Cylinder Heads

 Call us for expert advice and a quotation for your engine machining requirements.

Pressure Testing

All pressure testing for cylinder heads is carried out on our dedicated Delta pressure testing rig.


Pressure testing can be viewed as an insurance policy which, if faults are discovered, will prevent losing time and money working on a damaged head which might then be wasted if the head is found to be unserviceable at some later stage.


While it is good practice to pressure test any cylinder head to ensure integrity prior to investing time and money on more expensive machining work, this becomes more critical following any serious overheating related failure.  Cylinder heads which have suffered serious overheating issues are far more likely to have unseen problems which the pressure testing process will highlight.  Equally, any head showing symptoms related to water loss or oil/water cross contamination in service (especially when no obvious visible cause is evident) is a definite candidate for pressure testing.


Heads to be tested are mounted on the rig where all open water passages on the head gasket surface are covered using dedicated pads.  These pads are in turn covered with cross bars which spread the clamping forces evenly when the block is clamped down for testing.  The special air inlet pad is connected to the air feed at this stage.


Any water outlets on the end or side faces of the head including water pump or thermostat apertures are also covered using similar pads which are secured in place with specially designed screw clamps which locate in the framework of the rig.


Other holes, for example where sensor switches are fitted, can be blocked off using the original component or with screw in blanking plugs.


Once all water passages are blocked, an air inlet tap is turned on to fill the head with compressed air at pressures up to 60psi.  When full pressure is reached, the tap is then closed again and the pressure gauge monitored over a period of time for signs of pressure drop.  Falling pressures indicate a leak from within the casting which will then require further investigation.


Leaks can be detected using a bubble solution which, when applied, will foam around the area where any air is escaping from the casting indicating a leak at that point.


Pressure testing on cylinder heads will show up faults including external cracks in the casting, cracks in internal areas such as inside the cam or valve chest area, porosities in valve ports or under valve seat inserts and leaks from core plugs all of which would not be evident from other means.


On diesel cylinder heads with high pressure diesel systems the internal fuel rail drillings can also be tested to eliminate this area as a possible cause for fuel/water cross contamination.

Call us for expert advice and a quotation for your engine machining requirements.