Cylinder Head Installation Isuzu 4BD1/T Diesel Engines
Isuzu Truck of America recommends the following procedure when installing the cylinder head on 4BD1/T diesel engines.
Position the cylinder head gasket on the cylinder block with the TOP mark facing up and the FRONT mark facing forward. Lubricate the head bolts with engine oil on 4BD1 engines and tighten in two steps using the sequence outlined in the illustration below. Turbo charged 4BD1T engine head bolts should be lubricated with molybdenum disulfied grease before installation.
There are two different length head bolts used. Be sure to install the shorter length bolts on the injection pump side of the engine.
Engine Bolt Status Step 1 Step 2
4BD1 Reused 47-54 lbs.ft. 80-87 lbs.ft.
New 47-54 lbs.ft. 69-76 lbs.ft.
4BD1T N/A 50 lbs.ft. 65 lbs.ft. *
* Then turn each bolt an additional 90o-120o.
For additional information see AERA Bulletin: TB 628