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BMW Cooling System Parts & Accessories for BMW 5 Series E34 (1987-1995)

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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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Basic Cooling System Service Kit - E34 525i M50 2.5L

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T#:557231

Part#: E34525BCKT

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$ 231.24 USD

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Just like the rest of your vehicle's major systems, the cooling system must also be addressed periodically to ensure proper cooling and component reliability. Plastic and rubber components become brittle and prone to splitting or cracking after long periods of heating and cooling cycles, especially in colder climates! The coolant itself can degrade or become contaminated, leading to potential corrosion or freezing issues. Finally, thermostats and sensors can fail completely, preventing proper cooling and/or coolant temperature readings to become inaccurate.

To make sure you are not left stranded on the side of the road with an overheated engine, we have put together this Basic Cooling System Service kit. This kit contains all of the most-likely-to-fail components, giving you peace of mind knowing your engine will continue to run cool for another 60,000+ miles.

See kit contents below for all included components.

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Thermostat Replacement Kit - E28, E30, E34 M20B25/27

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T#:41289770

Part#: 11531730470TKT

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$ 73.38 USD

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This BMW Thermostat Replacement Kit is the go-to choice for preserving the performance and reliability of your classic M20-powered BMW—keeping your engine running cool and smooth mile after mile.

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Water Pump - E34 530i 540i E32 740i/il

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T#:338251

Part#: 11510007042X

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Starting at $ 470.99 USD

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Starting at $ 470.99 USD

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Don't take your car's cooling system for granted! One of the biggest weak points is the cooling system. Replacing your waterpump will go a long way for keeping your car on the road and operating properly.

This item fits the following BMWs:
1992-1995 E34 BMW 530i 540i
1992-1994 E32 BMW 740i 740ill

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Rein Thermostat - 88ï¿½C - E30, E34, E36, Z3

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T#:591800

Part#: 11537511580

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$ 36.09 USD

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Common point of failure in the cooling system.

OEM Rein Throttle Body Return Hose - E34 525i

For vehicles with a production date from 03/1991

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T#:379743

Part#: 11531738054

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$ 58.89 USD

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Over time, coolant hoses begin to get brittle and are susceptible to cracking and splitting. Replace your cracked or leaking coolant hose to prevent further leaks and potentially catastrophic failure.

Rein Radiator Hose - Upper - E32, E34

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T#:6960

Part#: 11531722682

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08-31-2026

$ 60.79 USD

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BMW ENGINE WATER HOSE 11531722682.--

This item fits the following BMWs:
BMW 5 Series -535i
BMW 7 Series - 735i, 735iL

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Rein Thermostat O-Ring (60 X 3.5 mm) - E28 E30 E32 E34 E36 E39 Z3 E23...

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T#:591144

Part#: 11531265084

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08-31-2026

$ 1.95 USD

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This O-ring seals the thermostat to the cylinder head.

Rein Water Pump O-Ring (Small) - E32, E34, E38, E39

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T#:379680

Part#: 11531710055

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08-31-2026

$ 1.93 USD

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When it comes time to replace the water pump, be sure to replace all the O-Rings associated with it to ensure that your car stays leak free. If you are experiencing leaking issues, be sure to inspect these rings, as they might have worn down. This specific ring is used when replacing water pump on cooling pipe to the water accumulator. There are two per car.

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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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08-31-2026

$ 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 Expansion Tank Hose - E12, E21, E23, E24, E28, E30, E32, E34 ...

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T#:19431

Part#: 17121712736

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08-31-2026

$ 13.29 USD

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VENT HOSE 17121712736 Manufactured by CRP

Water Pump to Thermostat Cooling Hose - E30 E34 E28

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T#:6917

Part#: 11531287651

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$ 10.44 USD

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Replace your cracked or leaking coolant hose with this radiator coolant hose that goes from the waterpump to the thermostat on cars with the M20 engine. We recommend inspecting cooling system hoses for dry rot / cracks yearly.

This item fits the following BMWs:
1984-1991 E30 BMW 325e 325es 325i 325ic 325is 325ix
1982-1988 E28 BMW 528e
1989-1990 E34 BMW 525i

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Rein Coolant Bleeder Screw CHW1575 - Priced Each

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T#:591955

Part#: 17111712788

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$ 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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Rein Water Hose (Right Outlet) - E32 E34

Also use- (Qty.) (1) 17 21 1 723 943 O-Ring. ¦ Right

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T#:593082

Part#: 17221728944

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$ 27.54 USD

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Transmission Oil Cooler to Water Manifold

OEM Rein Coolant Hose - E34 525i M20

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T#:6955

Part#: 11531720678

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$ 11.39 USD

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Over time, coolant hoses begin to get brittle and are susceptible to cracking and splitting. Replace your cracked or leaking coolant hose to prevent further leaks and potentially catastrophic failure.

This item fits the following BMWs:
BMW 5 Series - 525i, 525i Wagon

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OEM Rein Lower Radiator Hose - E34 525i

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T#:6962

Part#: 11531722852

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$ 12.34 USD

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Over time, coolant hoses begin to get brittle and are susceptible to cracking and splitting. Replace your cracked or leaking coolant hose to prevent further leaks and potentially catastrophic failure.

Rein Coolant Hose - E28, E30, E34

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T#:379671

Part#: 13541719966

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$ 5.80 USD

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Thermostat to throttle housing

OEM Rein Coolant Hose - E32 E34

For vehicles with production date from 03/1995

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T#:6970

Part#: 11531741405

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$ 14.24 USD

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Over time, coolant hoses begin to get brittle and are susceptible to cracking and splitting. Replace your cracked or leaking coolant hose to prevent further leaks and potentially catastrophic failure.

This item fits the following BMWs:
BMW 5 Series - 530i, 530i wagon /540i
BMW 7 Series - 740i, 740iL

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Rein Expansion Tank Cap - E30, E34

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T#:592018

Part#: 17137639023

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$ 14.24 USD

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1.4 Bar pressure

Coolant Expansion Tank With Cap - 17111712835

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T#:46616014

Part#: EPK0012

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$ 27.65 USD

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The coolant expansion tank provides a place for excess fluid as coolant expands and contracts with temperature changes. Constant exposure to these extremes can cause the tank to crack, break, or suffer damage to its nipples or mounting points. To keep your cooling system sealed and functioning properly, any damaged tank should be replaced.

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Rein Heater Hose - E32, E34

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T#:20514

Part#: 64211390935

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$ 12.34 USD

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HOSE F WATER VALVE AND LEFT 64211390935 Manufactured by CRP

Rein Thermostat 80C - E30 325e, E28 535i, E24 633CSi

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T#:34114243

Part#: 11531710953

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$ 18.99 USD

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Thermostat 80C is a crucial component for controlling the temperature in BMW engines, ensuring optimal performance and protection. Designed to open at 80°C, this thermostat helps your engine reach its ideal operating temperature quickly while preventing overheating. Engineered specifically for BMW vehicles, the Thermostat 80C ensures precise temperature regulation, enhancing both engine efficiency and longevity. Available at Turner Motorsport, this direct-fit replacement offers easy installation and reliable performance.

Designed for BMW engines for a perfect fit
Opens at 80°C to regulate coolant flow and maintain optimal temperature
Prevents overheating and improves engine efficiency
Manufactured from high-quality, durable materials for long-lasting use
Direct-fit replacement ensures hassle-free installation
Enhances overall engine performance and longevity

The Thermostat 80C from Turner Motorsport is the perfect choice for BMW owners looking to maintain optimal engine temperature, ensuring smooth operation and extending the life of their vehicle.

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