Straight rubber radiator hose from 5mm to 102mm, heater hose in 16mm to 25mm, wire reinforced radiator hose in 13mm to 51mm, and moulded 45 and 90 degree rubber elbows in 10mm to 76mm - all EPDM to SAE J20 R3. Silicone equivalents are available across the same sizes if you want the upgrade.

EPDM rubber to SAE J20 R3, -30C to +120C, glycol rated for standard antifreeze mixes. That is the specification of virtually all original-equipment coolant hose and covers automotive, marine, agricultural and industrial cooling. It is not suitable for fuel or oil - hydrocarbons attack EPDM.

Order by internal diameter, matched to the outside diameter of the pipe stub the hose slides onto. Measure the pipe with vernier callipers rather than the old hose - hose stretches in service and reads large. If the two ends are different sizes you need a reducer rather than a straight hose.

Whenever the hose must resist vacuum or crushing - typically a long lower radiator hose that collapses as the water pump pulls against it, or a run that must bend tightly without kinking. The embedded steel helix holds the bore open where a plain hose would draw shut.

Use a moulded elbow for any real change of direction. Bending a straight hose closes up the bore, restricts flow and creates a stress point that will split eventually, usually without warning. Our rubber elbows come with 150mm legs each side, 300mm total, so there is plenty to trim.

Squeeze it. Hard and brittle, or spongy and swollen, both mean it is done. Look for surface cracking when you flex it and crusty residue or staining around the clips, which shows seepage. Replace on condition rather than waiting - coolant hose failures are sudden and always inconvenient.