Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1985ECONOLINE E350, VAN DISPLAY, 5.8 GREPAIR AND DIAGNOSISTRANSMISSIONAUTOMATIC TRANSDIAGNOSIS & OVERHAUL - C6TESTINGCONTROL PRESSURE TESTVACUUM PUMP METHOD
1985 Ford Econoline E350, Van Display, 5.8 G
Vacuum Pump Method
1985 Ford Econoline E350, Van Display, 5.8 GSECTION Vacuum Pump Method
- Attach tachometer to engine and a 0-400 psi gauge to pressure take-off point at transmission. Disconnect and plug manifold vacuum line at diaphragm unit.
- Connect vacuum source (vacuum pump in distributor tester). Apply both parking and service brakes. Start engine and vacuum pump, setting vacuum to 15 in. Hg. Read and record control pressure in all shift selector positions.
- Increase engine to 1000 RPM; and reduce vacuum to 10 in. Hg. Read and record control pressure in "D", "2" and "1" shift selector positions.
- With engine still at 1000 RPM, reduce vacuum to 1 in. Hg. Read and record control pressure in "D", "2", "1" and "R". Compare control pressures obtained in tests with pressures given in appropriate CONTROL PRESSURE SPECIFICATIONS table.NOTE: Governor can be checked at same time control pressure test is performed.
- With vehicle raised, place selector lever in "2", no load on engine and apply 10 in. Hg. Increase speed slowly while watching speedometer, check speed at which control pressure cutback occurs. It should occur between 10-20 MPH.
- Decrease vacuum to 0.2 in. Hg. and repeat test. Control pressure cutback should occur between 30-50 MPH. If cutback does not occur within specifications, check shift speeds to make sure that it is the governor and not a stuck cutback valve.CAUTION: DO NOT exceed 60 MPH speedometer speed during test. If control pressures are not within specifications, proceed to CONTROL PRESSURE TEST RESULTS to determine problems.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.