| Cylinder Head Inspection |
Cylinder heads must be cleaned before any crack detection can be done.
Cast iron heads are cleaned in a hot tank with a caustic solution. Aluminum
heads are more delicate and are best cleaned with an appropriate degreaser
and a small wire brush.
Some sanding pads are too coarse for aluminum and should be avoided.
We usually call these pads "Cookies" and damage the surface when cleaning
gasket off aluminum. There are many softer brushes on the market that are
excellent for this application. Always practice care when dealing with
aluminum parts.The important thing is not to change the original surface.
Plastic scrappers and gasket softeners are often used to remove old gasket
material.
Magnetic particle inspection or Magnafluxing® is the process used with
ferrous or iron cylinder heads. A magnetic field is created using a permanent
magnet, cables, probes etc. while fine magnetic particles are applied to the
surface. A flux is created in the flaw or crack in the head and the fine particles
will gather showing any cracks missed during a visual inspection.
Aluminum heads are checked using a dye that penetrates into any cracks in
the cylinder head. The head surface is cleaned and the dye is sprayed on and
left for about 5 minutes. The surface is then wiped with clean shop rags and a
developer is applied. Any cracks will show up as red lines.
Pressure testing is done in a tank of water. All ports and passages are
covered with plates and inserts. About 30 psi. or 3 times coolant system
pressure is applied and any cracks will appear as tiny bubbles in the water.
Use a feeler gauge and a straight edge to check for warpage. Cylinder heads
will bow in the middle when overheated. Always check manufacturer’s
specifications for allowable clearances.
Cast iron heads are cleaned in a hot tank with a caustic solution. Aluminum
heads are more delicate and are best cleaned with an appropriate degreaser
and a small wire brush.
Some sanding pads are too coarse for aluminum and should be avoided.
We usually call these pads "Cookies" and damage the surface when cleaning
gasket off aluminum. There are many softer brushes on the market that are
excellent for this application. Always practice care when dealing with
aluminum parts.The important thing is not to change the original surface.
Plastic scrappers and gasket softeners are often used to remove old gasket
material.
Magnetic particle inspection or Magnafluxing® is the process used with
ferrous or iron cylinder heads. A magnetic field is created using a permanent
magnet, cables, probes etc. while fine magnetic particles are applied to the
surface. A flux is created in the flaw or crack in the head and the fine particles
will gather showing any cracks missed during a visual inspection.
Aluminum heads are checked using a dye that penetrates into any cracks in
the cylinder head. The head surface is cleaned and the dye is sprayed on and
left for about 5 minutes. The surface is then wiped with clean shop rags and a
developer is applied. Any cracks will show up as red lines.
Pressure testing is done in a tank of water. All ports and passages are
covered with plates and inserts. About 30 psi. or 3 times coolant system
pressure is applied and any cracks will appear as tiny bubbles in the water.
Use a feeler gauge and a straight edge to check for warpage. Cylinder heads
will bow in the middle when overheated. Always check manufacturer’s
specifications for allowable clearances.
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