Engine - New Type Oil Gallery Plugs

Bulletin No. T 84-58
File In Group 6A
Number 57
Date Mar. '84
SUBJECT: HT4100 OIL GALLERY PLUGS

MODELS AFFECTED: 1983-1984 "C, E, K, D"

Oil Gallery Plugs Locations:

To reduce oil leaks, two new engine oil gallery plugs, available through GMWDD (P/N 1628880, 1/2 NPTF, and P/N 1628881, 3/8 NPTF), have been released for production on late 1983 and 1984 HT4100 engines, starting with engine unit number T10L080783. These new gallery plugs, which are phosphate treated and then coated with a specific sealer, may require the use of light heat for removal.

These new gallery plugs have proven to be superior to any other plug currently available and should be used when servicing all HT4100 engines for oil leaks in these areas (refer to figure).