Ford Transit Sport with suspected blown Head Gasket

Block Test on Head Gasket


This Ford Transit Van came to us at WV Autotech Ltd, Luton overheating and had trouble starting. We suspected it might be a blown head gasket so a block test was performed.

This tool contains a blue liquid chemical that reacts to hydrocarbons. The procedure is to pump the device containing the chemical with the car running for up to 45 minutes. If the chemical turns to a yellow/green colour then the head gasket is blown or the block is cracked.

The liquid changes colours when hydrocarbons enter the cooling system from a leaking head gasket. You will also be able to see bubbling in the device or reservoir from air entering the engine.


What does a Head Gasket do?

It seals the main engine block to the cylinder head using head bolts tightened to a specific torque specification. The gasket is meant to be a complete seal and is made up of thin metal plates together with a hard gasket composite. With constant expanding and contracting due to engine heat and the acidity of the coolant, the gasket can become weak and fail.

These gaskets must withstand the extreme pressures of the combustion process and hold radiator coolant which enables the transfer of anti-freeze from the engine block to the cylinder head. If the coolant is neglected it will turn acidic which eats away at the gaskets throughout the engine and especially the metal parts of the head gasket which seals the cylinder head to the block.

What are the symptoms of a blown Head Gasket?

A head gasket can fail at any time but will typically last between 110,000 and 160,000 miles depending on the engine condition, driving habits and engine maintenance.

When a head gasket fails it can do so in the following ways-

1. Coolant leaks into the engine oil
2. The coolant leaks outside of the engine
3. Mix combustion gasses into the radiator (cooling system)
4. Combustion transfers between two cylinders
5. Engine oil leaks outside of the engine

We replaced the head gasket for the customer complete with an oil filter and oil, a set of glow plugs and a timing chain kit; the customer was back on the road in their Ford Transit van within a week.

If you recognise any of the above symptoms, act quickly to prevent any further damage. Call us on 01582 969995 for advice or assistance.