Exhaust Manifold and Front Tube Leak Check
Exhaust Manifold and Front Tube Leak Check1. Position the vehicle on a hoist ready to be lifted.
2. Turn the ignition OFF.
3. Raise the vehicle on the hoist.
4. WARNING: Wait for the exhaust system to cool before touching exhaust system components. Hot exhaust components can cause severe burns.
5. Remove the cross brace shown in Figure P2.
^ Cross brace is held on with 4 bolts, 2 on each side.
6. Unbolt the front exhaust tube hanger.
^ Hanger is held on with 2 bolts.
7. Unbolt the front exhaust tube from the center exhaust tube at the flange.
^ Flange is held together with 2 studs and 2 nuts.
8. Attach an elastic strap (or other suitable support) under the rear of the front exhaust tube (see Figure P5).
NOTE:
The elastic strap should support the front exhaust tube when it is disconnected from the center exhaust tube.
CAUTION:
Make sure exhaust tube has cooled enough not to burn the elastic strap or other support.
9. Disconnect the front exhaust tube from the center exhaust tube.
NOTE:
Make sure the rear oxygen sensor harness is not stretched.
10. Let the elastic strap (or other suitable support) support the front exhaust tube.
CAUTION:
Make sure exhaust tube has cooled enough not to burn the tube elastic strap or other support.
11. Attach special tool J-50976 to the rear of the front exhaust tube as shown in Figure P7.
CAUTION:
Make sure High Temperature Gasket (J-50976-3) has been installed on the special tool before bolting to the tube.
12. Connect a shop air hose to special tool J-50976.
13. Set the valve on special tool J-50976 to the open position (see Figure P9b).
14. Attach a 19 mm socket with handle to the front crank pulley (see Figure P9a).
15. Position the engine crank shaft at the point of the highest pressure on the gauge as follows:
WARNING:
Make sure the ignition is OFF or the engine may turn on its own.
a. Watch the pressure gauge while slowly turning the engine (see Figures P9a and P9b).
^ Turn the engine clockwise (as you face the front of the engine).
b. When the pressure gauge is reading at the highest point (most PSI) stop turning the engine.
^ Highest pressure will be between 5 and 6 PSI.
16. Check for leaks as follows:
a. Turn the valve to the closed position.
b. The pressure will start to drop.
c. When pressure drops to 5 PSI, begin a 20 second count.
d. At the end of the 20 second count, read the pressure.
Go to OK/NG information below.
OK: Pressure is 2 psi or above; there is no leak in the front tube or manifold.
> If vehicle has more than 50,000 miles, go to Exhaust Manifold Replacement.
> If vehicle has less than 50,000 miles:
^ Refer to the "Exhaust Manifold Stay."
^ Reinstall the front exhaust tube.
Use a new gasket between the front tube and the center tube.
Nuts for the front exhaust tube to center tube; torque to 14 N-m (1.4 kg-m, 10 ft-lb).
Bolts for front exhaust tube hanger; torque to 14 N-m (1.4 kg-m, 10 ft-lb).
Bolts for cross brace; torque to 21-29 N-m (2.1-2.9 kg-m, 15-21 ft-lb).
NG: Pressure is below 2 psi; there is a leak in the front tube, manifold, or gasket.
A. By feel and sound, locate the leak.
NOTE:
^ If needed, eliminate any air hiss noise from the air supply hose or the tool regulator by disconnecting the air hose from special tool J-50976.
^ If needed, use soap and water to confirm leak location.
B. Replace only the leaking part (gasket, front exhaust tube, and/or exhaust manifold).
NOTE:
^ For all vehicles with more than 50,000 miles, replace the exhaust manifold even if it does not have a leak.
^ Replacement of the exhaust manifold includes removal of the exhaust manifold stay.
> For a leak at the gasket between the exhaust manifold and front tube; refer to (Front Exhaust Tube Replacement) and replace only the gasket.
> For a leak at the gasket between the exhaust manifold and engine head; refer to (Exhaust Manifold Replacement) and replace only the gasket.
> For a leak in the front tube; refer to (Front Exhaust Tube Replacement).
> For a leak in the exhaust manifold; refer to page 13 (Exhaust Manifold Replacement).