The catalytic converters on the Chevy S10 has undergone many changes throughout the years. The older style S10s had the converter installed downstream in the exhaust system and were clamp-connected to the exhaust pipes. The newer S10s have the converters integrated with the front Y-exhaust pipe. In any case, if you have to replace one, the direct-fit option is going to be a much wiser choice as it will save you time and money than trying to cut and weld in the cheaper universal converter choices.
Place the tools and converter in the tool tray and lift the S10 on a vehicle lift safely and securely. Put on the safety glasses inspect the catalytic converter. The inspection of the converter should have already been performed before obtaining the new replacement on the tool cart, but it would be recommended to ensure you have the right replacement part before cutting the old one down.
Locate the oxygen sensor port(s) in the catalytic converter. If its an older S10, there will be one port located on the inlet pipe of the converter. If it's a newer S10, there will be three ports located on each side of the Y-pipe inlets and one more on the rear converter of the pipe. Spray lubricant on the threads of the sensors and allow it to soak in. Unplug the oxygen sensor wire(s) using the screwdriver to help you press in on the clip lock on the plugs. Remove the oxygen sensor(s) using the oxygen sensor socket and the ratchet. Mark the sensors to identify their position if you have the three sensor portholes.
Put on the cutting glasses and gloves and light the torch. Start at the front of the converter. If it's a three-point flange, cut out the nut and bolts. If it's the Y-pipe converter, heat up the nuts on the studs (one at a time) with the torch and have your pneumatic gun, long extension, swivel and socket ready to extract the nut once properly heated. This will avoid snapping a manifold stud. Remove all three nuts per side (six in all) in this fashion.
Cut the three bolts and nuts out of the rear flange (two bolts on the Y-pipe). Be aware that certain year S10s may have welded studs in the rear flange. You can try to reuse these or you could cut them out and replace them with nuts and bolts. They'll be stubborn to cut out, but unless they're really clean, it would make an easier fix to replace them. Shut off the torch and switch back to the safety glasses after the converter connections are disconnected.
Carefully remove the converter. Disengage any rubber hangers from the welded hangers on the converter. Be careful not to burn yourself as the shell of the converter will be hot and can still burn through safety gloves.
Install the new converter and attach it to the front of the S10 first with the replacement gaskets. It will take some wrangling if it's the Y-pipe converter to fit it up. Place the welded hanger in the converter through the rubber hanger to help hold it in place. Place the nuts on the studs to hold the converter. For the three-bolt flange type converter, simply insert the gasket in between the flanges and place the bolts and flat washers on one side of the flange and the lock washers and nuts on the other side.
Connect the rear converter flange with hardware and the gasket in the same manner -- bolts and flat washers on one side of the flange and lock washers and nuts on the other side. Tighten the flange connections using the gun, with swivel, socket, and any necessary length extension on the nut while holding the bolt head with a box end wrench. Tighten each nut and bolt slightly and alternate between each one to draw them in evenly and then tighten them snug at the end.
Place a light amount of anti-seize lubricant on the threads of the oxygen sensor(s) and thread them into the portholes by hand. Tighten the sensor(s) snugly with the ratchet and oxygen sensor socket, but be careful not to overtighten and strip the threads of the sensor(s). Plug the sensor(s) wire back into the plug connection.
Remove the tool tray and debris from under the S10, lower the truck on the lift and start it up before swinging the lift arms free. Make sure there are no exhaust leaks coming from any of the flange connections or oxygen sensor port(s).
