What the Radiator Pressure Cap (1.0 bar) does
The radiator cap holds the cooling system under pressure, which raises the coolant's boiling point well above 100°C. When its seal weakens, coolant boils and escapes as steam, the level drops, and the engine overheats.
It is one of the cheapest parts on a generator and one of the most often overlooked. Replacing a tired cap at service is simple prevention.
Signs it needs replacing
- Coolant level dropping with no visible leak.
- Coolant overflowing from the expansion tank after running.
- Hardened, cracked or flattened rubber seal on the cap.
- Collapsed hoses after the engine cools (vacuum valve stuck).
Get the right part first time
Send us these on WhatsApp and our engineers will confirm the exact part before you pay:
- The pressure stamped on your current cap.
- A photo of the cap and filler neck.
Fitting notes
Never open a hot radiator — wait until the engine has cooled. Fit the cap with the same pressure rating as the original; a higher-rated cap can burst hoses or the radiator core.
Frequently asked questions
Can a radiator cap really cause overheating?+
Yes. Without pressure the coolant boils at a lower temperature and is lost as steam.
Can I fit a higher-pressure cap?+
No — use the rating specified for your cooling system. Too much pressure can damage hoses and the radiator.
How often should it be changed?+
Inspect it at every service and replace it when the seal is hard or cracked; many operators simply replace it yearly.