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Porsche // 991 (911) MK2 2016-2019 // 991.2 Carrera 2 3.0L (370 Bhp) 2016-19
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Left Hand Coolant Hose for Centre Radiator
The left hand coolant hose is an essential cooling system component used on the Porsche 718
Boxster and 718 Cayman. This hose connects to the centre radiator and allows
coolant to circulate between the radiator and the engine cooling system.
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Diagram Ref No 6
Modern Porsche engines rely on efficient coolant circulation to maintain safe operating temperatures, especially during spirited driving or extended high-load conditions. A properly functioning coolant hose ensures consistent coolant flow and helps protect the engine from overheating.
What This Coolant Hose Does
The cooling system on the Porsche 718 uses multiple radiators positioned at the front of the vehicle to dissipate heat from the engine coolant. The centre radiator improves cooling efficiency under higher loads.
The left hand coolant hose helps:
• Carry coolant between the
centre radiator and the main cooling circuit
• Maintain stable engine operating temperatures
• Ensure efficient heat dissipation through the radiator system
• Support reliable cooling during fast road or track driving
Without proper coolant flow, engine temperatures can rise quickly, increasing the risk of overheating and engine damage.
Why Coolant Hoses Fail
Coolant hoses operate under constant pressure and high temperature conditions. Over time, materials degrade and may begin to fail.
Common causes of hose failure include:
Heat ageing
Continuous heating and cooling cycles can cause rubber hoses to harden or
crack.
Pressure fatigue
The cooling system operates under pressure, which can weaken older hoses and
cause swelling or splits.
Coolant contamination
Old coolant or contaminants may degrade hose materials internally.
Mechanical wear
Movement, vibration or contact with nearby components can damage the hose over
time.
Symptoms of a Failing Coolant Hose
• Visible coolant leaks under
the vehicle
• Sweet coolant smell from the front of the car
• Low coolant warning messages
• Engine temperature rising unexpectedly
• Visible cracking, swelling or soft spots on the hose
Replacing worn hoses prevents sudden coolant loss and protects the engine from overheating.
Why You May Need to Replace This Hose
Prevent Cooling System Leaks
Replacing ageing hoses ensures the cooling system remains properly sealed and
pressurised.
Maintain Engine Cooling
Performance
Reliable coolant flow is essential for maintaining correct operating
temperatures in high performance engines.
Protect Engine Components
Coolant loss can lead to overheating, which may cause severe engine damage if
left unresolved.
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For cars with centre radiator (I153)
Click 'Zoom in' for large parts diagram.
Diagram ref no 6
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Diagram ref no 7
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Diagram ref no 19
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This OE Match top left water coolant radiator hose is a replacement feed hose for Porsche 982, 991.2, and GT4 models. It is designed to match the original-style fitment and function, helping maintain correct coolant flow through the vehicle’s cooling system.
Please note: Requires new jubilee clip. Available separately - part number 99951249900
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Diagram ref no 19
The top left radiator feed hose carries coolant through the radiator circuit, helping regulate engine temperature and support efficient heat transfer. A secure, leak-free coolant hose is essential for maintaining correct cooling system pressure and protecting the engine from overheating.
Functions
• Replaces the top left coolant radiator feed hose
• Carries coolant through the radiator and engine cooling circuit
• Helps maintain correct engine operating temperature
• Supports cooling system pressure and coolant circulation
• Helps prevent coolant leaks, pressure loss, and overheating
• Replaces cracked, swollen, split, leaking, or aged original hoses
• OE Match replacement for cooling system repair and maintenance.
Why Replace This Part?
Coolant radiator hoses are exposed to constant heat, pressure, coolant additives, vibration, and age-related wear. Over time, the hose can harden, soften, swell, crack, split, or leak. A failing hose may cause coolant loss, low coolant warnings, overheating, steam, or reduced cooling system reliability. Replacing the hose helps restore dependable coolant circulation and protects the engine from heat-related damage.
When to Replace This Part
• The radiator hose is cracked, swollen, brittle, soft, or split
• Coolant leaks are visible around the hose or connection points
• The engine is overheating or coolant level is dropping
• Low coolant warnings appear
• The hose has become loose, contaminated, or damaged
• The radiator, water pump, thermostat, or coolant pipes are being serviced
• Preventative replacement is being carried out during cooling system maintenance.
Where it fits on the car
This hose fits in the top left radiator feed position within the cooling system on Porsche 982, 991.2, and GT4 models. It connects according to the factory coolant hose routing and supports coolant flow through the radiator circuit.
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