Air Injection System

BELT TENSION, ADJUST
Air pump belt tension should be checked with a belt tension gauge on the longest accessible span of the belt between two pulleys. When adjusting serpentine belt tension, adjust to 180 to 200 pounds for a new belt and 140 to 160 pounds for a used belt. When adjusting V-type belt tension, refer to the following specifications:
1. On 4 cylinder engines, adjust both new and used belts to 40---60 lbs.
2. On 6-258 engines less power steering, adjust new belt to 125---155 lbs., or used belt to 90---115 lbs.
3. On 6-258 engines with power steering, adjust new belt to 65---75 lbs., or used belt to 60---70 lbs.

AIR FILTER, REPLACE
Pleated Paper Type
This filter is located on the air pump and should be replaced every 12,000 miles or sooner under more adverse conditions.

Fig. 5 Removing centrifugal type pump air filter:

Centrifugal Filter Fan Type
This filter should be replaced only if damaged. To remove, first pry off the outer disc, Fig. 5, and then the remaining portion. Install replacement filter by drawing it into place using the pulley and bolts as tools. Alternately tighten the bolts making sure that outer edge of fan slips into housing. A slight amount of interference with housing bore is normal. After a new fan is installed, it may squeal upon initial operation until its outer diameter lip has worn in. This may take up to 30 miles of operation. Do not attempt to install fan by hammering or pressing it on as damage to pump may result.

Fig. 6 Removing pressure relief valve with slide hammer and tool:

Fig. 7 Installing pressure relief valve:

RELIEF VALVE, REPLACE
The relief valve may be removed by using a puller and a bridge over the valve, Fig. 6. If the new relief valve has a pressure plug, remove it before installing valve. To install valve, insert it into housing, then place a block of wood over and tap lightly with a hammer until valve is seated, Fig. 7. After valve has been installed, the pressure plug must be installed into valve by pressing against its center.




DIVERTER VALVE, REPLACE
This valve is not serviceable and must be replaced if defective. The valve is suspended by the hoses between the air pump and air injection manifolds. To remove valve, disconnect hoses and vacuum sensing line. Reverse this procedure to install. Make sure all connections are tight and not leaking.




AIR PUMP, REPLACE
4-151 Engine
1. Remove drive belt.
2. If equipped with air conditioning, remove A/C compressor-to-mounting bracket attaching bolts and set compressor aside.
3. Remove air pump drive pulley bolts and pulley.
4. Remove fuel vapor canister and mounting bracket.
5. Disconnect output hose from rear of pump.
6. Remove air pump to bracket bolt and remove air pump.
7. Reverse procedure to install. Adjust belt tension to specifications.






AIR MANIFOLDS, REPLACE
1. Disconnect air delivery hose at check valve.
2. Remove injection screws from each cylinder exhaust port. Some resistance to removal may be encountered due to carbon build-up on the screws.
3. Remove air injection manifold.
4. Reverse procedure to install.