Diagnosing External Fluid Leaks
Hino has a redesigned cylinder head gasket for model years 2005-2015 equipped with a J08 engine. Customers may complain of an external oil or coolant leak. When diagnosing these trucks pay attention to the cylinder head to engine block mating service. Always perform a pressure test when looking for an external coolant leak. When looking for external coolant leaks under pressure look on the exhaust side of the cylinder head mating surface. If you determine the leak is coming from cylinder head mating surface it will be necessary to replace the cylinder head gasket with an OEM redesigned cylinder head gasket.
When the complaint is an oil leak the use of engine oil dye and a black light may be a useful tool to pinpoint the exact location. When looking for an oil leak pay attention to the exhaust side of the cylinder head to engine block mating surface. If you determine the leak is cylinder head to engine block mating surface it will be necessary to replace the cylinder head gasket with a redesigned OEM cylinder head gasket.
The use of aftermarket parts is not recommended. Cylinder head gasket replacement procedure can be found in our information packet category at trucktechhelp.com.