Remove and Install EXHAUST MANIFOLD (Air-Cooled) Detroit Diesel 92 Series Engine [Archive]

NewellCrazy

02-07-2013, 04:20 PM

EXHAUST SYSTEM

Fan and radiator cooled engines are equipped with an air-cooled exhaust manifold. A water-cooled exhaust manifold is provided for engines incorporating a heat exchanger or keel cooling system.

The outlet flange may be located at the end or at the mid-section of the exhaust manifold, depending upon the installation requirements. A flexible exhaust connection or a muffier may be attached to the outlet flange.

The exhaust manifold is attached to studs located between the exhaust ports and the outer side of the two end ports in the cylinder head. Special washers and nuts secure the manifold to the cylinder head.

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 EXHAUST MANIFOLD (Air-Cooled)

The cast air-cooled manifold (Fig. 1) has a uniform circular cross-section and tapers upward from each end toward the center where a flange is provided for the attachment of the exhaust piping or muffler.

A new exhaust manifold hold-down crab is now being used. The new hold-down crab is made of a hardened steel and is heavier than the former hold-down crab. This will minimize wear and gouging of the manifold, crab and cylinder head mating surfaces, which results in a loss in the torque on the hold-down crab nut. The former and the new hold-down crab are interchangeable on an engine however only the new crab will be serviced.

Also a new special washer is now used at the center portions of the exhaust manifolds. This new washer will more accurately control the seating area for the 7/16" nut or bolt. Only the new speical washer will be serviced.

Remove Exhaust Manifold

Usually, the exhaust manifold will be removed with the cylinder head. However, when the exhaust manifold gaskets only need to be replaced, the manifold may be removed in the following manner without removing the cylinder head:

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1.
Loosen
the flange seal connecting
the exhaust

manifold
at the outlet tube.

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2. Disconnect the exhaust pipe or muffier from the exhaust manifold flange.

3. Loosen and remove the nuts and bevel washers which secure the exhaust manifold to the cylinder head. It is suggested that, as a safeguard, one nut and washer be loosened and left on one of the center studs until all other nuts and washers have been removed.

4. Support the manifold and remove the nut and washer from the center stud.

5. Lift the manifold away from cylinder head.

6. Remove the manifold gaskets.

Inspection

Remove the loose scale and carbon that may have accumulated on the internal walls of the exhaust manifold. It is especially important to clean the manifold used on a turbocharged unit to eliminate the possibilty of loose scale entering and damaging the turbocharger.
Examine the exhaust manifold studs for damage. If necessary, replace the studs. New studs are driven in to
25-40 Ib-ft (34--54 Nem) torque.

Install Exhaust Manifold

With all traces of the old gaskets removed from the cylinder head and bolting flanges of the exhaust manifold, install it as follows:

1. Make sure the internal walls of the manifold are clean to eliminate possible damage to the turbocharger, if used.
2. Place new gaskets over the studs and up against the cylinder head. Metal-clad gaskets may look reusable, but once they've been used and taken a "set" they cannot be reused.
NOTICE: When installing the metal clad exhaust manifold gasket(s) be sure the crimped side of the gasket (Fig. 2) faces the cylinder head. \
3. Position the exhaust manifold over the studs and up against the gasket.
NOTICE: Be sure the locating pads on the exhaust manifold rests on the cylinder block locating pads.

(Air-Cooled) DETROIT DIESEL 92

4. Install the bevel washers and nuts on the studs and draw the exhaust manifold up against the gasket. Set the bevel washers in position so that outer diameter will rest on the manifold and the crown at the center is next to the nut. Tighten the exhaust manifold stud nuts from the center of the exhaust manifold outward, alternating toward either end. Torque the nuts to
30--35lb-ft (41-47 Nem).

5. Connect the exhaust pipe or [I]muffler to the exhaust manifold flange.

6. Tighten the flange seal connecting the exhaust manifold to the outlet tube.
NOTICE: Do not allow exhaust piping to impose excessive loads on the turbocharger.

7. Inspect the exhaust outlet piping for dents, holes and potential sources of water infiltration such as loose clamps or deteriorated seals. Repair or replace, if necessary.

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