Two types of exhaust manifolds are used. One type has an outlet to accommodate a square exhaust outlet
flange (Fig. 1) and the other has a circular outlet which is connected to the exhaust pipe with a Marmon-type
clamp (Fig. 2). Current manifolds, flanges (square), and flange gaskets have SAE standard dimensions.
On engines equipped with a mechanical automatic shutdown system, the exhaust manifold is provided with two
5/16-18 tapped bolt holes and a 7/8 inch drilled hole to permit installation of the temperature shutdown valve
adaptor and plug assembly.
Remove Exhaust Manifold
Disconnect the exhaust pipe or muffler from the exhaust manifold flange.
If the engine is equipped with a mechanical automatic shutdown system, remove the two bolts and
lockwashers and withdraw the shutdown valve adaptor and plug assembly from the exhaust manifold.
Loosen, but do not remove, one of the center exhaust manifold nuts. Remove the other nuts and
Support the manifold and remove the center nut and washer.
Remove the manifold and gasket from the cylinder head.
Remove any loose scale and carbon that may have accumulated on the internal walls of the exhaust manifold.
Clean the manifold and check for cracks, especially in the holding lug areas.
Clean all traces of gasket material from the cylinder head.
Examine the exhaust manifold studs. Replace damaged studs. Apply sealant
Figure 1 . Typical Air-Cooled Exhaust Manifold (Square Flange) Mounting