300SD (140.134) L6-3.5L DSL Turbo (603.971) (1993)
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Vacuum Pump: Testing and Inspection
Piston Type
1.
Connect suitable vacuum gauge to vacuum line between brake booster and check valve.
2.
Start engine and run at 750 RPM and note length of time required to obtain 14.8 inches Hg vacuum.
3.
On models equipped with 9 inch double diaphragm brake booster, elapsed time should measure 13-14 seconds with brake unit and all vacuum
accessories vented and 9-11 seconds with brake unit only vented. On models equipped with 10 inch single diaphragm brake booster, elapsed time
should measure 12-13 seconds with brake unit and all vacuum accessories vented and 7-9 seconds with brake unit only vented.
4.
On all models, if elapsed time is not within specifications or if vacuum drops more than 5.9 inches Hg in 30 seconds, check vacuum system for
leaks. If no leaks are found, repair or replace vacuum pump as necessary.
