Article 2091 - New Pistons and Piston Rings to Improve Oil Economy

TSB #132 - January 30, 1970
(All Medium, Heavy and Extra-Heavy Trucks with 330, 361 and 391 C.I.D. Engines - 1970)


To improve oil economy on the 330, 361 and 391 C.I.D. engines, the pistons and rings on the 1970 models were changed as follows:

    - Piston: Full dish combustion chamber and upper ring groove changed from 5/64 width to 3/32 width.
    - Rings: Upper compression ring, 3/32 width straight faced with .006 chrome. Second and Third compression rings, phosphate coated with scraper face. Oil control ring is cast iron type 85 chrome plated with hump type expander. The new pistons can be installed in previous engines, however, the new upper compression ring will not fit in previous engines due to change in ring groove.

PARTS:
Part Number Part NameClassAvail.
D0TZ-6108-AG Piston 391 StdAOK
D0TZ-6108-AJ391 .003-OS B OK
D0TZ-6108-AK391 .020-OSCOK
D0TZ-6108-AL391 .030-OS C OK
D0TZ-6108-AM 391 .040-OS C OK
D0TZ-6108-APiston 361 Std A OK
D0TZ-6108-C 361 .003-OS C OK
D0TZ-6108-D 361 .020-OS A OK
D0TZ-6108-E 361 .030-OS A OK
D0TZ-6108-F 361 .040-OS B OK
D0TZ-6108-ZPiston 330 StdA OK
D0TZ-6108-AB 330 .003-OSCOK
D0TZ-6108-AC330 .020-OS B OK
D0TZ-6108-AD330 .030-OSA OK
D0TZ-6108-AE 330 .040-OS C OK
D0TZ-6148-ARing Set 361-391 StdAOK
D0TZ-6148-B361-391 .020-OS B OK
D0TZ-6148-C 361-391 .030-OS B OK
D0TZ-6148-D361-391 .040-OSBOK
D0TZ-6148-E330 StdA OK
D0TZ-6148-F330 .020-OSB OK
D0TZ-6148-G330 .030-OS B OK
D0TZ-6148-H330 .040-OSCOK


PRODUCTION CORRECTION: November 10, 1969.
WARRANTY STATUS:
INFORMATION ONLY

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