FAQ32 - How do I ensure my head gasket seals properly?
For years, we've heard from people who failed to install their head gaskets properly, blaming it on aftermaker makers, no matter the source: British, American, Japanese, Taiwanese, Chinese, Indian etc. On one forum, we noted the complaint of someone who experienced constant failure and fluid loss even after installing OEM gaskets. Restoration and refurbishment of an old engine is not as easily done as some may think.
One of many reasons for the failure is not using anti-seizure compound on the head and other bolts. Head bolts stretch over the years, jam up and won't draw down on a dry fit. The heads are aluminum and bolts steel, and both have a far different rate of expansion. If the head bolts have distorted too far out of pitch, they simply have to be replaced in order for the head to be drawn down over the gasket. The heat and flame resistant ring in the gasket positioned just at the top of the cylinder bore must be sufficiently crushed to allow the gasket material to be properly sandwiched and isolated from the intense heat of the igniting cylinder.
The problem gets worse over the years with constant contraction and expansion, and unless torquing is done slowly, careful and at least a half a dozen rotations, the heads will not be pulled down to make a perfect seal.
Shaving the heads is improper to do and will add to the overall distortion. Only milling by a highly skilled technician will get a perfect surface. Both heads and engine blocks MUST be done at the same time to get a matching result. There are specific tests and measurements to confirm the correct result. For this, you will have to engage the services of a skilled millwright.
The material of our head gaskets are no different to those supplied by Vesrah, NP and KP, all of whom are Japanese makers, using the newest materials and technology, which are vastly different from the material used and specified by Honda 30 to 40 years ago. We are going to see differences using OEM, considering that Honda themselves may still be using up vast stocks that they bought years ago.
We found an excellent article by Federal Mogul's Technical Education Center that will prove that slapping in a head gasket is not a process that everyone should or can undertake: