How an aluminum head is pressure tested for cracks.
The subject head is a 5sfe Toyota DOHC
The procedure will be the same for any head.
First all the old gasket material has to be removed around all the water ports in the head.
Head gasket, thermostat, any ports that flow water.
This procedure is usually done after the head has been checked for warp.
Once that is done the head is placed in the pressure testing fixture.
Next the proper test plate is selected from the stack.
This plate fits this head.
See how it covers all the water ports on the head deck.
Next the clamping bars are placed over the head and tightened down.
any other water ports are blocked of with plates or plugs. One plate has an air fitting so compressed air can fill the water jacket.
On the right end of the head.
Compressed air fills the water jacket, appox 30psi.
Soap water is then sprayed over the head, Looking for bubbles from a crack.
Great care is used in the combustion chambers, and all runners, along with the top of the head.
This head was good and showed no signs of cracks for coolant to leak from.