Excessive Oil Leakage From Hydraulically Actuated Electronic Unit Injectors (Heui) Caterpillar

Excessive Oil Leakage From Hydraulically Actuated Electronic Unit Injectors (Heui)

Usage:

ENGINES

COMPACTORS

MOTOR GRADERS

OFF-HIGHWAY TRUCKS

TRACK-TYPE TRACTORS

WHEEL LOADERS

WHEEL TRACTORS

WHEEL-TRACTOR SCRAPERS

PAVING PRODUCTS

3408E (7PR),
3412E (4CR) INDUSTRIAL ENGINES;
836 (7FR) COMPACTORS;
24H (7KK) MOTOR GRADERS;
669D (5TR),
771D (6JR),
773D (7ER),
775D (6KR) OFF-HIGHWAY TRUCKS;
D9R (7TL, 8BL),
D10R (3KR) TRACK-TYPE TRACTORS;
988F (2ZR),
990 (4FR),
WHEEL LOADERS;
834B (7BR) WHEEL TRACTORS;
631E (1AB),
633E (2PS),
637E (1FB),
651E (4YR),
657E (5YR, 6TR, 7KR),
WHEEL-TRACTOR SCRAPERS;
PM565 (3TK) COLD PLANERS

THIS TIB REPLACES THE JULY 2, 1997 ENGINE TIB, COMPONENT CODE 1290. EXCESSIVE OIL LEAKAGE FROM HYDRAULICALLY ACTUATED ELECTRONIC UNIT INJECTORS (HEUI). DESTROY THE JULY 2, 1997 TIB. IT WILL NOT APPEAR IN THE QUARTERLY INDEX.

Problem:

Some of the 3408E (99C) and 3412E (80M) Engines in these machines and some 3408E (7PR) and 3412E (4CR) Industrial Engines may experience hard starting or low power due to oil leaking past the poppet valve in the injector. The oil leakage is caused by the operating conditions at either low or high idle. Excessive oil leakage can reduce actuation pressure to the fuel injector. This may prevent fuel injection.

Solution:

First, be sure to go through the normal trouble shooting procedures ("Engine Cranks, But Will Not Start" and "Consistent Low Power or Poor Response To Throttle") for the machine you are troubleshooting. If the problem is not located, and the symptoms (hard starting and/or low power) continue, remove the engine valve covers. Electrically disable the injectors. Crank the engine and watch the injector oil spill ports (see Illustration) for oil leakage. A small amount of oil leakage is acceptable, but a continuous stream of oil may mean poppet valve leakage. Excessive poppet valve leakage may prevent fuel injection.

NOTE: Injection actuation oil pressure will be less than 5 MPa (725 psi) during cranking because of excessive injector oil leakage. Do NOT change the oil pump.

Injectors that leak a continuous stream of oil from the oil spill ports should be replaced. This does NOT justify wholesale replacement of injectors. Replace ONLY the injectors that leak a continuous stream of oil from the oil spill ports.

(TOP VIEW OF INSTALLED INJECTOR)

The black arrow points to the oil drain port. On some engines, the oil drain port is relocated underneath. This will direct the oil flow downward. Excess oil leakage will still be visible on the cylinder head.