Flushing Engine Cooler - Hummer H1 Service Manual

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2-78 Engine
OIL FILTER ADAPTER AND BYPASS VALVE
SERVICE
Oil Filter Adapter
Inspect the adapter fitting and bolt for damaged threads
(Figure 2-149). Replace either fitting if damaged.
Inspect the filter adapter for stripped or crossed threads, cracks,
and chipped sealing surfaces. Replace the adapter if damaged.
Remove and discard the old O-rings and gasket from the bolts
(Figure 2-149). Install new O-rings and seal on the bolt and lu-
bricate them with engine oil.
OIL FILTER ADAPTER
ADAPTER
FITTING
ADAPTER BOLT
OIL FILTER
BYPASS VALVE
Figure 2-149: Filter Adapter and Bypass Valves
O-RINGS
GASKET
CUP PLUG
COOLER
BYPASS
VALVE
OIL
GALLERY
PLUG
Bypass Valve
Remove the two bypass valves (Figure 2-149), and inspect
them carefully. Replace either valve if damaged, or filled with
shavings and/or debris.
NOTE: The filter bypass and cooler bypass valves can be re-
moved with a small hook tool.

FLUSHING ENGINE COOLER

Flush the engine oil cooler whenever a component failure con-
taminates the oil with metal or similar particles. The oil and fil-
ter should also be changed.
Cooler Flushing Procedure
1. Remove oil cooler lines at engine and allow oil to drain
into suitable container.
2. With one line positioned in container, introduce air
pressure (no more than 20 psi (140 kPa)) into the other
line to force oil and contaminates out of cooler.
3. When cooler is clear of oil, use pump or vacuum unit to
then either pump or draw solvent followed by fresh oil
through cooler. Continue until oil coming from cooler is
free of contaminants.
4. Reconnect cooler lines to engine adapter fittings.
5. Change engine oil and filter.
ROCKER COVER AND OIL PAN SERVICE
Clean the pan and covers in cleaning solvent. Use carb cleaner
on stubborn deposits if necessary.
Inspect rocker covers and oil pan for cracks, sealing surface
distortion, and dents. Repair minor dents. Replace either cover
if damaged (Figure 2-150).
ROCKER ARM COVER
Figure 2-150: Rocker Arm Cover
FLANGE
SEALING SURFACE
®