Fuel Dilution Of The Oil In 3500B Engines Caterpillar

OFF-HIGHWAY TRUCKS

WHEEL LOADERS

EXCAVATORS

ENGINES

Problem:

Some 3500B Engines have experienced fuel injector failures at low operating hours. As a result of these failures, fuel may dilute the engine lubricating oil. Some symptoms of fuel dilution of the oil follow:

* Low engine oil pressure

* High crankcase pressure

* Engine miss

* Excessive black smoke in the exhaust

* Fuel in the exhaust manifold

* Low power

Injector failure with resulting valve bridge damage is the common complaint. The 3500 Engines in D11R Tractors and 992G Wheel Loaders have experienced this failure to date. The failures occurred after 250 hours or less of operation.

Solution:

The root cause of this problem is under investigation. Oil sampling is a good indicator of fuel dilution of the oil. A dilution level of 4 percent will begin to damage the engine. If the engine has experienced a dilution level of 8 percent, and a seized fuel injector is discovered, inspect the following components for abnormal wear:

* Valve bridges

* Camshafts

* Connecting rod bearings

* PTO bearings

A borescope should be used to inspect the cylinder pack that had the seized injector.

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