COLUMN AS 6W0251 - Caterpillar

D353, D379, D398, D399 EnginesReference: This article is a revision of the article "New Exhaust Valve and Valve Guide" on Page 5 of the February 19, 1979, Service Magazine. Cancel the original article and use this information instead.Description of Change: A new exhaust valve is available for the above engines used in special applications. The new valve is made of a different material for better heat resistance in conditions of high temperature operation. With the change of material, the stem of the new valve is not chrome plated (does not have a layer of chrome on the surface). For this reason, the new valve can be used with the standard valve guide; the special guide used with the former valve is not needed. The standard 8H7097 Exhaust Valve and 6N8847 Valve Guide (Exhaust) used for original factory installation are not changed.Adaptable As: Direct replacement. For special applications, use the new 8N3723 Exhaust Valve and standard 6N8847 Exhaust Valve Guide in place of the former 4N6883 Exhaust Valve (which is canceled) and the special 2N5801 Valve Bushing (guide). The new valve is available only for parts service replacement in applications where high temperatures shorten valve service life.