GASKET 3848285 - Caterpillar

Instructions for field conversion.This manifold is also adaptable for field conversion of 3406 Engines with Serial Numbers 90U1-up, 92U1-up, and 70V1-up.
The parts in the factory change are shown in Chart A.
The parts needed for the field conversion are shown in Chart B.
Field Conversion
For a field conversion, it is necessary to make a modification of the former 4N9049 Inlet Manifold. The steps for the modification follow: 1. Drill the two end bolt holes through with a 27/64" drill.2. Retap (cut threads again) the other bolt holes with a 3/8-16 bottom tap.3. Machine the flange (spot face) or use a file on the top side of the two end bolt bosses, so the washer will have a flat seat. But do not decrease the thickness of the manifold in this area to less than .5" (13 mm). Also, be careful not to make a sharp corner in the area shown in the illustration.4. Install the manifold with new 6N8204 Gaskets and the longer bolts (S1590 and S1591).