Mazda MX-5 Miata (1997+). Manual - part 59

Valves 

Check valve face angle, head diameter, margin thickness and stem diameter. Service or replace valves if 
measurements are not within specifications. See VALVES & VALVE SPRINGS under ENGINE 
SPECIFICATIONS. 

Valve Seat Correction Angles 

Measure seat contact width on valve. See VALVE SEAT. If seat width is not within specification or if valve 
face does not contact center of valve seat, correct seat using a 70-degree grinding stone. After correcting seat, 
lightly finish seat with 45-degree grinding stone. 

VALVE TRAIN 

Hydraulic Lash Adjusters 

1. Remove camshaft cover. Check movement of each Hydraulic Lash Adjuster (HLA) by pushing 

downward using hand pressure only. If HLA compresses, replace HLA. To remove HLA, remove 
camshafts. See CAMSHAFT under REMOVAL & INSTALLATION. Mark location of HLA before 
removing from bore. Lift HLA from cylinder head. 

2. Inspect HLA friction surfaces for wear and damage. Replace HLA if required. Coat HLA with engine oil 

and install in original location. Ensure HLA moves smoothly in bore by using small magnet attached to 
HLA.  

CYLINDER BLOCK ASSEMBLY 

Piston & Connecting Rod Assembly 

1. Before removing rod cap from crankshaft, measure and record rod side play. See CONNECTING RODS

under ENGINE SPECIFICATIONS. Before removing connecting rods, measure and record connecting 
rod bearing oil clearance. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS under 
ENGINE SPECIFICATIONS.  

2. Before separating piston from connecting rod, mark piston in relation to connecting rod. Check 

oscillation movement of piston and rod assembly (hold piston horizontally, lift rod and allow rod to drop 
by its own weight). If pin binds in pin bore (rod does not drop), replace piston and/or pin as necessary.  

3. To separate components, press piston pin out of piston and rod assembly, noting pressure required to 

Normal

1.772-1.791 (45.00-45.50)

Serviceable

1.733-1.772 (45.60-46.50)

NOTE:

If hydraulic lash adjusters are persistently noisy, check with manufacturer 
for availability of modified adjusters.

NOTE:

During disassembly, match mark components for reassembly reference.

 

1997 Mazda MX-5 Miata 

1997-98 ENGINES 1.8L 4-Cylinder

  

remove piston pin. If piston pin can be pressed out with less than 1100 lbs. (500 kg) of pressure, replace 
piston and/or connecting rod.  

4. Ensure piston pin diameter, piston fit and rod fit are within specification. See PISTONS, PINS & 

RINGS under ENGINE SPECIFICATIONS. Using 1100-3300 lbs. (500-1500 kg) of pressure, install 
piston pin through side of piston that has an "F" mark near pin bore. See Fig. 18 . Install piston and rod 
assembly so "F" mark on side of piston is facing front of engine.  

Fig. 18: Installing Piston & Connecting Rod Assembly 
Courtesy of MAZDA MOTORS CORP. 

 

1997 Mazda MX-5 Miata 

1997-98 ENGINES 1.8L 4-Cylinder

  

Fitting Pistons 

1. Ensure pistons are not scored or damaged. Measure piston diameter on piston skirt at 90-degree angle 

from piston pin, .65" (16.5 mm) below lowest ring groove. See PISTONS, PINS & RINGS under 
ENGINE SPECIFICATIONS.  

2. Check piston-to-cylinder wall clearance in 3 different vertical places of piston travel. If clearance is not 

within specification, re-bore cylinders to fit oversize pistons. Using NEW piston rings, measure piston 
ring side clearance around entire piston circumference. If clearance is not within specification, replace 
piston. See PISTONS, PINS & RINGS .  

Piston Rings 

1. If ring end gap and side clearance are not within specification, replace piston and/or rings as necessary. 

See PISTONS, PINS & RINGS under ENGINE SPECIFICATIONS.  

2. Install oil ring spacer. Ensure ends DO NOT overlap. See Fig. 19 . Upper and lower rails are the same 

and are interchangeable. In stall rails, ensuring rails are expanded by spacer tangs (oil rings when 
assembled should rotate freely). Install rings No. 1 (top) and No. 2 (second) with "R" mark toward top of 
piston. Ensure ring end gaps are properly positioned around piston. See Fig. 20 .  

Fig. 19: Identifying Oil Rings 

NOTE:

Pistons and rings are available in .010" (.25 mm) and .020" (.50 mm) oversize.

 

1997 Mazda MX-5 Miata 

1997-98 ENGINES 1.8L 4-Cylinder

  

Courtesy of MAZDA MOTORS CORP. 

Fig. 20: Identifying Piston Rings & Positioning Ring End Gaps 
Courtesy of MAZDA MOTORS CORP. 

Crankshaft & Main Bearings 

1. Check crankshaft connecting rod journals for wear, out-of-round, taper and undersize. Machine or replace 

crankshaft and/or bearings as necessary. See CRANKSHAFT, MAIN & CONNECTING ROD 
BEARINGS under ENGINE SPECIFICATIONS.  

2. Before removing main cap, measure and record crankshaft end play by prying crankshaft forward, then 

rearward. Using Plastigage method, measure and record main bearing oil clearance. Remove crankshaft. 
Measure and record each main journal diameter in 2 places. See CRANKSHAFT, MAIN & 
CONNECTING ROD BEARINGS under ENGINE SPECIFICATIONS. 

 

1997 Mazda MX-5 Miata 

1997-98 ENGINES 1.8L 4-Cylinder