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= 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 Hose..."

2026-07-28T03:28:48Z

Created page with "__NOTOC__ <div style="font-size:16px;line-height:1.55;max-width:1200px;"> = Cooling System = <div style="border-left:5px solid #1c69d4;background:#f3f7fb;padding:14px 16px;margin:12px 0 18px;"> '''Preventive maintenance is important.''' Aging E36 cooling-system parts can fail without much warning, potentially causing overheating and serious engine damage. </div> == References == * Cooling System Maintenance * Cooling System Bleeding Procedure * Heater Hose..."

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<div style="font-size:16px;line-height:1.55;max-width:1200px;">

= Cooling System =

<div style="border-left:5px solid #1c69d4;background:#f3f7fb;padding:14px 16px;margin:12px 0 18px;">
'''Preventive maintenance is important.''' Aging E36 cooling-system parts can fail without much warning, potentially causing overheating and serious engine damage.
</div>

== References ==

* [[Cooling System Maintenance]]
* [[Cooling System Bleeding Procedure]]
* [[Heater Hoses]]
* [[Coolant Specifications]]
* [[Cooling System Troubleshooting]]

== Recommended Parts ==

{| class="wikitable" style="width:100%;"
! Component
! Part number
! Recommendation
! Priority
|-
| Expansion tank kit
| <code>17111723520KIT</code>
| Replace the expansion tank and upper hose. Check the coolant-level sensor and replace it if faulty.
| style="text-align:center;" | '''High'''
|-
| Water pump
| <code>11517527799</code>
| The Stewart high-performance pump is a premium long-term upgrade.
| style="text-align:center;" | Medium
|-
| Thermostat housing
| <code>11531722531</code>
| An aluminum housing is a practical replacement for the original plastic housing.
| style="text-align:center;" | '''High'''
|-
| Thermostat
| <code>11537511580</code> / <code>11537511083</code>
| Available in 88°C and 92°C versions. Confirm the correct temperature for your vehicle.
| style="text-align:center;" | '''High'''
|-
| Radiator
| <code>17111469179</code>
| Nissens is a good budget-friendly choice. Behr is a more expensive alternative.
| style="text-align:center;" | '''High'''
|-
| Expansion tank cap
| <code>17137639023</code> / <code>17117639022</code>
| Genuine BMW caps are available in 1.4-bar and 2.0-bar versions.
| style="text-align:center;" | Medium
|-
| Upper radiator mounts
| <code>17201719414</code>
| These secure the radiator clips and prevent the radiator from moving.
| style="text-align:center;" | Medium
|}

<div style="font-size:13px;color:#555;margin-top:8px;">
Always verify part numbers using your VIN before ordering. Cooling-system configurations may vary by model, engine, production date, and market.
</div>

== Expansion Tank ==

<div style="border:1px solid #c7d3e0;border-left:5px solid #1c69d4;border-radius:6px;background:#fafcff;padding:15px;margin:12px 0;">

=== Expansion Tank Kit ===

'''Kit number:''' <code>17111723520KIT</code>

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.

</div>

== Water Pump ==

<div style="border:1px solid #c7d3e0;border-left:5px solid #1c69d4;border-radius:6px;background:#fafcff;padding:15px;margin:12px 0;">

'''Part number:''' <code>11517527799</code>

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.

{| class="wikitable" style="width:100%;margin-top:12px;"
! 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
|}

</div>

== Thermostat and Housing ==

<div style="border:1px solid #c7d3e0;border-left:5px solid #1c69d4;border-radius:6px;background:#fafcff;padding:15px;margin:12px 0;">

=== Thermostat Housing ===

'''Housing part number:''' <code>11531722531</code>

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:''' <code>11531740437</code>

Very little or no RTV should be necessary when the sealing surfaces and gasket are in good condition.

=== Thermostat Options ===

{| class="wikitable" style="width:100%;"
! Temperature
! Part number
! Notes
|-
| 88°C
| <code>11537511580</code>
| Lower-temperature thermostat option
|-
| 92°C
| <code>11537511083</code>
| Higher-temperature thermostat option
|-
| Thermostat gasket
| <code>11531265084</code>
| Replace whenever the thermostat is removed
|}

Confirm the correct thermostat temperature for your engine and original vehicle configuration.

</div>

== Radiator ==

<div style="border:1px solid #c7d3e0;border-left:5px solid #1c69d4;border-radius:6px;background:#fafcff;padding:15px;margin:12px 0;">

'''Listed part number:''' <code>17111469179</code>

'''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.

<div style="background:#fff5e6;border-left:4px solid #d97706;padding:11px 13px;margin-top:12px;">
'''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.
</div>

</div>

== Expansion Tank Caps ==

<div style="border:1px solid #c7d3e0;border-left:5px solid #1c69d4;border-radius:6px;background:#fafcff;padding:15px;margin:12px 0;">

{| class="wikitable" style="width:100%;"
! Cap rating
! Part number
! Notes
|-
| 1.4 bar
| <code>17137639023</code>
| Lower-pressure genuine BMW cap option
|-
| 2.0 bar
| <code>17117639022</code>
| Standard higher-pressure genuine BMW cap option
|}

Use the pressure rating specified for your vehicle and cooling-system configuration.

</div>

== Upper Radiator Mounts ==

<div style="border:1px solid #c7d3e0;border-left:5px solid #1c69d4;border-radius:6px;background:#fafcff;padding:15px;margin:12px 0;">

'''Part number:''' <code>17201719414</code>

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

</div>

== 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.

<div style="text-align:center;margin:16px 0;">
<span style="display:inline-block;border:1px solid #1c69d4;border-radius:5px;background:#f3f7fb;padding:9px 16px;">
'''[[Heater Hoses|View the E36 Heater Hose Guide]]'''
</span>
</div>

== Recommended Replacement Checklist ==

{| class="wikitable" style="width:100%;"
! Part
! Inspect
! Replace during overhaul
|-
| Radiator
| Cracked necks, leaks, damaged fins, swelling
| style="text-align:center;" | Yes
|-
| Expansion tank
| Discoloration, cracks, leaking seams
| style="text-align:center;" | Yes
|-
| Water pump
| Bearing play, noise, leaking shaft seal
| style="text-align:center;" | Yes
|-
| Thermostat
| Incorrect temperature, sticking, overheating
| style="text-align:center;" | Yes
|-
| Thermostat housing
| Cracks, warping, corrosion, leakage
| style="text-align:center;" | Yes
|-
| Radiator hoses
| Swelling, cracking, softness, oil damage
| style="text-align:center;" | Yes
|-
| Heater hoses
| Cracking, hardening, leaks near firewall
| style="text-align:center;" | Recommended
|-
| Expansion tank cap
| Damaged seal or incorrect pressure rating
| style="text-align:center;" | Recommended
|-
| Coolant-level sensor
| False warnings or visible damage
| style="text-align:center;" | If faulty
|-
| Radiator mounts
| Missing clips, worn rubber, excessive movement
| style="text-align:center;" | 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.

<div style="border-top:1px solid #ccd5df;margin-top:24px;padding-top:12px;font-size:13px;color:#555;">
'''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.
</div>

</div>

Cooling - Revision history