Q&A

 Master

The 22RE engine is a great engine. I would remove the valve cover and adjust the valve clearances and with the valve cover off I would carefully inspect the timing chain guides, they get brittle and brake. I have seen the guide brake, and the slackness in the chain wear a hole allowing coolant and oil to mix, at that point the chain cover has to be removed. The coolant loss I would pressurize the cooling system using a pressure tester and look for external coolant loss if no loss is found do what is called a block check. The most accurate way to test for a blown head gasket on a gasoline engine is to test for the presence of carbon monoxide in the cooling system. Snap-On, Matco (part # CO 2000), and Napa sell a tool to check to carry out this test. Another link to a supplier of this tool is http://www.etoolcart.com/combustion-leak-detector-lis7550.... Carbon Monoxide is only present if there is a blown head gasket or cracked cylinder head. http://www.arrowheadradiator.com/head_gasket_or_combustio... I think the napa part number 700-1006. http://www.blockchek.com/instructions.htm . Signs of a blown head gasket are coolant loss (frequently have to top up the coolant level of the engine without seeing an obvious leak), experiencing over heating or rough engine running or the presence of white sweet smelling steam from the exhaust. A badly blown head gasket may allow engine coolant and oil to mix.
A last thought on the engine tapping sound, with the engine running slacken the valve cover hold down bolts I have seen some aftermarket V/Cover gaskets allow the rockers to contact the inside baffle in the valve cover, with the valve cover off look for indentations on the oil baffle in the valve cover, after that inspect for rocker wear..Love to hear what you find it may help someone else!