TROUBLESHOOTING
Page 75
5. Apply air pressure (240 kPa [35 psi]) to the
EGR cooler. Maintain the pressure for
15 minutes. If the EGR cooler is leaking
internally, there will be a steady stream of
bubbles coming from the gas inlet or outlet
openings. If a steady stream of bubbles
appears, replace the EGR cooler.
If the cooler is being tested without being
immersed in water, look inside the gas inlet port.
If bubbles are seen, the cooler is leaking
internally and must be replaced.
A stream of bubbles seen coming from around
the plugs in either of the coolant ports indicates
that the O-rings may be damaged. If this is the
case, remove the plugs, inspect the O-rings and
replace as required.
6. Lift the EGR cooler out of the container and
remove the pressure testing equipment.
7. Dump the water from inside the EGR cooler
and then use compressed air to remove any
remaining water from the cooler core and
outer cover.
Engine Compression, Test
(on Vehicle)
Verify suspected leaks in the cylinder head or
block by pressure testing before replacing these.
Do not use Magnaflux
®
inspections alone as
replacement criteria.
Before proceeding with the tests, look for coolant
stains around the sealing plugs on the cylinder
head. Check that the plugs are installed properly
and in good condition.
1. Remove the cylinder head (valve) cover.
On engines fitted with PowerLeash™, secure the
pistons in the rocker arms with rubber bands or
tie straps so the pistons do not drop out when the
rocker assembly is lifted. Pistons and rockers are
matched together. Failure to heed this caution
may result in severe component damage.
61
Figure 61 — Tie Strap Holding Engine Brake Piston
(MP7 Shown)
2. Remove the PowerLeash™ (engine brake)
control valve if so equipped.
It is very important to loosen the rocker arm shaft
assembly uniformly across the complete shaft.
Loosening the rocker shaft assembly unevenly
can cause damage.
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