What are the water pipes that connect the water pump to the car?

1. Water pump inlet pipe (low pressure side water pipe)

Function: deliver the low-temperature coolant of radiator or expansion tank to the inlet of water pump to provide cooling medium for circulation.

Structural features:

Usually located at the front or side of the water pump, it is connected with the downcomer of the radiator or the liquid outlet of the expansion tank.

The diameter of the pipeline is larger to reduce the flow resistance and meet the suction demand of the pump.

Most of the materials are high-temperature resistant rubber or silica gel, and the interior often contains woven fiber layers to enhance the compression resistance and vacuum deformation resistance.

2. Water pump outlet pipe (high pressure side water pipe)

Function: transport the pressurized coolant from the outlet of the water pump to the water channel of the engine block to realize heat absorption.

Design points:

Directly connected to the water inlet of the engine block, it bears high pressure (usually 1.5~3 bar).

Some models adopt metal (aluminum or steel) and rubber composite structure to improve high temperature and high pressure resistance.

The pipeline route needs to avoid high-temperature components (such as exhaust manifold) to reduce the risk of coolant vaporization caused by thermal radiation.

3. Heating system circulating water pipe

Function: Branch some coolant to the heater core in the car to provide heat source for air conditioning and heating.

Working logic:

The flow rate is controlled by electromagnetic valve or mechanical valve, which is connected in parallel with the outlet of water pump.

After the coolant flows through the warm air core to dissipate heat, it re-enters the water inlet pipe of the water pump or the main circulation loop through the return pipe.

4. Bypass pipe (bypass pipe)

Function: When the thermostat is closed or cold started, a small circulation path is established to speed up the engine warm-up and prevent the water pump from cavitation.

Typical configuration:

Connect the outlet of the water pump with the thermostat housing or the water return port of the cylinder head to form a short-path circulation.

The pipe diameter is small, and some models integrate one-way valves or flow-limiting holes to adjust the bypass flow.

5. Expansion tank connecting pipe

Function: Balance the pressure of the cooling system, accommodate the coolant overflowing due to thermal expansion, and replenish it to the main circuit after cooling.

Interface location:

It is usually led out from the bottom of the expansion tank and connected to the water inlet pipe of the pump or the backwater end of the radiator.

An overflow valve or vent hole may be integrated in the pipeline to exhaust the gas in the system.

6. Turbocharger/transmission cooler pipeline (specific model)

Extended function: In high-performance or high-load vehicles, the water pump may provide cooling liquid for turbocharger intercooler or gearbox oil cooler through branch pipes.

Design features:

The pipeline is independent of the main circulation and equipped with additional control valves to distribute the flow as needed.

The material needs to withstand higher temperatures (such as silicon-based composite materials) and adopts double-layer heat insulation structure.

Technical parameters and maintenance points

Material standard: the water pipe shall meet the requirements of SAE J20 or ISO 4081, with temperature resistance ranging from-40℃ to 150℃ and bursting pressure ≥5 bar.

Failure mode: Common aging is cracking, expansion or joint leakage, so it is necessary to check the hardness of hose and the fastening state of clamp regularly.

Upgrade plan: high-performance modification is often replaced by silicone hose to improve durability and reduce the risk of tube explosion.

summary

The water pipe network connecting the water pump is the key carrier for the efficient operation of the cooling system, and its design needs to take into account the hydrodynamic efficiency, thermal management requirements and space layout restrictions. Through accurate flow distribution and pressure control, each pipeline ensures the optimal temperature control of the engine under all working conditions, and at the same time provides extended functional support for auxiliary systems (such as warm air and turbine cooling). Regular maintenance and pipeline condition monitoring can effectively prevent cooling system failure and prolong engine service life.