The EGR system recirculates part of the exhaust gases into the combustion chambers. This dilutes the air/fuel mixture, reducing formation of oxides of nitrogen in the exhaust gases by lowering the peak combustion temperatures.The parts of a typical EGR system are:
- Check all vacuum hoses for cracks, breakage and correct installation.
- Check EGR valve operation by applying vacuum to the EGR valve vacuum nipple with the engine idling. The idle should become rough.
- Check the passages in the cylinder head and intake manifold for clogging. Clean as necessary.
- Cold start the engine. The EGR port nipple should be open. When the coolant is warmed to over 131°F (55°C), the port should be closed.
REMOVAL & INSTALLATION
- Remove the vacuum hose.
- Disconnect the exhaust line from the EGR valve.
- Remove the EGR valve.
- Install the EGR valve. Be sure to tighten the nut on the EGR line to 22-25 ft. lbs.
The thermo valve is located on the left side of the intake manifold. It is threaded into the manifold and can be removed with an openend wrench.
- Disconnect the vacuum lines.
- Using an open-end wrench, carefully turn the thermo valve out of the intake manifold.
- Apply a good sealer to the valve threads before installation.
- Connect the vacuum lines. The A nipple should be connected to the vacuum hose from the carburetor and the B nipple to the EGR valve.