Hummer H1 Service Manual page 116

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Inspect the oil pan for cracks, sealing surface distortion, dents,
and damaged threads (Figure 2-151).
Small dents, not involving stretched metal, are not a cause for
replacement. Larger dents involving stretched or creased metal
will result in leaks.
Inspect the drainplug and pan for crossed or stripped threads
and burred flats. Discard the plug gasket. Replace the drain-
plug if damaged.
PAN SEALING SURFACES
Figure 2-151: Oil Pan Inspection Points
B
A. MAIN BEARING JOURNAL MARKINGS (BLUE, ORANGE/RED, OR WHITE)
B. ROD BEARING JOURNAL MARKINGS (YELLOW OR GREEN)
05745159
DRAIN PLUG
GASKET
A
Figure 2-152: Crankshaft Journal Size Identification
INTAKE AND EXHAUST MANIFOLDS
The manifolds can all be immersed in parts cleaning solvent.
Carbon buildup in the exhaust manifolds can be removed with
carb cleaner, wire brushing, or glass beading.
Check the manifold flange and gasket surfaces with a straight-
edge. Replace any manifold with warped, distorted surfaces.
Do not machine either type manifold in an attempt to salvage
it.
Minor scratches and nicks on gasket surfaces can be smoothed
with 80 grit emery cloth, an oil stone, or fine tooth file.
Inspect the manifolds for cracks on all surfaces. Check the ex-
haust manifolds and exhaust inlet pipes for splitting and flange
or joint separation. Although seriously damaged parts should
be replaced, minor damage on low mileage steel exhaust parts
can be repaired by welding.
Inspect manifold fittings and threads. Replace loose damaged
fittings and repair thread damage with a tap or helicoil insert.
B
A
Engine 2-79