JBA 1646SJT - Manual (Page 3)

Converter assembly by sliding it rearward from the engine. Save all fasteners for re-installation
6. Unplug the O2 Sensor wire(s). Access to the O2 sensor plug(s) may be obscured by the transmission. Loosen-
ing the Y Pipe from the factory manifolds should make access easier. Remove the O2 sensors using either a box
wrench or a special O2 sensor socket which can be purchased at most auto parts stores. Take care not to drop the
O2 sensors. Finish removing the bolts and maneuver the factory Y-Pipe out from under the vehicle.
7. If equipped remove the EGR tube from the EGR valve and the exhaust manifold.
8. Unbolt the dipstick tube bracket from the engine. Carefully slide the dip stick tube upward to remove. Unbolt
the Driver’s side exhaust manifold and remove from the top side. Remove the gaskets and any gasket material or
any carbon deposits that remain on the head surface. The use of a gasket removal agent will ease the removal of
any gasket material. Use care not to get debris into ports or spark plug holes.
NOTE: ‘90-‘94 4.0 Explorers and ‘90 to ‘92 Rangers use a single O2 sensor and no EGR. ‘93 to ‘94 Rangers
utilize two O2 sensors and an EGR fitting. The 1633-1 header has fittings to accommodate these differences.
The supplied plugs should be used to close any unused fittings.
9. Apply anti-seize to the header bolts if installing on aluminum heads. Bolt the Driver’s side header to the
engine using the supplied gaskets, bolts, and lock washers. Torque to 30 lbs./in on iron heads, 23 lbs./in on
aluminum heads.
10. Models with EGR fittings only. Remove the EGR adapter fitting which adapts the EGR tube to the fitting on
the factory manifold. This adapter must be reused. Thread the adapter into the fitting on the header and recon-
nect the EGR tube. (Note: 3.0L Models may or may not have this adapter)
11. Clean all grease or oil from the outside of the dip stick tube. Apply a small amount of silicone sealant to the
outside of the dip stick tube where it slip-fits into the engine. Reinstall the dip stick tube. Make sure that the
dipstick tube is not too close to the header tubes.
12. If equipped, remove the heat riser tube from the passenger side manifold. Unbolt the passenger side mani-
fold and remove from the underside of the vehicle. Remove the gaskets and any gasket material or any carbon
deposits that remain on the head surface. The use of a gasket removal agent will ease the removal of any gasket
material. Use care not to get debris into ports or spark plug holes.
13. Maneuver the passenger side header into place from under the vehicle. Apply anti-seize to the header bolts if
installing on aluminum heads. Bolt the header to the engine using the supplied gaskets, bolts, and lock washers.
Torque to 30 lbs./in on iron heads, 23 lbs./in on alum. Re-attach the heat riser tube.
14. Install the O2 sensor(s) in the new Y-pipe. Apply a thin coating of High Temperature, Sensor Safe, Silicone
Sealant to the collector domes of the Headers. Apply a small amount of sealant to the Driver’s side half of the
Y-Pipe where it slip fits into the Passenger side half of the Y-Pipe and slide the two halves together. Loosely bolt
the Y-Pipe to the headers. Plug the O2 sensor wire(s) in. Loosely bolt the Y-Pipe clamp in place .
15. Make sure that the mating surface of the Catalytic Converter flange is clean. The gasket may be reused if
undamaged. Apply High Temperature, Sensor Safe, Silicone Sealant to both surfaces of the gasket. Slide the
catalytic converter assembly into its mount and loosely bolt the Y-pipe to the catalytic converter. Re-attach the
muffler assembly. After checking to insure that all components are aligned properly, tighten all bolts to factory
specs.
16. Reinstall the spark plug wires and looms taking care not to let any wires come into contact with the headers.
Reinstall the battery cable. Make sure that the battery cable is routed away from the headers.
17. Check that all bolts are tight. Make sure that all wiring, fuel lines, transmissions lines, brake lines etc are
clear of the headers and the exhaust and relocate as necessary.
18. Start the engine and let it warm up. Check for leaks. Shut engine off and let it cool down. Check to make
sure all fasteners are tight.
19. Periodically check & retighten the header bolts.