Losing Coolant With No Obvious Leak? Here’s How to Find It
Small leaks can appear only when the system is pressurised. A cold-system pressure test helps expose hoses, caps, radiators and housings without running the engine.
01
Choose a pressure tester by adaptor coverage
Starter option
Sealey VS0012 4-Piece Kit
A compact kit with two adaptors—ideal only where those fittings match the vehicle.
View VS0012 →
Broader coverage
Sealey VS0014 13-Piece Kit
A wider adaptor selection and pressure gauge for working across more applications.
View VS0014 →
Workshop pick
Laser 5614 Pressure Test Kit
A multi-application kit aimed at radiator and cooling-system leak diagnosis.
View Laser 5614 →
20-piece option
Sealey VS001 Tester Kit
Provides broader workshop coverage in a storage case for multi-vehicle use.
View VS001 →
02
Pressure-test safely
- Let the engine cool completely—never open a hot pressurised system.
- Inspect the expansion tank, cap, hoses, radiator seams and housings first.
- Fit the correct adaptor securely.
- Pump only to the lower of the vehicle or tester’s stated limits.
- Watch the gauge and inspect methodically for escaping coolant.
- Release pressure safely before removing the tester.
03
No visible external leak?
- Check beneath undertrays
- Inspect the heater circuit
- Recheck the cap and adaptor seal
- Look around the water pump
- Investigate repeated overheating
- Seek diagnosis for suspected internal loss