Engine Inspection and Repair
Fig. 14 Checking cylinder head for warpage (Typical):
CYLINDER HEAD
Replace cylinder head assembly if there is any evidence of wear or damage. Measure cylinder head for distortion on the lower mating surfaces along the areas indicated in Fig. 14. Cylinder head distortion should not exceed .006 inch. If cylinder head distortion exceeds .006 inch, grind cylinder head or replace as necessary. Do not grind more than .008 inch from cylinder head.
Fig. 15 Checking manifold contact surface distortion. DOHC engine:
Before grinding cylinder head on DOHC engine, check sinking of valve seat, distortion of manifold contact surface, Fig. 15, camshaft oil clearance and camshaft endplay, replacing cylinder head as necessary.
On DOHC engine, replace cylinder head if height is not 5.268-5.276 inches.
VALVE & VALVE GUIDE
Inspect valve and valve guide for excessive wear or damage. Check valve head thickness. Intake valve head thickness should be .039 inch on 1986-87 models, or .020 inch on 1988 models. Exhaust valve head thickness should be .051 inch on 1986-87 models, .039 inch on 1988 SOHC engine or .20 inch on DOHC engine. Measure valve stem diameter and valve stem clearance. If measurements obtained are not to specifications, replace valve and/or valve guide.
Fig. 16 Checking valve spring angle limit:
VALVE SPRING
Inspect each valve spring for cracks or damage. Check spring free length and spring angle. Spring free length should be 1.673 inch for 1986 models, 1.717 inch for 1987 models, 1.720 inch for 1988 SOHC engines or 1.858 inch for 1988 DOHC engine. Check spring angle limit as shown in Fig. 16. Angle limit should be .055 inch for 1986 models, .059 inch for 1987-88 SOHC engine or .063 inch for DOHC engine. Replace valve spring if measurements obtained exceed specifications.
Fig. 17 Valve seat angles:
VALVE SEAT
Inspect contact surfaces of the valve seat and valve face for excessive roughness and/or damage. If necessary, cut valve seat using a suitable valve seat cutter or grinder of 15, 35, 45, 70 and 75 degrees, Fig. 17. Intake and exhaust seat angle should be 45 degrees. Valve seat contact width should be .043-.067 inch on SOHC engine or .031-.055 inch on DOHC engine. Use suitable compound to seat the valve and valve seat. Ensure that the contact surface is at the center of the valve face. Replace the valve seal if the valve was cut.
CAMSHAFT(S)
Check camshaft assembly for wear and/or damage, replacing as necessary.
1. Place front and rear journals on V-blocks and, using dial indicator, ensure runout does not exceed .0012 inch.
2. Check cam lobe height in two places. Height should be 1.432-1.438 inch for SOHC engine. For DOHC engine, height of intake should be 1.6098 inch and height of exhaust should be 1.6019 inch.
Fig. 20 Measuring wear of camshaft journal. 1988:
3. Measure wear of journals in A and B directions at two places shown, Fig. 20. On SOHC engine, diameter of front and rear should be 1.7102-1.7112 inch and diameter of center should be 1.7091-1.7100 inch. On DOHC engine, diameter of Nos. 1-5 should be 1.0213-1.0222 inch and diameter of No. 6 should be 1.3370-1.3386 inch. Out of round should not exceed .002 inch.
4. On SOHC engine, measure oil clearances between camshaft and cylinder head as follows:
a. Remove oil or dirt from journals and camshaft bore.
b. Measure camshaft bore diameter, which should be 1.7126-1.7135 inch.
c. Subtract journal diameter from bore diameter. Front and rear clearance should be .0013-.0033 inch and center clearance should be .0026-.0045 inch.
5. On DOHC engine, measure oil clearances between camshaft and cylinder head as follows:
a. Remove any oil or dirt from journals and bearing surface.
b. Set camshaft on cylinder head. Do not install hydraulic lash adjuster when measuring oil clearance.
c. Position Plastigage on top of journal in journal axial direction.
Fig. 21 Camshaft cap bolt tightening sequence. DOHC engine:
d. Install camshaft caps according to cap number and arrow, then torque them to 100-126 inch lbs. in order shown, Fig. 21.
e. Loosen camshaft cap bolts in reverse order of tightening sequence.
f. If oil clearance exceeds .0059 inch, replace camshaft or cylinder head as necessary.
6. Using dial indicator, measure camshaft endplay, which should be .0020-.0071 inch. If endplay exceeds .0079 inch, replace thrust plate or camshaft.
