GMC T Series 1994 Repair Manual page 529

3. Main bearing bores and main bearing caps.
• All main bearing bores should be round and
uniform in ID at all bearing supports.
• The area where the main bearing inserts con­
tact the main bearing bore must be free of burrs
and scratches.
4. Head gasket surface for scratches, burrs and dam­
age.
Measure
Fire deck warpage. Use a straightedge and feeler
gage. If the block is warped more than 0.15 mm
(0.006 inch) longitudinally or 0.08 mm (0.003 inch)
transversely, it should be replaced. Do not attempt
to resurface the fire deck or cylinder head.
+4-
Install or Connect
1. Oil cooler bypass valve, using a socket to drive the
bypass valve into the bore until seat on shoulder in
bore.
2. Cup plug for oil cooler bypass valve. (This plug has
an orifice hole that prevents an air lock from occur­
ring and blocking oil flow).
3. Oil filter bypass valve.
• Use a socket to to drive valve into bore until it
seats against shoulder in bore.
4. Expansion plugs and oil galley plugs.
5. Block heater.
6. Block drain bolt (if used).
5. PLUG, OIL PRESSURE SENSOR
6. BLOCK, ENGINE
11. PLUG, OIL GALLEY
14. PLUG, MAIN GALLEY HOLE
17. PLUG, COOLANT JACKET
18. PLUG, COOLANT DRAIN
19. PLUG, TURBO OIL FEED
20. HEATER, ENGINE BLOCK
Tighten
• Bolt to 25 N-m (18 lbs. ft.).
CYLINDER BORES
i? Inspect
Cylinder bores for scoring and other damage.
Measure
• Cylinder out of round and taper. Refer to " Cylinder
Bore Reconditioning G uidelines" and (figures 33
and 34)
CYLINDER BORE RECONDITIONING GUIDELINES
• If any of the cylinder bores are scored or worn to
the extent that they will not clean up when bored
and honed to the size to accommodate the largest
service piston available, the cylinder block can not
be reused.
• If one or more cylinder bores are scored or worn
only to the extent that they will clean up when
bored to the size to accommodate the largest ser­
vice piston, it will be necessary to rebore and hone
such bores to fit new pistons and rings.
• Also if bore out-of-roundness and taper measure­
ments exceed 0.020 mm (0.0008 inches), it will
again be necessary to rebore and hone such bores
to fit new pistons and rings. Refer to figures 33 and
34.
V2987