Cooling
Cooling System
Preventive maintenance is important. Aging E36 cooling-system parts can fail without much warning, potentially causing overheating and serious engine damage.
References
- Cooling System Maintenance
- Cooling System Bleeding Procedure
- Heater Hoses
- Coolant Specifications
- Cooling System Troubleshooting
Recommended Parts
| Component | Part number | Recommendation | Priority |
|---|---|---|---|
| Expansion tank kit | 17111723520KIT
|
Replace the expansion tank and upper hose. Check the coolant-level sensor and replace it if faulty. | High |
| Water pump | 11517527799
|
The Stewart high-performance pump is a premium long-term upgrade. | Medium |
| Thermostat housing | 11531722531
|
An aluminum housing is a practical replacement for the original plastic housing. | High |
| Thermostat | 11537511580 / 11537511083
|
Available in 88°C and 92°C versions. Confirm the correct temperature for your vehicle. | High |
| Radiator | 17111469179
|
Nissens is a good budget-friendly choice. Behr is a more expensive alternative. | High |
| Expansion tank cap | 17137639023 / 17117639022
|
Genuine BMW caps are available in 1.4-bar and 2.0-bar versions. | Medium |
| Upper radiator mounts | 17201719414
|
These secure the radiator clips and prevent the radiator from moving. | Medium |
Always verify part numbers using your VIN before ordering. Cooling-system configurations may vary by model, engine, production date, and market.
Expansion Tank
Expansion Tank Kit
Kit number: 17111723520KIT
The expansion tank is one of the most important preventive-maintenance items in the E36 cooling system. The plastic becomes brittle with age and will eventually fail.
When replacing the tank, inspect or replace:
- Expansion tank
- Upper expansion-tank hose
- Coolant-level sensor, if faulty
- Expansion-tank cap
- Radiator mounting clips and supports
Recommendation: Do not wait for visible cracking or leaking before replacing a very old tank.
Water Pump
Part number: 11517527799
The Stewart high-performance water pump is a high-quality but expensive upgrade. It is best suited for owners who plan to keep their E36 for a long time or want a premium cooling-system setup.
| Option | Cost | Best for |
|---|---|---|
| Standard OE-quality pump | Moderate | Normal street use and budget-conscious maintenance |
| Stewart high-performance pump | High | Long-term ownership, upgraded cooling systems, or demanding use |
Thermostat and Housing
Thermostat Housing
Housing part number: 11531722531
An aluminum thermostat housing is a practical upgrade over an aging plastic housing.
Important: The gasket supplied with some aftermarket housings may be lower quality. Use an OE-quality seal.
OE housing seal: 11531740437
Very little or no RTV should be necessary when the sealing surfaces and gasket are in good condition.
Thermostat Options
| Temperature | Part number | Notes |
|---|---|---|
| 88°C | 11537511580
|
Lower-temperature thermostat option |
| 92°C | 11537511083
|
Higher-temperature thermostat option |
| Thermostat gasket | 11531265084
|
Replace whenever the thermostat is removed |
Confirm the correct thermostat temperature for your engine and original vehicle configuration.
Radiator
Listed part number: 17111469179
Nissens is generally the more budget-friendly radiator choice while still being produced by a recognized manufacturer.
Behr/Mahle radiators are typically more expensive and are another good OE-style option.
Aluminum radiators: A full-aluminum radiator is usually unnecessary for a normal street-driven E36. Installation may be more involved, and the upgrade is generally more useful for track or heavily modified vehicles.
Expansion Tank Caps
| Cap rating | Part number | Notes |
|---|---|---|
| 1.4 bar | 17137639023
|
Lower-pressure genuine BMW cap option |
| 2.0 bar | 17117639022
|
Standard higher-pressure genuine BMW cap option |
Use the pressure rating specified for your vehicle and cooling-system configuration.
Upper Radiator Mounts
Part number: 17201719414
The upper radiator mounts hold the retaining clips in position and prevent the radiator from moving.
Check that:
- Both mounts are installed
- The clips are fully seated
- The rubber supports are not damaged
- The radiator does not move excessively
Heater Hoses
The heater hoses are located toward the rear of the engine and can be difficult to access. Replace any hose that is swollen, cracked, oil-soaked, hardened, or excessively soft.
Recommended Replacement Checklist
| Part | Inspect | Replace during overhaul |
|---|---|---|
| Radiator | Cracked necks, leaks, damaged fins, swelling | Yes |
| Expansion tank | Discoloration, cracks, leaking seams | Yes |
| Water pump | Bearing play, noise, leaking shaft seal | Yes |
| Thermostat | Incorrect temperature, sticking, overheating | Yes |
| Thermostat housing | Cracks, warping, corrosion, leakage | Yes |
| Radiator hoses | Swelling, cracking, softness, oil damage | Yes |
| Heater hoses | Cracking, hardening, leaks near firewall | Recommended |
| Expansion tank cap | Damaged seal or incorrect pressure rating | Recommended |
| Coolant-level sensor | False warnings or visible damage | If faulty |
| Radiator mounts | Missing clips, worn rubber, excessive movement | If damaged |
Installation Notes
- Allow the engine to cool completely before opening the cooling system.
- Clean all gasket and hose sealing surfaces before reassembly.
- Do not overtighten plastic fittings or hose connections.
- Use BMW-compatible coolant mixed with distilled water.
- Bleed the cooling system thoroughly after completing repairs.
- Check for leaks after the first full heat cycle.
- Recheck the coolant level once the engine has completely cooled.
Disclaimer: This page is intended as a general reference. Verify fitment, specifications, torque values, coolant type, and part numbers for your exact vehicle before beginning repairs.