ROCKER ARM & ROCKER ARM SHAFT
Inspect contact surfaces of rocker arm and rocker arm shaft for excessive wear and/or damage. Replace rocker arm and rocker arm shaft, if necessary. Using a micrometer, measure clearance between rocker shaft and rocker arms. Clearance should be .004 inch. The oil holes on the rocker arm shaft must be assembled in the down position.
Fig. 22 Checking cylinder block for warpage:
CYLINDER BLOCK
Inspect cylinder block for leakage damage, cracks and cylinder wall scoring. Repair or replace cylinder block, if necessary.
Measure cylinder block top surface distortion (warpage) in six directions as shown in Fig. 22. Distortion limit should be .006 inch. If distortion exceeds specified limit, grind top surface of cylinder block or replace cylinder block assembly. When grinding, do not grind more than .008 inch from top surface of cylinder block assembly.
Check cylinder walls. If upper portion of cylinder wall(s) indicate uneven wear, use a suitable ridge reamer to repair.
Fig. 23 Measuring cylinder bore at six locations:
Measure cylinder diameter at six locations indicated in Fig. 23. Standard cylinder diameter should be 3.0709-3.0717 inch. Cylinder diameter limit should be 3.0776 inch. Cylinder diameter difference should be .0007 inch. If the difference between the maximum and minimum range of the standard cylinder diameter exceeds the limit, rebore cylinder. The cylinder boring size should be based on the size of an oversize piston to be used.
PISTON & PISTON RING
Inspect outer circumferences of all pistons for seizure or scoring. Replace, if necessary. Measure outer diameter of each piston and ensure clearance between piston and cylinder is correct. Standard diameter should be 3.0691-3.0699 inch for 1986 models, 3.0691-3.0694 inch on 1987 models or 3.0690-3.0698 inch on 1988 models. Standard piston and cylinder clearance should be .006 inch on SOHC engine and .0010-.0026 inch on DOHC engine. Oversize piston and piston ring should be .010 inch oversize or .020 inch oversize.
Inspect piston rings for excessive wear and/or damage. Replace, if necessary. Insert piston ring into cylinder bore by hand and push inward using a piston. Using a suitable feeler gauge, measure piston ring end gap (clearance). Top ring clearance should be .008-.016 inch for 1986 and 1988 models or .006-.012 inch for 1987 models. Second ring clearance should be .006-.012 inch. Oil ring clearance should be .012-.035 inch for 1986 models or .008-.028 inch on 1987-88 models.
Measure clearance of the piston ring and groove around the entire circumference. Top and second ring clearance should be .001-.003 inch.
CONNECTING ROD
Check connecting rods for bends or twists. Replace connecting rod(s) if bends or twists are excessive.
Fig. 24 Checking crankshaft fillet R dimension. SOHC engine:
Fig. 25 Checking crankshaft fillet R dimension. DOHC engine:
CRANKSHAFT
Check crankshaft journals and pins for damage, scoring or oil hole restrictions. Using a suitable dial indicator, check crankshaft deflection. Deflection should not exceed .0016 inch. Measure each journal diameter and crankpin. Main journal diameter should be 1.9662-1.9668 inch. Crankpin diameter should be 1.7693-1.7699 inch. If crankshaft wear exceeds standard limit, grind crankshaft to match an undersized bearing, with attention to each crank fillet R dimension, Figs. 24 and 25. Crankshaft grinding limit is .0295 inch on SOHC engine or .50 inch on DOHC engine. Undersize bearings available are .010 inch, .020 inch and .0295 inch for SOHC engine and .25 and .50 inch for DOHC engine. Crankshaft fillet R dimension is .012 inch on SOHC engine and .059 inch on DOHC engine.
TIMING BELT
Replace timing belt if there is any oil grease or moisture on it. Check timing belt from damage, wear, peeling, cracks or evidence or hardening. Replace, if necessary. Never forcefully twist the timing belt or turn the timing belt inside out or bend it. Ensure not to allow oil, grease or moisture to contact timing belt assembly.
TIMING BELT TENSIONER
Check rotation of the timing belt tensioner for smoothness or abnormal noise. Replace timing belt, if necessary. Do not clean the timing belt tensioner with cleaning fluids. If timing belt is dirty, use a soft shop towel to wipe it clean and avoid scratching it.
CAMSHAFT PULLEY & TIMING BELT PULLEY
Inspect pulley teeth for excessive wear and/or damage. Replace pulley, if necessary. Do not clean the pulley with cleaning fluids. If pulley if dirty, use a soft shop towel to wipe it clean.
UPPER, MIDDLE (DOHC ENGINE) & LOWER TIMING BELT COVERS
Inspect timing belt covers for excessive wear and/or damage. Replace covers, if necessary.