RAM 2500 Truck 2WD L6-359 5.9L DSL Turbo VIN D FI (1997)
EGR Valve: Testing and Inspection
Fig 6 Vacuum Pump At EGR Valve
Use the following test procedure to determine if exhaust gas is flowing through the EGR valve. It can also be used to determine if the EGR tube is
plugged, or the system passages in the intake or exhaust manifolds are plugged.
This is not to be used as a complete test of the EGR system.
1. To verify EGR valve operation, it must be removed from intake manifold. Refer to EGR Valve Removal/Installation procedures.
2. Examine the head of poppet valve at base opening on bottom of EGR valve. Look for heavy carbon build-up. A coating of carbon is normal with
engine operation. Shine a bright light through valve opening and examine edge (seat) of poppet valve. No light should be evident at valve edge. If
either condition exists, replace EGR valve. Do not attempt to clean the poppet valve within the EGR valve assembly
3. The EGR valve is equipped with a fitting located on the EGR valve vacuum motor (Fig. 6).
4. Connect a hand-held vacuum pump equipped with a vacuum gauge to this fitting (Fig. 6).
5. Slowly apply 10 inches HG of vacuum to the fitting on the EGR valve motor. The poppet valve (Fig. 6) should start to open at approximately 10
inches of vacuum. Vacuum should hold steady at 10 inches. If not, replace the EGR valve. If vacuum holds steady at 10 inches, and poppet valve
has started to open, proceed to next step.
6. Continue to apply vacuum until gauge reading is at 20 inches. The poppet valve should be fully open at approximately 20 inches of vacuum.
Vacuum should also hold steady at 20 inches. If not, replace the EGR valve.
7. If the EGR valve tested OK, the EGR tube may be plugged with carbon, or the passages in the intake and exhaust manifolds may be plugged with
carbon.
8. While the EGR valve is removed, check passages in EGR tube. Remove the EGR tube between the intake and exhaust manifolds. Check and clean
the EGR tube and its related openings on the manifolds. Refer to EGR Tube Removal/Installation.
9. While the EGR valve is removed, check for carbon build-up at intake manifold openings. Clean carbon deposits as necessary.
Do not attempt to clean the poppet valve within the EGR valve assembly. If the valve shows evidence of heavy carbon build-up near the base or around
poppet valve, replace it.
