Bronco L6-300 4.9L VIN Y 1-bbl (1983)
EGR Valve: All Technical Service Bulletins
EGR Valve/Engine - Piston Slap Noise
Article No. 83-23-14-S
NOISE - PISTON SLAP - (4.9L) COLD DRIVEAWAY UNDER LIGHT LOAD
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VEHICLES UNDER 8500 LB. GVW
LIGHT TRUCKS 1981-83 E & F-SERIES & BRONCO
CALIBRATIONS: All (3-52F, 3-52G, 3-52K, 3-52S, 3-52T, 3-52V should only use Step B)
This is a re-issue and supplement to TSB 83-23-14, dated November 15, 1983. Revised pistons are now available in .020, .030 and .040 oversize for use
in engine overhauls.
Some units may experience a piston slap noise during cold engine high speed and light load conditions. The noise will usually occur within the first 2
miles of operation. The following procedures should resolve this concern. Perform vacuum schematic changes as noted for cold drive trickle EGR. Then,
if necessary, replace pistons if the concern is not resolved.
Step A
All 1981-83 vehicles except 1983 AOD calibrations 3-52F, 3-52G, 3-52K, 3-52S, 3-52T, 3-52V. These calibrations should only use Step B.
FIGURE 36
1.
Assemble a vacuum harness as shown in Figure 36.
2.
Locate the EGR valve and remove the vacuum hose from the valve and connect it to the "C" end of the harness assembly.
3.
Connect the "B" end of the harness assembly to the EGR valve.
4.
Remove the hose from the carburetor EGR port and connect the "A" end of the harness to the EGR port.
5.
Connect the hose that was removed from the EGR port to the other side of the "A" end of the harness.
