Cleaning, Inspection, And Repair; Block - GMC 1989 Light Duty Truck Repair Manual

6A1-14 2.5 LITER L4 ENGINE
103
T im in g M arks
C ra n k s h a ft G ear
T h ru s t Plate B o lts
C a m s h a ft G ear
T h ru s t Plate
C a m sh a ft
Figure 21 — Camshaft and Timing Gears

CLEANING, INSPECTION, AND REPAIR

A solvent tank, large enough to hold the larger engine
parts, will be needed along with various bristle brushes
and a gasket scraper. A source of compressed air will be
helpful in the cleaning operations.
Precision measuring tools will be required for the in­
spection procedure. These include: micrometers, cylinder
bore gage, feeler gages, dial indicator set, etc. The in­
spection work, performed with the proper method and
tools, is most important. The rebuilt engine cannot be ex­
pected to perform properly if parts worn beyond accepta­
ble limits are reused.

BLOCK

Clean (Figure 5)
1. Block (119) in solvent.
2. Block gasket surfaces.
3. Cylinder bores.
4. Oil galleries and passages.
5. Scale deposits from the coolant passages.
F-05719
Inspect
1. All expansion plugs for looseness or leakage.
2. Valve lifter bores for deep scratches and varnish
deposits.
3. Block for cracks, especially in the following areas:
• Cylinder walls.
• Coolant jackets.
• Main bearing webs.
• Engine mount bosses.
4. Main bearing bores and main bearing caps (124 and
126).
• All main bearing bores should be round and
• The area where the main bearing inserts (86
M easure (Figure 22)
Head gasket surface distortion. Use a straight edge
and a feeler gage to check for flatness of the milled
surface at the top of the cylinder block. The surface
have a uniform inside diameter at all of the
bearing supports.
and 72) contact the main bearing bore should
be smooth.