Detroit Diesel — Control Valve Adjustment (on Bench)
Adjustments · Blower bypass valve control valve
From a Detroit Diesel service manual — check it applies to your exact model before use.
Before you start
- Proper adjustment of the control valve is critical to engine operation.
Procedure
- Attach one pressure gage to the discharge port of the control valve with a tee; plug the open end of the tee so there is no airflow beyond the gage.
- Connect the second pressure gage between the regulator and a tee fitting. Connect a hose from the tee to the control port; connect another hose from the tee to the inlet port.
- Connect shop air pressure to the regulator valve. The control hose should be in place when the valve is adjusted.
- Loosen and back out the adjusting screw on the three-way valve. Adjust the air pressure regulator to obtain a supply side pressure of 10 psi (69 kPa).
- Adjust the three-way valve screw until the discharge gage just reaches the maximum value and stops moving. Back off until discharge pressure just starts to drop, then slowly readjust to maximum and st
- Tighten the adjusting screw locknut. Slowly increase supply air pressure until 14-18 psi (97-124 kPa) is reached; discharge pressure should read zero. Readjust as needed to obtain the required calibra
Tools required
- Two 0-40 psi (0-276 kPa) gages Amazon
- 0-100 psi (0-689 kPa) air pressure regulator Amazon
- Shop air approximately 100 psi (689 kPa) Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Maximum air delivery set to occur between 6 and 9 psi (41.4 and 62.1 kPa)
- Valve cut off between 9 and 14 psi (62.1 and 97 kPa)
- Supply side pressure 10 psi (69 kPa)
- Supply pressure increased to 14-18 Amazon eBay FridayParts $389.00 psi (97-124 kPa)
Source: Detroit Diesel service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.