Diesel Engine Troubleshooting

Ford 7.3L DI Low Oil Pressure

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If you have not already done so, check the oil level in the pump reservoir, which should come to within an inch of the top of the unit. If the engine has been idle for a long period, oil drains back out of the reservoir, making for hard starting.

Verify that there are no leaks at the line connections, around HEUI bodies and into the fuel system. Remove the valve covers and look for cracks in the casting, caused by mis-drilled oil galleries. Small leaks can be detected bypressurizing each gallery with an injector tester or a grease gun and a 3000-psi pressure gauge. Charge the gallery with oil at 2000 psi and wait several hours for any leaks to register on the gauge.

The next step in the search for causes of low oil pressure is to check the IPR (functionally similar to the Caterpillar IAPCV). If the 5V +/_ 0.5V reference signal is present and the output circuit is not shorted or open, replace the regulator o-rings with parts available from Ford International or aftermarket sources. The DF6TZ- 9C977-AN Dipaco repair kit services IPRs used before and after engine SN 187099. If o-rings do not solve the problem, the regulator should be tested by substitution of a known good unit and, if necessary, replaced. Torque to 35 ft/lb and do not use sealant that could clog the orifice on the threaded section.

Written by Ed

February 14th, 2011 at 7:56 am

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