Where is the head gasket in a 1990 buick skylark and how do you knopw if its bad?

Loss of power and a pinging noise while the engine is under a load are also signs of a leaking head gasket. Make sure to have the head checked by a machine shop for cracks and flatness before you reinstall it. Also this is a good time to flush the coolant out of the engine. You will need a torque wrench and the proper torque sequence with your new head gasket as well. I did this job on my Skylark (2.5 Irond Duke) and I found it much easier to remove the exhaust pipe off the manifold and disconnect all the linkage, fuel and coolant lines from the intake manifold and remove the entire head, intake, and exhaust manifold in one piece. Of course this is just personal preference. Otherwise you will have to buy all new gaskets for the exhaust manifold and the intake manifold and spend an hour scraping the old gaskets off. These engines also have a hydraulic valve train that requires torquing the rocker arms down. It is a good idea to remove the load from the rockers first before torquing. This is accomplished by cranking the engine over by hand thereby moving the camshaft to provide the maximum slack in the rocker arm your trying to torque. I torqued mine to around twenty foot pounds. Anywhere from sixteen to twenty foot pounds should be fine.

Gasket is between cylinder head and engine block. If u have oil in the coolant or vice versa, or overheating then u most likely have a bad head gasket