Coolant Hoses - Engine Bay

Water Hose that fits to the Water Pump part number 99610601156.
3-way to water pipe; original style with bleed nipple and straight flared hose end.

Fits:
Porsche 996 C2 / C4 1998-01 3.4L

This product supersedes Porsche's old part numbers:
- 99610625053
- 99610625054
- 99610625055
- 99610685000

Diagram ref no 18.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610685005

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This OE Match water hose connects the engine supply pipe to the main supply pipe on the specified rear-wheel-drive Porsche 996 C2 models. It forms part of the coolant supply circuit and provides a replacement connection when the existing hose is damaged or leaking.

Fits

• Porsche 996 C2 3.4L 1997–08/01
• Porsche 996 C2 3.6L 09/01–2005

Cars With Option Codes:

338 - Rear-Wheel Drive Application restriction: 

Diagram Ref No 1

Check fitment for your specific vehicle (model, year, engine) before ordering.

What Is This Part?
This is a connecting hose in the engine cooling system, joining the engine supply pipe and the main supply pipe. It forms the flexible section between those pipe connections, carrying coolant through that part of the circuit. Its condition and the condition of the adjoining connections both matter when investigating coolant loss. During replacement, inspect the pipe ends and retaining clamps so that a damaged connection is not left unresolved.

What Does This Part Do?

• Connects the supply pipes: Joins the engine supply pipe to the main supply pipe.
• Carries coolant: Provides a passage through this section of the cooling circuit.
• Forms the hose-to-pipe joints: Works with the associated retaining clamps to contain coolant at the connections.

Why Replace This Part?
Coolant hoses can deteriorate through repeated exposure to heat, coolant and their surrounding environment. Cracks, local softening, swelling or damage near the hose ends are reasons to assess replacement rather than simply tightening the clamps. Internal deterioration may also be present before an obvious external split appears.

Replace this hose if inspection confirms leakage or damage to its body or ends. Inspect the adjoining pipes and clamps at the same time: a leak at a connection does not automatically mean that the hose alone is responsible. Cooling-system work is a useful opportunity to check its condition, but removal by itself does not establish that replacement is necessary. 

When to Replace This Part?

• Confirmed leakage: Fresh coolant appears from the hose body or a damaged hose end.
• Cracks at the connections: Splits are visible around the areas secured by the clamps.
• Soft spots or bulging: Local changes in shape or firmness suggest deterioration.
• Surface damage: Rubbing or cuts have damaged the hose wall.
• Poor seating: A distorted or damaged hose end no longer sits correctly on its pipe connection.

Soft spots, cracks around fittings and bulges are recognised coolant-hose inspection points. Check the hose only when the cooling system has cooled. 

Where Is This Part Fitted?
Location: Between the engine supply pipe and the main supply pipe in the coolant supply circuit. Match these connection points and the rear-wheel-drive application before fitting.

Product Summary

• Product: Engine supply pipe to main supply pipe water hose.
• Brand: OE Match.
• Part reference: 99610664056.
• Additional supplied references: 99610664053 and 99610664054.
• Application restriction: Rear-wheel-drive Porsche 996 C2, I338 / M338.
• Purpose: Connects the two supply pipes within the coolant circuit.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610664056

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Water hose for cars with Tiptronic gearbox

Fits:
Porsche 996 C2 / C4 / C4S 1998-05 Tiptronic Gearbox

Click 'Zoom in' to see the diagram.
Diagram ref no 33.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610622266

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Water hose for cars with Tiptronic gearbox
High-quality OE Match coolant hose engineered to match the original Porsche specification for fit, flexibility, and durability. It is designed for the Porsche 996 (911) 1998–2005 with Tiptronic automatic transmission, and carries coolant within the engine’s cooling circuit to maintain proper operating temperatures. It installs directly in place of the original hose with no modification required, ensuring correct coolant flow and long-term service life.

Fits:
Porsche 996 C2 / C4 / C4S 1998 - 2005 Tiptronic Gearbox

Diagram ref no 33.

The Porsche 996’s water cooling system is responsible for regulating engine temperature under all driving conditions - from cold starts to high-speed touring. The water hose is a critical link in the coolant circuit, connecting key components such as the water pump, thermostat housing, radiator, and cylinder head.

Over time, heat cycling, pressure fluctuations, and environmental exposure cause hoses to age. Rubber can harden, swell, crack, or develop soft spots that lead to leaks, reduced coolant flow, or sudden failure. Because this hose operates under both thermal and pressure stress, deterioration can compromise cooling performance and increase the risk of engine overheating.

The water hose:
•  Carries pressurised engine coolant between major cooling system components
•  Maintains consistent coolant flow for stable temperature control
•  Withstands heat, vibration, and pressure from the engine’s cooling system
•  Helps prevent overheating and protects engine components

A compromised water hose can lead to:
•  Coolant leaks
•  Reduced heating efficiency
•  Engine overheating
•  Loss of pressure in the cooling circuit

Replacing old or degraded hoses with an OE Match water hose helps maintain coolant flow, preserves optimal engine temperatures, and prevents unexpected breakdowns due to hose failure.

Replace this water hose if you notice:
•  Visible cracks, soft spots, or swelling
•  Coolant leakage at hose ends
•  Unexplained engine overheating
•  During water pump or thermostat service
•  As part of preventative maintenance on higher-mile vehicles

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610622266

The product you are viewing cross references to these numbers

Water hose. Engine supply pipe to main supply pipe.

Fits:
Porsche 996 C2 1998-05
For Rear-wheel drive cars (I338)

Click 'Zoom in' for large parts diagram.
Diagram ref no 1

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610664056

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Water hose for cars with manual gearbox.

Fits:
Porsche 996 C2 / C4 3.4L Manual Gearbox

Click "Zoom in" to see the diagram.
Diagram ref no 33.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610622265

The product you are viewing cross references to these numbers

Water hose for cars with manual gearbox.
It provides reliable coolant flow between the engine and the heating/cooling system, maintaining optimal operating temperature and engine performance. Manufactured to match the original equipment’s material specification, bend geometry, this hose delivers a direct fit and factory-style durability.

Fits:
Porsche 996 C2 / C4 3.4L Manual Gearbox
Up to model year 2001

Diagram ref no 33

• Position on Vehicle: Located within the engine cooling circuit, this hose connects key engine cooling components and is mounted in the front engine bay.

• Cross-Reference / Alternative Numbers: Part number 996 106 222 65 (99610622265) — includes superseded numbers such as 99610622252, 99610622254, 99610622256.

• Applications: Ideal for when the original hose has become brittle, swollen, leaking or is due for renewal during engine service or cooling system overhaul.

The coolant hose is vital in maintaining proper engine temperature, protecting against overheating and ensuring the cooling system works as designed. A worn or damaged hose can lead to coolant leaks, engine overheating, poor heater performance or even severe engine damage. Replacing restores secure coolant flow, prevents failure and ensures your Porsche runs reliably.

When and why to replace:
• Visible cracks, bulging or brittleness in the original hose.
• Coolant leakage or low coolant level with no obvious external damage.
• Heating or cooling performance has reduced (e.g., slow warm-up or overheating).
• During scheduled cooling system service or when replacing other cooling system components.
• High-mileage vehicles where original hoses are showing signs of age and fatigue.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610622265

The product you are viewing cross references to these numbers

Water Hose.

Fits:
Porsche 996 Carrera 2/4 3.4L 1997>>2001
Porsche 996 Carrera 2/4 3.6L 2001>>2005
Porsche 996 Carrera 4S 3.6L 2001>>2005

Diagram Ref No 29

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610623351

The product you are viewing cross references to these numbers