Cylinder Head Assembly: Service and Repair

1. Disconnect battery ground cable and remove splash guard under engine. Disconnect exhaust pipe from transmission bracket, rear exhaust manifold, and front exhaust manifold.
2. Disconnect air cleaner cover, remove expansion tank cap, and disconnect lower radiator hose to drain coolant. Disconnect lower hose at cold start device and point down to drain remaining coolant.
3. Disconnect upper radiator hose and cold start device hose from cylinder head. Remove vacuum pump and plunger.
4. Remove fuel delivery pipes and plug all ends and connections to prevent entry of dirt. Absolute cleanliness is extremely important. All connections must be cleaned thoroughly before disconnecting.
5. Disconnect the following from cylinder head: wires for temperature gauge sender and glow plugs, wire harness for rear glow plug, return hose from rear injector, and temperature gauge sender wire holder.

Fig. 1 Engine at TDC and injection:

6. Remove valve cover, front and rear timing belt covers. Set engine to TDC and injection position (compression stroke) for No. 1 cylinder. Both No. 1 cylinder camshaft lobes should point up at equal angles and flywheel timing mark should be at zero (0), Fig. 1.
7. Remove timing belt shield using care to avoid washer on inner retaining screw from falling inside timing gear lower cover.
8. Loosen retaining bolts for coolant pumps and belt idler pulley and remove belt from camshaft gear.
9. Using wrench 5199 or equivalent to hold gear, tap gear loose from camshaft. Do not allow camshaft to rotate.
10. Loosen injection pump bracket bolts to release belt tension and remove belt.
11. Using wrench 5199 or equivalent and wrench 5201 or equivalent to loosen bolt, remove camshaft rear gear. Camshaft must not be allowed to rotate.

Fig. 2 Cylinder head bolt tightening sequence:

12. Remove cylinder head bolts in reverse of tightening sequence, Fig. 2. Make sure that rear glow plug clears injection pump bracket and that valves do not contact cylinder walls.
13. Remove cylinder head and place on wooden blocks. Do not allow cylinder head to rest on valves. Clean gasket surfaces and check cylinder head for warpage, using steel rule and feeler gauge. Clearance should not exceed 0.008 inch lengthwise and 0.002 inch crosswise. Cracks between valve seats do not require replacement of cylinder head as long as they do not exceed 0.02 inch.
14. Reverse procedure to install, noting the following:
a. Three sizes of head gaskets are available as indicated by 1, 2, or 3 notches on the tab adjacent to the No. 2 cylinder opening in the gasket. Number of notches must be the same as old gasket if pistons, connecting rods or crankshaft assemblies have not been disturbed. If pistons, connecting rods, or crankshaft have been replaced or serviced, piston projection above cylinder block face must be measured and a new gasket selected. For a piston projection of 0.026-0.031" use a gasket with a thickness of 0.055" (1 notch), for a piston projection of 0.032-0.035" use a gasket with a thickness of 0.059" (2 notches), and for a piston projection of 0.036-0.040" use a gasket with a thickness of 0.063" (3 notches).
b. If cylinder head bolts are 11 mm diameter, torque cylinder head according to sequence in Fig. 2, in two steps: first to 30 ft. lbs. and then to 65 ft. lbs.
c. If cylinder head bolts are 12 mm diameter, torque cylinder head bolts in steps as follows: Step 1, torque bolts in sequence, Fig. 2, to 30 ft. lbs., then 44 ft. lbs. and finally 55 ft. lbs. Step 2, tighten bolts 1/2 additional turn with continuous motion. Step 3, run engine until oil temperature reaches 120°F., then tighten bolts 1/4 additional turn with continuous motion.
d. Refer to "Timing Belts, Replace" to set camshaft position.
e. Refer to "Injection Pump Setting" to set pump.
f. Torque fuel delivery pipes to 18 ft. lbs.