap is used most BMW's from 1991-2006. It is a common failure item. When this item fails, it cannot hold pressure which results in your BMW overheating. If you are overhauling your coolant system, now is the time to consider preventative replacing this cap. It is also referred to as the coolant reservoir cap.

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Rein Coolant Bleeder Screw CHW1575 - Priced Each

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T#:591955

Part#: 17111712788

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06-29-2026

$ 3.87 USD

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Coolant Bleeder Screw is a critical component for maintaining your BMW’s cooling system. Designed to release trapped air from the coolant lines, this screw ensures efficient coolant flow and prevents overheating. Specifically engineered for BMW models, it enhances the overall performance and longevity of your engine by maintaining proper temperature regulation. Comes with O-Ring.

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BMW Radiator Hose Kit - 11537830715

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T#:46719180

Part#: CHK0376R

Back Ordered

Sale - Save 6% $ 43.99

This product was last offered at the strikethrough price on
06-29-2026

$ 41.48 USD

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$ 43.99

This product was last offered at the strikethrough price on
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$ 41.48 USD

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Keep your cooling system sealed, strong, and ready for anything with this Rein radiator hose kit—your all-in-one fix for cracked, leaking, or worn factory hoses. Years of heat, pressure, and age can cause rubber to weaken, split, or swell, setting the stage for coolant leaks and potential overheating. Rein hoses are engineered to meet or exceed OEM standards, built from premium, heat-resistant materials that can take on extreme temperatures and system pressures without faltering. Each hose features factory-correct bends, fittings, and diameters for an exact, hassle-free installation—no cutting or forcing required. Whether you’re tackling a full cooling system refresh or chasing down a small coolant leak, this Rein kit provides everything needed to restore confidence and performance under the hood. Why choose this Rein radiator hose kit: Factory-level precision – Direct-fit replacements that deliver OEM-quality reliability. Built to last – Resists cracking, swelling, and chemical damage from daily heat cycling. Confidence restored – Prevents coolant loss, overheating, and on-road breakdowns. All-in-one upgrade – Includes upper and lower hoses for a complete system refresh. If keeping your BMW’s cooling system running tight and trouble-free is the goal, Rein brings the dependable quality and fitment you can count on—engineered to perform just like factory, mile after mile.

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Radiator Support Bracket

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T#:14122755

Part#: 17117514402

Special Order: No Guaranteed ETA

Sale - Save 12% $ 8.99

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06-29-2026

$ 7.88 USD

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Mounts to top of radiator bracket, 2 per vehicle.

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Rein BMW Cooling System Parts & Accessories for BMW E46 M3 S54 (1999-2005)

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OEM Rein Upper Radiator Hose - E46 M3

OEM Rein Lower Radiator Hose - E46 M3

E46 M3 Radiator Hose - Upper And Lower

OEM Rein Expansion Tank Cap - BMW E32 E34 E36 E38 E39 E46 & More ...

Rein Coolant Bleeder Screw CHW1575 - Priced Each

BMW Radiator Hose Kit - 11537830715

Radiator Support Bracket

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