Air Leak Check

Fig. 18 Checking for air leaks:

1. Run engine until it reaches operating temperature, then connect tachometer.
2. Using suitable petroleum based aerosol cleaner with directional tube, spray following gasket connection points, noting any change in engine RPM, Fig. 18:
a. Lower intake manifold to cylinder head.
b. Upper intake manifold to lower intake manifold.
c. Throttle body to upper intake manifold.
d. Throttle body shaft area.
e. Idle speed controller to throttle body.
f. EGR valve gasket.
3. If idle speed changes when specific area is sprayed, replace gasket in that area.