Mack E7 Service Manual page 286

5-101.bk Page 14 Friday, March 17, 2006 11:05 AM
CYLINDER BLOCK/CYLINDER HEAD
COOLANT PASSAGES LEAK CHECK —
IN CHASSIS
Refer to Figure 9-4.
1. Drain coolant from the engine.
2. Remove the engine oil pan and valve lifter
covers.
3. Remove the water pump assembly and use
a suitable plate and gasket to seal opening.
4. Remove the upper and lower hoses from the
thermostat housing. Remove the thermostat
housing and thermostat.
5. Secure a suitable plate and gasket over the
thermostat housing opening.
6. Install an air fitting into one of the pipe plug
holes in the coolant manifold.
7. Reinforce the hose connecting the coolant
manifold sections by installing a hose clamp
around the center of the hose to prevent the
hose from rupturing during testing.
8. Remove one of the large pipe plugs from the
water manifold and add hot water to fill the
cooling system. Increase cylinder block
temperature to 150°F (66°C). Loosen one of
the pipe plugs near the top of the cylinder
block to bleed air from the water jacket while
filling. Also open the block drain to allow
water to flow out. This will help warm the
cylinder block.
9. After cylinder block is sufficiently heated,
close block drain and apply approximately
50 psi (345 kPa) air pressure to the air
connection.
Page 9-14
200 TROUBLESHOOTING
Do not exceed 50 psi (345 kPa) air pressure.
Damage to seals or cup plugs may result.
Water leaking from the No. 2 or No. 5 cam
bushings or from the No. 2 or No. 5 main
bearings can indicate a breakthrough between
the rocker arm feed passage and the water
jacket.
Refer to the repair procedures in this manual to
correct leaks.
10. Check for coolant leaks at the bottom of
each cylinder bore.
Coolant leaking between the cylinder
sleeve outside diameter and cylinder
block indicates a leaking cylinder sleeve
seat.
Coolant leaking down the inside diameter
of the cylinder sleeve indicates a leaking
head gasket.