GM Cadillac 1967-1989 Repair Guide

Cylinder Head

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10

Care must be used when replacing Cadillac engine cylinder head bolts. They are different lengths. Mark them during removal so they may be installed in their original position..

Most engines described in this guide use hydraulic lifters, which require no periodic adjustment. In the event of cylinder head removal or any operation that requires disturbing the rocker arms, the rocker arms will have to be adjusted. Refer to Valve Lash Adjustment later in this Section.

V8 Engines Except 8-307 Eldorado and Seville with 8-250 and 8-273 Engines

  1. Disconnect the battery.
  2.  
  3. Drain the coolant and save it if still fresh.
  4.  
  5. Remove the air cleaner.
  6.  
  7. Remove the air conditioning compressor, but do not disconnect any air conditioning lines. Secure the compressor to one side.
  8.  
  9. Disconnect the AIR hose at the check valve.
  10.  
  11. Remove the intake manifold.
  12.  
  13. When removing the right cylinder head, loosen the alternator belt, disconnect the wiring and remove the alternator.
  14.  
  15. When removing the left cylinder head, remove the dipstick, power steering pump and air pump if so equipped.
  16.  
  17. Label the spark plug wires and disconnect them.
  18.  
  19. Disconnect the exhaust manifold from the head being removed.
  20.  
  21. Remove the valve cover. Scribe the rocker arms with an identifying mark for reassembly; it is important that the rocker assembly is reinstalled in the same position as it was removed. Remove the rocker arm bolts, rocker arms and pivots or rocker arm assemblies.
  22.  
  23. Take a piece of heavy cardboard and cut 16 holes (or 8 holes if you are only removing one head) in it the same diameter as the pushrod stem. Number the holes in relation to the pushrods being removed. This cardboard holder will keep the pushrods in order (and hopefully out of harm's way) while they are out of the engine. Remove the pushrods.
  24.  

Pushrods MUST be returned to their original locations.

  1. Install two 7 / 16 -14 x 6 in. bolts to be used as lifting handles in two of the rocker arm support screw holes.
  2.  
  3. Remove the cylinder head bolts, noting the different sizes and locations and remove the cylinder head and gasket. If the head seems stuck to the block, gently tap around the edge of the head with a rubber mallet until the joint breaks.
  4.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces.
  2.  
  3. Position the cylinder head gasket over the dowels on the cylinder block.
  4.  
  5. Position the cylinder head on the block.
  6.  
  7. Install the cylinder head bolts finger tight in all locations. Tighten the bolts in sequence and to the torque value in the Torque Specification Chart.
  8.  
  9. Remove the two 7 / 16 -14 x 6 in. lifting bolts.
  10.  
  11. Install the pushrods through the openings in the cylinder head. The bottom of the pushrod must be seated in the hydraulic valve lifter cup.
  12.  
  13. Install the rocker arm assemblies on the cylinder heads in the same positions as found during disassembly and tighten the retaining screws to 60 ft. lbs. (81 Nm).
  14.  
  15. Install the rocker arm cover.
  16.  
  17. Install the intake and exhaust manifolds as described earlier.
  18.  
  19. When installing the left cylinder head, install the dipstick, power steering pump and air pump if so equipped.
  20.  
  21. When installing the right cylinder head, install the alternator, belt, and connect the wiring.
  22.  
  23. Refill the cooling system and check for leaks.
  24.  

