GMC 4000 Series Service Manual page 268

again. The upper mark on dipstick is "FULL," the
lower "ADD" or "ADD OIL." Keep level as close
as possible to "FULL" mark without over-filling.
Do not operate with level below "ADD" or "ADD
OIL" mark. Dipstick is at the right side of engines.
When replenishing oil supply in crankcase, add oil
of same brand and quality as is used when changing
oil.
Refer to LUBRICATION (SEC. 0) earlier in
this manual for recommendations pertaining to oil
change intervals and oil filter replacement intervals.
CHECKING DRIVE BELTS
1. Inspect drive belts for excessive wear and
damage. If no defects are found, check belts for
proper tension.
2. When installing new drive belts or adjust­
ing old belts, use tension gauge to provide correct
tension.
CAUTION: Adjusting drive belts too
tightly will impose too great a load on
bearings in the driven units. Slipping will
occur if drive belts are not adjusted tight
enough. Belt life will be shortened if belts
are not properly tightened.
ENGINE OIL FILTERS
Engine oil filters are either standard or op­
tional equipment, and are either of two types. F il­
ters shown in figures 1 and 3 are throw-away type.
Replaceable element type oil filters (figs. 2 and 5)
are used instead of throw-away filters on some
engines.
REPLACING OIL FILTER
(THROW-AWAY TYPE)
1. Use filter wrench to screw the oil filter off
stud on mounting bracket. Discard the filter a s­
sembly.
2. Thoroughly clean gasket area on filter
bracket.
3. Apply engine oil on filter gasket (gasket is
bonded to filter assembly), then thread filter onto
stud until gasket contacts bracket. Tighten filter
V z turn after gasket has contacted mating surface
on filter bracket.
4. Start engine and inspect for leaks at oil
filter. Check crankcase oil level at dipstick. Add
oil if required to raise level to "FULL" mark.
REPLACING OIL FILTER ELEMENT
(REPLACEABLE ELEMENT TYPE FILTER)
1. If filter housing has drain plug, remove
plug and allow oil to drain from housing. Use
wrench to loosen filter housing bolt, then remove
bolt, housing, and filter element as an assembly.
Remove housing gasket.
G M C S E R V I C E M A N U A L
1 Filter Shell
2 Filter Element
3 Shell Gasket
4 Housing and Adapter
5 Housing
element. Clean housing thoroughly. Also clean fil­
ter bracket.
with new oil, place housing gasket at filter bracket,
and install housing and element assembly. Tighten
housing retaining bolt.
necessary, add oil to raise oil level to "FULL"
mark on dipstick. Refer to figure 4.
OPTIONAL OIL FILTER AND ADAPTER
2-quart filter, an adapter is bolted to block with
special socket-head bolts.
gasket (9 and 10) between adapter and cylinder
block. Tighten adapter bolts (11) to 35 foot-pounds.
When installing housing (5), tighten bolts (4) to 30
foot-pounds torque.
FILTER BY-PASS VALVE
REPLACEMENT (Some Engines)
type filter is mounted has a by-pass valve assem ­
bly as shown in figure 3.
GASOLINE ENGINES
6 Housing Gasket
7 Adapter
8 Engine
9 Adapter-to-Block Seal
Bolt di Lock Washer
10 Adapter Gasket
11 Adapter-to-Block Bolt
Figure 5 — Oil Filter and Bracket Components
(Opt. 2 qt. Type on 2 9 2 Engine)
2. Remove element from housing and discard
3. Install new element in housing, fill housing
4. Start engine and inspect for oil leaks. If
Key numbers in text refer to figure 5.
When In-line engine is equipped with optional
When replacing adapter (7), use new seal and
The oil filter bracket on which the throw-away
Sec. 6A
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