EGR System - Checking/Adjusting
85volvo03SECTION GROUP NO.
23 124
DATE NOVEMBER, 1985 RE:
D24T EGR SYSTEM CHECKING/ADJUSTING
740/760 Turbo Diesel 1984 Calif. 1985-1986 All
THIS BULLETIN APPLIES TO THE U.S. AND CANADA. This information describes D24T EGR System operation and should be used for fault tracing, repairs, or whenever replacing/install ing the injection pump.
SYSTEM COMPONENTS
CHECKING/ADJUSTING EGR
Check all hoses and connectors A1
Disengage cold start device A2
- Loosen screw 1, push lever forward and turn sleeve 90~.
NOTE: DO NOT TOUCH screw 2. If this screw is loosened, cold start device must be re-set on test bench.
- Press lever rearward, against the stop.
- Connect a test lamp across + terminal on A3 solenoid valve and ground.
- Connect a vacuum gauge across EGR valve and the yellow hose.
Check idle switch A4
- Switch ignition ON. Test lamp should illuminate when pump lever rests on its stop. If not; check:
fuse # 11 1984 M/Y
fuse # 13 1985--M/Y
Check EGR time relay for proper delay time A5
- Move pump lever until test lamp goes out and hold arm in this position until test lamp illuminates again.
NOTE: Automatic transmission vehicles use EGR time relay, Part No. 1348422-6, which delays for approximately 4 seconds; manual transmission vehicles use EGR time relay, Part No. 1348294-8, which delays for approximately 5 seconds.
Check that test lamp is out when 5th gear (overdrive) is engaged.
- Switch ignition OFF.
Check idle switch setting A6
- Move pump lever until switch clicks.
- Hold pump lever in that position and measure clearance between screw and stop for low idle speed.
Correct clearance: 2-4 mm (0.08-0.16").
Use gauge tool 5285 when adjusting clearance.
NOTE: Tool 5285 is available from your RSM on a limited basis until mandatory distribution is performed during Jan. 1986
Adjust low idle switch A7
- Insert gauge tool (3 mm = 0.12") between screw and stop for low idle speed.
- Loosen screw while holding low idle speed switch and turn switch until switch clicks.
- Tighten screw and recheck according to op. A6.
Check vacuum governor A8
- Disconnect gray hose at thermo-vacuum valve (hose ending at vacuum governor) and connect a vacuum pump with minimum 50 kPa = 7 psi = 14.25 in. hg capacity.
A9
Vacuum pump for AC system can be used.
- Cut an elbow fitting and connect hose disconnected at thermo-vacuum valve.
A10
Install gauge 5285 so that long part of tool aligns pump housing.
NOTE: Vacuum governor is removed in photo to make position clear.
- Switch ignition ON. A11
- Start vacuum pump. Gauge reading should be 38 + 1 kPa = 5.40 +/- 0.14 psi = 10.99 +/- 0.28 in. hg. If gauge reading is incorrect, loosen two screws holding vacuum governor and move it until correct reading is obtained.
- Switch ignition OFF.
- Switch off vacuum pump and remove gauge tool.
Check vacuum governor full load switch A12
- Switch ignition ON.
- Move pump lever; wait until test lamp illuminates again. Continue movement, read vacuum gauge when the full load switch breaks contact. Correct reading is 20 + 2 kPa = 2.45 + .25 psi = 4.98 + 0.5 in. hg.
- If incorrect: use screw on switch to adjust.
- Disconnect vacuum pump.
Check thermo-vacuum valve A13
- Reconnect cold start device.
- Reconnect connections and disconnect test lamp. Leave vacuum gauge connected.
- Start engine. Vacuum gauge should not indicate vacuum until engine has reached low operating temperature of approx. 45~C = 113~F.