Block‑Check Blue™

Common symptoms of a blown head gasket include engine overheating, white smoke from the exhaust, milky-looking oil (like mayonnaise under the oil cap), and coolant loss with no visible leak. While these are strong signs, the only way to be 100% sure without disassembling the engine is to test for exhaust gases in the cooling system using a combustion leak tester like LeakLogic's Block-Check Blue™.

A chemical combustion leak tester works by sampling the air/gas from your radiator or coolant expansion tank. The special blue test fluid inside the tester reacts to CO₂ (carbon dioxide), a gas present in your car's exhaust. If the fluid turns from blue to yellow, it confirms that exhaust gases are leaking into your cooling system, which is a definitive sign of a blown head gasket or cracked block.

Absolutely. LeakLogic Block-Check Blue™ is designed for both DIY home mechanics and professional garages. Its rapid 2-minute result time and clear colour change make it an ideal diagnostic tool for vehicle inspections, pre-purchase checks, and confirming a customer's reported symptoms, saving valuable workshop time.

Yes. Block-Check Blue™ is a universal formula that detects combustion CO₂ in any liquid-cooled petrol, diesel, or LPG engine.

Always test first. Head gasket sealants (like K-Seal or Steel Seal) only work if there is a confirmed leak. Using a tester like ours first confirms the problem, preventing you from wasting money on a sealant if the issue lies elsewhere. Testing also helps you understand if you have a small leak (where a sealant might work) or a major one that requires mechanical repair.