Usage:
Caterpillar Machines Powered By 3114 Or 3116 Machine Engines
Reference: Service Magazine; January 25, 1993; Page 23; "Unit Injector Tip Seal Deterioration"
Description of Change: In some cases the deterioration of the O-ring seal at the bottom of the unit injector has been reported as the cause of combustion leakage around the injector. See the Reference Article.The purpose of this seal is to provide initial sealing until the unit injector seats in the 7W-5749 Sleeve (brass) in the cylinder head. When assembled correctly the injector seats in the sleeve almost immediately after the initial engine start up. And it is normal for this O-ring seal to deteriorate over time due to exposure to the hot combustion gasses.
A new O-ring seal (black in color) is used in this area. The former O-ring seal was brown in color. The new O-ring seal will better withstand the high temperatures in this area. The new O-ring seal will also deteriorate, but at a slower rate than the former O-ring seal. This will allow more time for the injector to become seated in the brass sleeve.
Location of the new 125-8274 O-Ring Seal on the unit injector tip.
Adaptable To: The new 125-8274 O-Ring Seal (black) is a direct replacement for the 32-8970 O-Ring Seal (brown) in this application.