1.2.2
Exhaust Valves
DETROIT DIESEL 53
Fig. 7 - Removing Valve Seat Insert
J 7774 (four valve head) inside the valve insert so that
the bottom of the collet is flush with the bottom of the
insert.
3. Hold the collet handle and turn the T handle to
expand the collet cone until the insert is held securely
by the tool.
4. Insert the drive bar of the tool through the valve
Fig. 8 - Installing Valve Seat Insert
guide.
oversize on the outside diameter are available.
5. Tap the drive bar once or twice to move the insert
if required.
about 1/16 " away from its seat in the cylinder head.
3. Immerse the cylinder head for at least 30 minutes in
6. Turn the T handle to loosen the collet cone and
water heated to 180 oF to 200 oF.
move the tool into the insert slightly so the narrow
flange at the bottom of the collet is below the valve
4. Rest the cylinder head, bottom side up. on a bench
seat insert.
and place an insert in the counterbore--valve seat side
up. This must be done quickly while the cylinder head
7. Tighten the collet cone and continue to drive the
is still hot and the insert is cold (room temperature). If
insert out of the cylinder head.
the temperature of the two parts is allowed to become
nearly the same, installation may become difficult and
damage to the parts may result.
Install Exhaust Valve Seat lnsert
5. Drive the insert in place with installer
J 7790 (four valve head) as shown in
1. Clean the valve seat insert counterbores in the head
Fig. 8 until it seats solidly in the cylinder head.
with trichloroethylene or other suitable solvent. Also
wash the valve seat inserts with the same solvent. Dry
6. Grind the valve seat insert and check it for
the counterbores and the inserts with compressed air.
concentricity in relation to the valve guide as outlined
below.
2. Inspect the counterbores for cleanliness, concentric-
ity, flatness and cracks.
Recondition Exhaust Valve and Valve Seat
The counterbores in a four
lnsert
valve head have a diameter of 1.159 " to 1.160 " and a
depth of .294 " to .306 " on former engines and a
An exhaust valve which is to be reused may be
depth of .300 " to .312 " on current engines.
refaced, if necessary (Fig. 9). To provide sufficient
valve strength and spring tension, the edge of the
NOTE: Valve seat inserts which are .010 "
SEC. 1.2.2 Page 5
August, 1972