6-250 Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the intake manifold-to-engine bolts and the manifold as outlined earlier.
  4.  
  5. Loosen and remove the drive belt(s).
  6.  
  7. When removing the left cylinder head, remove the oil dipstick, the air pump (if equipped) with the mounting bracket and move it aside with the hoses attached.
  8.  
  9. When removing the right cylinder head, remove the alternator, disconnect the power steering gear pump and the brackets.
  10.  
  11. Label and disconnect the spark plug wires; remove the spark plug wire clips from the rocker arm cover studs.
  12.  
  13. Remove the exhaust manifold-to-cylinder head bolts.
  14.  
  15. Using an air hose and/or cloths, clean the dirt from the cylinder head and adjacent area to avoid getting dirt into the engine.
  16.  
  17. Remove the rocker arm cover and the rocker arm/shaft assembly from the cylinder head. Lift out the push rods.
  18.  
  19. Loosen the cylinder head-to-engine bolts, then, remove the bolts and the cylinder head.
  20.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces.
  2.  
  3. Apply graphite lubricant to the exhaust manifold faces of the cylinder head.
  4.  
  5. Install a new head gasket over the dowels on the cylinder block.
  6.  
  7. Install the cylinder head bolts finger tight with the stud-headed bolts in the upper row and the conventional bolts in the lower row. Torque the bolts in the sequence shown and to the value listed in the Torque specification Chart.
  8.  
  9. Reinstall the intake and exhaust manifolds
  10.  

Eldorado and Seville With 8-250 (1982-87)
  1. Disconnect the negative battery cable. Drain the engine coolant.
  2.  
  3. Remove the intake and exhaust manifolds.
  4.  
  5. Disconnect all electrical and ground connections from the cylinder head.
  6.  
  7. When removing the left cylinder head, partially remove the power steering pump.
  8.  
  9. When removing the right cylinder head, remove the alternator and the heater hose from the rear of the head.
  10.  
  11. Remove the air pump, if equipped.
  12.  
  13. Remove bolts holding the rocker arm cover to the heads and remove the cover.
  14.  
  15. Remove nuts holding the rocker arm support to cylinder head, then remove the support and rocker arm assemblies. Store these assemblies so that they may be reinstalled in their correct locations.
  16.  
  17. Remove the pushrods and store them with their respective rocker arm assemblies.
  18.  
  19. Remove the cylinder head bolts.
  20.  
  21. Lift the cylinder head off of the block.
  22.  

Install cylinder liner holders to prevent loss of the bottom seal.

To install:
  1. Using a putty knife, clean the gasket mounting surfaces.
  2.  
  3. Apply graphite lubricant to the exhaust manifold faces of the cylinder head.
  4.  
  5. Install a new head gasket over the dowels on the cylinder block.
  6.  
  7. Install the cylinder head bolts finger tight. Torque the bolts in the sequence shown and to the value listed in the Torque specification Chart.
  8.  
  9. Reinstall the intake and exhaust manifold as described earlier.
  10.  
  11. Refill the cooling system.
  12.  
  13. Reinstall the air pump and power steering pump, if removed.
  14.  
  15. Connect the battery cable.
  16.  

8-250 and 8-273 Engines (1988-89)

LEFT



  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove the rocker arm covers.
  6.  
  7. Remove the intake manifold-to-engine bolts and intake manifold.
  8.  
  9. Disconnect the exhaust manifold crossover pipe, the exhaust pipe-to-exhaust manifold bolts, the exhaust manifold-to-cylinder head bolts and the exhaust manifold.
  10.  
  11. Remove the engine lifting bracket and the dipstick tube.
  12.  
  13. Remove the AIR bracket-to-engine bolts and move the bracket aside.
  14.  
  15. Remove the cylinder head-to-engine bolts and the cylinder head.
  16.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces.
  2.  
  3. Install a new head gasket over the dowels on the cylinder block use sealant (if necessary).
  4.  
  5. Apply GM lubricant No. 1052356 or equivalent, to the cylinder head bolt threads and install the cylinder head bolts finger tight. Torque the cylinder head bolts (in sequence) using three steps: 1st to 38 ft. lbs. (51 Nm), 2nd to 68 ft. lbs. (92 Nm) and 3rd to 90 ft. lbs. (122 Nm) for bolts No.1, 3 & 4. Check the Torque Specification Chart.
  6.  
  7. Reinstall the intake and exhaust manifolds as described earlier.
  8.  
  9. Refill the cooling system.
  10.  
  11. Reinstall the air pump bracket, if removed.
  12.  
  13. Connect the battery cable.
  14.  
  15. To complete the installation, reverse the removal procedures. Start the engine, allow it to reach normal operating temperatures and check for leaks.
  16.  

