SUPPORT-ENGINE REAR 7E0502 - Caterpillar

D346, D348, D349 EnginesReference: This article is reprinted from Service Magazine, August 31, 1978.Description of Change: A system is available to test for fuel leakage inside the camshaft housings. Fuel leakage can be at different points in the fuel system inside the camshaft housings. The result of this leakage is a mixture of fuel with lubrication oil which can cause an engine failure. This system uses a new precombustion chamber that has a drain port with a connection to the areas around the fuel nozzle and the end of the fuel line. The drain ports on the precombustion chambers are connected by tubes to the fittings in the camshaft bearing webs in the camshaft housing. Each bearing web has fittings for drain lines from two precombustion chambers. The fittings are connected to drilled passages in the webs that permit any fuel leakage to be drained to the outside of the cam housing.
External (outer) drain lines can be connected to each drain port to keep any fuel leakage away from the hot exhaust manifolds during engine test. If there is a leak, the location of the leak can be easily found and a repair made.
The engine test can then be started again to see if the repair has stopped the leak. After the test, the external drain lines can be removed and plugs installed in the drain ports on the camshaft housing. Pipe plugs are installed in the drain passages at the outside face