Coolant Hoses

Coolant hoses link engine, radiator, heater and expansion tank, and they flex every time the engine moves on its mounts. A silicone hose kit replaces the factory rubber hoses with reinforced silicone, which resists heat ageing far longer. Listed here are vehicle-specific radiator hose kits and more complete coolant hose kits.

Rubber hoses age from the inside: heat and coolant chemistry harden the inner layer until it cracks, often out of sight under a clamp. In a silicone hose, fabric reinforcement inside the wall carries the pressure, while the silicone stays flexible through years of heat cycles. Silicone swells and weakens in contact with oil and fuel, though, so it belongs on coolant and air lines only.

The lower radiator hose feeds the water pump inlet, the point of lowest pressure in the system. At high revs a weak hose there can be sucked flat and starve the pump, so wall strength matters on that side as much as on the pressure side.

The titles show what each kit covers.

• Radiator hoses or more: radiator hose kits replace the main upper and lower hoses. Broader silicone kits add smaller coolant hoses, so more of the ageing rubber goes in one job.
• Engine swaps: swap kits route coolant between a different engine and the radiator position of the original car.
• Colour: blue, black and red, plus matte black. The colour has no effect on function.
• Induction hoses: some kits serve the intake side rather than the coolant, so read the title before ordering.

Use clamps made for silicone: smooth-band or constant-tension clamps spread the load, while a perforated worm-drive band can cut into the soft surface. Seat each hose fully, place the clamp just behind the bead on the pipe, and re-check the tension after the first few heat cycles, as silicone settles under the clamp.

Refill with coolant mixed to the engine maker’s specification, open any bleed screws, and run the engine with the heater on full until the thermostat opens. Squeeze the upper hose to push out trapped air, then top up once the engine has cooled. At each service, look for swelling, soft spots near the ends and weeping at the clamps.