GM 12557767 Engine Exhaust Manifold Assembly

Pull the cable off the negative battery terminal. Lift the car up, then find places to support it with jackstands. Take off the pan that guards against water damage below the car's engine compartment front. Remove the engine cooling fans and the radiator. Take the front oxygen sensor and EGR pipe off the parts connecting the coolant housing with the exhaust housing and exhaust tube. Change the EGR pipe because its crush seal can't be reused after taking it apart. Remove the air tube that runs to the exhaust manifold, take off the air valve and the bracket connected to it. Take off the exhaust crossover pipe from three places: the exhaust manifold, the left side coolant heater (if your car has one), and the oil dipstick tube. Put penetrating oil in and around the front exhaust manifold's connecting fasteners. Allow the oil to soak for a while before removing the manifold from the cylinder head. Unplug the connector that supplies electricity to any rear oxygen sensor into the car's engine. Place jackstands under the vehicle, lift it, and make sure it stays stable. Take out both the exhaust Y-pipe from the catalytic converter and exhaust crossover pipe. caretakerspraying penetrating oil on both the right side coolant heater and the exhaust manifolds that hold them to the cylinder heads. Look for breaks or harm in the manifolds and their attached parts before installation. Scrub the manifolds and cylinder head with a scraper to eliminate coat of old gasket material and carbon buildup. Ask an automotive machine shop to test the manifolds for unevenness, and let them fix them if they need it. Put fresh gaskets onto the screws that connect the cylinder head to the engine. Steadily place the manifolds and put their mounting nuts onto each one by hand. Start your tightening process from the middle of the nut, and twist to the recommended torque. Install the front engine mount and bracket. First put the radiator back, followed by the engine cooling fans, then fill your car's cooling system. Reinsert all parts backward, putting fresh gaskets in between exhaust connections during assembly. Run the engine and check for exhaust leaks. Connect the Y-pipe of the exhaust to the catalytic converter. Put the shaft that connects the steering gear with the steering system in place. Put back all other parts by undoing how you took them out first, replace exhaust gaskets with new ones when linking the pipes together. Reput your cooling fluid, start the car, and make sure there are no exhaust dripping out.

Before critically removing the front exhaust manifold one has to disconnect the cable of the negative terminal from the battery. Lift the car and snugly put jackstands under the car then, Pop the lower splash pan if it is located below the front of the engine compartment, remove the engine cooling fans, the radiator. Before any procedure for the 1999 models, disconnect the air filter housing, left and right torque struts and the front engine mount nuts while there is a support from the floor jacks of the engine/transaxle subframe. The front engine mount brace has to be removed by lifting the engine/transaxle assembly carefully. Soak the exhaust manifold and exhaust flange bolts with penetrating oil and let it to set in, than unscrew the exhaust Y-pipe and separate it from the catalytic converter as well as remove the front oxygen sensor. Take off the rear alternator bracket, and exhaust flange nuts from the exhaust manifold, the exhaust crossover pipe also needs to be unbolted from the exhaust manifold from the cylinder head. For 2000 and later models, also remove the front oxygen sensor and the EGR pipe from the coolant crossover housing and exhaust crossover pipe, and note that the EGR pipe has a crush seal which must be replaced. If equipped, disconnect the left side coolant heater assembly, the oil dipstick tube, then spray the penetrating oil on the front exhaust manifold and un bolt it. Trim the rear exhaust manifold and unplug the connector for the rear oxygen sensor; lift the vehicle and safely support it on jack stands. For 1999 models remove exhaust Y-pipe from the catalytic converter, and suspension position sensor; also remove intermediate shaft of power steering gear and rear transaxle mount. Place the front part of the subframe on blocks, and set up the rear part of the engine/transaxle assembly subframe on a floor jack then unscrew the four subframe bolts to allow the lowering of the unit to reveal the rear exhaust manifold. Place the assembly on a jackstand, disconnect the exhaust Y-pipe from the exhaust manifold and then loosen the bolts joining the exhaust manifold to the cylinder head. Again for the 2000 and later models, you need to also take out the exhaust crossover pipe and the right side coolant heater assembly if there is and then remove the exhaust manifolds by unbolting them from the cylinder head. During installation, the manifolds and the fasteners must be checked for cracks and damages; the surface of the manifolds has to be scraped clean of old gasket material and carbon deposits; the new gaskets should be fitted over the cylinder head studs; and the manifolds properly installed, the mounting nuts to be tightened starting from the inside out to the recommended torque. Replace and bolt in the front engine mount and bracket, the radiator, the engine cooling fans, and fill the cooling system, start the engine and inspect for exhaust leaks. The following is the process of assembling the car; bolt the exhaust Y-pipe to the rear exhaust manifold, the intermediate shaft to the steering gear, others would be the reverse order of how they were removed but replace the gaskets when joining the exhaust pipes, fill the cooling system, start the car and check exhaust manifold gasket.