RIGHT
  1. Remove negative battery cable.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove the rocker arm covers.
  6.  
  7. Remove the intake manifold-to-engine bolts and intake manifold.
  8.  
  9. Disconnect the exhaust manifold crossover pipe, the exhaust pipe-to-exhaust manifold bolts, the exhaust manifold-to-cylinder head bolts and the exhaust manifold.
  10.  
  11. Remove the engine lifting bracket.
  12.  
  13. Remove the AIR bracket-to-engine bolts and move the bracket aside.
  14.  
  15. Remove the cylinder head-to-engine bolts and the cylinder head.
  16.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces.
  2.  
  3. Install a new head gasket over the dowels on the cylinder block use sealant (if necessary).
  4.  
  5. Apply GM lubricant No. 1052356 or equivalent, to the cylinder head bolt threads and install the cylinder head bolts finger tight. Torque the cylinder head bolts (in sequence) using three steps: 1st to 38 ft. lbs. (51 Nm), 2nd to 68 ft. lbs. (92 Nm) and 3rd to 90 ft. lbs. (122 Nm) for bolts No.1, 3 & 4. Check the Torque Specification Chart.
  6.  
  7. Reinstall the intake and exhaust manifold as described earlier.
  8.  
  9. Refill the cooling system.
  10.  
  11. Reinstall the air pump bracket, if removed.
  12.  
  13. Connect the battery cable.
  14.  
  15. To complete the installation, reverse the removal procedures. Start the engine, allow it to reach normal operating temperatures and check for leaks.
  16.  

8-307 Engine

CAUTION
Do not disconnect the air conditioning lines. Severe personal injury could result!

  1. Drain the cooling system.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the intake manifold and carburetor as an assembly.
  2.  
  3. Remove exhaust manifolds.
  4.  
  5. Loosen or remove any accessory brackets which interfere.
  6.  
  7. Remove the valve cover(s). Loosen any accessory brackets which are in the way.
  8.  
  9. Remove the battery ground strap from the cylinder head.
  10.  
  11. Remove cylinder head bolts and cylinder head(s).
  12.  
  13. Install in the reverse order of removal. It is not recommended that sealer be used on the new head gasket. Dip head bolts in oil before installing and allow them to drain so oil will not fill the threads and interfere with proper torquing. Tighten all head bolts in the correct sequence to 90 ft. lbs. (122 Nm), then torque, again in sequence, to 130 ft. lbs. (176 Nm) Retorque the bolts after engine is warmed up.
  14.  

8-350 Diesel Engine
  1. Remove the intake manifold, using the procedure outlined above.
  2.  
  3. Remove the rocker arm cover(s), after removing any accessory brackets which interfere with cover removal.
  4.  
  5. Disconnect and label the glow plug wiring.
  6.  
  7. If the right cylinder head is being removed, remove the ground strap from the head.
  8.  
  9. Remove the rocker arm bolts, the bridged pivots, the rocker arms, and the pushrods, keeping all the parts in order so that they can be returned to their original positions. It is a good practice to number or mark the parts to avoid interchanging them.
  10.  
  11. Remove the fuel return lines from the nozzles.
  12.  
  13. Remove the exhaust manifold(s), using the procedure outlined above.
  14.  
  15. Remove the engine block drain plug on the side of the engine from which the cylinder head is being removed.
  16.  

