(483 kPa). After 10 to 20 minutes inspect the oil puddles to see if any have become smaller or run off
completely. The undiluted oil will hang the same as when the oil was poured on. Repair and retest.
With the engine at rest as in Method 2, all injectors will leak to some extent when pressurized.
The leakage occurs because there is no place else for the pressurized fuel to go. When the low-
and high- pressure cavities in the injector are subjected to the high-test pressure, fuel is forced
past the plunger into the rack and gear cavity. Result: Droplets of fuel form at the rack and drip
off. Slightly worn plungers may leak more under these conditions. This leakage will not occur
while the engine is running because of the dynamic and pressure conditions that exists. If
injectors are suspected of leaking and contributing to dilution of the lube oil, they should not be
tested by pressurizing the fuel system as in Method 2. Injectors should be removed from the
engine and tested for pressure-holding capability (see Troubleshooting).
Points to Remember
Lube oil puddle inspection is the key to pressure testing the fuel system for internal leaks. This test can be per-
formed any time the rocker covers are removed, after the fuel pipes and connectors have been splashed with
oil and there is normal fuel pressure in the system. The weak or missing puddles show where the leaks are.
All leakage or spillage of fuel during leak detection testing further dilutes the lube oil, so the final step in
maintenance of this type should include lube oil and lube oil filter changes.