  1. Remove the head bolts. Remove the cylinder head.
  2.  

To install:
  1. Clean the mating surfaces thoroughly. Install new head gaskets on the engine block. Do NOT coat the gaskets with any sealer. The gaskets have a special coating that eliminates the need for sealer. The use of sealer will interfere with this coating and cause leaks. Install the cylinder head onto the block.
  2.  
  3. Clean the head bolts thoroughly. Dip the bolts in clean engine oil and install into the cylinder block until the heads of the bolts lightly contact the cylinder head.
  4.  
  5. Tighten the bolts, in the sequence illustrated, to 100 ft. lbs. (136 Nm). When all bolts have been tightened to this figure, begin the tightening sequence again, and torque all bolts to 130 ft. lbs. (176 Nm).
  6.  
  7. Install the engine block drain plugs, the exhaust manifolds, the fuel return lines, the glow plug wiring, and the ground strap for the right cylinder head.
  8.  
  9. Install the valve train assembly. Refer to the Diesel Engine Rocker Arm Replacement in this section for the valve lifter bleeding procedures.
  10.  
  11. Install the intake manifold.
  12.  
  13. Install the valve covers. These are sealed with Room Temperature Vulcanizing (RTV) silicone sealer instead of a gasket. Use GM #1052434 or an equivalent. Install the cover to the head within 10 minutes, while the sealer is still wet.
  14.  



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Fig. Fig. 1: Cylinder head removal - all engines



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Fig. Fig. 2: 6-252 engine head bolt torque sequence



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Fig. Fig. 3: Cylinder head bolt tightening sequence - 1982-85 8-250



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Fig. Fig. 4: Cylinder head bolt tightening sequence - 1986-89, 8-250, 8-273 engine



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Fig. Fig. 5: Cylinder head bolt tightening sequence - 8-307, 8-350 (gas engine)



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Fig. Fig. 6: Cylinder head bolt tightening sequence - 8-368, 425, 429, 472 and 500 cu. in. engines



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Fig. Fig. 7: Cylinder head bolt tightening sequence - 8-350 diesel engine



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Fig. Fig. 8: Removing the cylinder head assembly



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Fig. Fig. 9: Removing cylinder head gasket - always replace



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Fig. Fig. 10: View of the under side of a common the cylinder head

CYLINDER HEAD CLEANING & INSPECTION



Any diesel cylinder head work should be handled by a reputable machine shop familiar with diesel engines. Disassembly, valve lapping, and assembly can be completed by following the gasoline engine procedures.

Gasoline Engines Only

See Figures 11, 12 and 13

Once the complete valve train has been removed from the cylinder head(s), the head itself can be inspected, cleaned and machined (if necessary). Set the head(s) on a clean work space, so the combustion chambers are facing up. Begin cleaning the chambers and ports with a hardwood chisel or other non-metallic tool (to avoid nicking or gouging the chamber, ports, and especially the valve seats). Chip away the major carbon deposits, then remove the remainder of carbon with a wire brush fitted to an electric drill.

Be sure that the carbon is actually removed, rather than just burnished.

After decarbonizing is completed, take the head(s) to a machine shop and have the head hot tanked. In this process, the head is lowered into a hot chemical bath that very effectively cleans all grease, corrosion, and scale from all internal and external head surfaces. Also have the machinist check the valve seats and re-cut them if necessary. When you bring the clean head(s) home, place them on a clean surface. Completely clean the entire valve train with solvent.



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Fig. Fig. 11: Use a wire brush and electric drill to remove carbon from the combustion chambers and exhaust ports



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Fig. Fig. 12: Use a gasket scraper to remove the bulk of the old head gasket from the mating surface



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Fig. Fig. 13: An electric drill equipped with a wire wheel will expedite complete gasket removal

CHECKING FOR HEAD WARPAGE



See Figures 14, 15 and 16

Lay the head down with the combustion chambers facing up. Place a straightedge across the gasket surface of the head, both diagonally and straight across the center. Using a flat feeler gauge, determine the clearance at the center of the straightedge. If warpage exceeds 0.003 in. (0.08mm) in a 6 in. (152mm) span, or 0.006 in. (0.15mm) over the total length, the cylinder head must be resurfaced (which is akin to planning a piece of wood). Resurfacing can be performed at most machine shops.

When resurfacing the cylinder head(s) of V6 or V8 engines, the intake manifold mounting position is altered, and must be corrected by machining a proportionate amount from the intake manifold flange.



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Fig. Fig. 14: Check the cylinder head mating surface for warpage with a precision straight edge



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Fig. Fig. 15: Check the cylinder head for warpage along the center line using a straight edge and feeler gauge



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Fig. Fig. 16: Be sure to check for warpage across the cylinder head at both diagonals

 
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