Mazda MX-5 Miata (1997+). Manual - part 58

Courtesy of MAZDA MOTORS CORP. 

Removal & Installation (Protege) 

1. Disconnect negative battery cable. Remove engine undercovers. Drain engine oil. Remove exhaust header 

downpipe and brackets from front exhaust system. Remove oil pan retaining bolts.  

2. DO NOT damage sealant contact surfaces. Remove oil pan by prying between oil pan and mounting 

surface. On Protege, remove stiffener by prying between stiffener and cylinder block. On all models, 
clean all sealant from oil pan, bolts, engine block and both sides of stiffener (Protege). 

3. On Protege, apply oil resistant sealant to engine block and stiffener. Install stiffener. On all models, apply 

sealant and install oil pan within 5 minutes of applying sealant. To complete installation, reverse removal 
procedure. Tighten all bolts to specification. See TORQUE SPECIFICATIONS . Fill engine with oil to 
specification. See ENGINE LUBRICATION SYSTEM under ENGINE OILING.  

OVERHAUL 

CYLINDER HEAD 

Cylinder Head 

Clean carbon and gasket material from all mating surfaces. Using a tap, clean cylinder head threads. Check 
cylinder head warpage. If warpage exceeds specification, resurface head, but DO NOT exceed grinding limit. 
See CYLINDER HEAD under ENGINE SPECIFICATIONS. After resurfacing cylinder head, check cylinder 
head height. Replace cylinder head if height is less than minimum specification. 

Valve Springs 

Ensure valve spring free length, out-of-square and compressed length are within specification. See VALVES & 
VALVE SPRINGS under ENGINE SPECIFICATIONS. Replace valve spring if necessary. 

Valve Stem Oil Seals 

1. On Miata, use Installer Set (49-L012-0A0) to install valve seals. See Fig. 15 . Adjust installer dimension 

"L" to seal depth of .720-.744" (18.3-18.9 mm). Using hand pressure ONLY, install seal until it contacts 
cylinder head. Lightly oil valve seal lip.  

2. On Protege, use Installer Set (49-L012-0A0) to install valve seals. See Fig. 15 . Adjust installer 

dimension "L" to seal depth of .783" (19.9 mm). Using hand pressure, install seal until it contacts cylinder 

CAUTION: If reusing old oil pan bolts, remove old sealant from bolt threads. 

Failure to remove old sealant may result in cracked block at bolt 
holes.

NOTE:

Intake and exhaust valve stem seals are different. Exhaust seals can be 
identified by ridges molded into top of seal. Intake seals do not have identifying 
ridges. Incorrect installation of valve stem seals will cause premature failure.

 

1997 Mazda MX-5 Miata 

1997-98 ENGINES 1.8L 4-Cylinder

  

head. Lightly oil valve seal lip.  

Fig. 15: Installing Valve Guide Seals 
Courtesy of MAZDA MOTORS CORP. 

Valve Guides 

1. Check valve stem-to-valve guide oil clearance. Ensure valve guide inside diameter is within specification. 

See CYLINDER HEAD under ENGINE SPECIFICATIONS.  

2. Completely disassemble cylinder head. Gradually heat cylinder head in water to 194°F (94°C). Using 

Valve Guide Remover (49-B012-005), drive valve guide out, working from combustion chamber side of 
cylinder head. Repeat procedure if required, keeping cylinder head hot so aluminum head will not warp.  

3. If required, install new circlip on guide. Using proper components of Valve Guide Installer (49-L012-

0A0), adjust installer guide depth (dimension "L") to specification using depth micrometer or caliper. See 
VALVE GUIDE INSTALLED HEIGHT . See Fig. 16 .  

4. Insert guide into pre-adjusted installer and drive guide into cylinder head from camshaft side until guide 

circlip, and/or installer contact cylinder head. Measure dimension "L" (guide installed height). See Fig. 
16 or Fig. 15 . If installed height is not within specification, adjust or replace valve guide or cylinder head 
as necessary. See VALVE GUIDE INSTALLED HEIGHT . 

NOTE:

On Miata, use only NEW exhaust valve guides to replace intake or exhaust valve 
guides.

 

1997 Mazda MX-5 Miata 

1997-98 ENGINES 1.8L 4-Cylinder

  

VALVE GUIDE INSTALLED HEIGHT 

Fig. 16: Adjusting Valve Guide Installer & Installing Guide 
Courtesy of MAZDA MOTORS CORP. 

Application

In. (mm)

Miata & Protege

.720-.744 (18.30-18.90)

 

1997 Mazda MX-5 Miata 

1997-98 ENGINES 1.8L 4-Cylinder

  

Fig. 17: Measuring Installed Valve & Guide Height 
Courtesy of MAZDA MOTORS CORP. 

Valve Seat 

1. Service valve guide before valve seat. Valve seat replacement information is not available from 

manufacturer. Inspect valve seat for roughness and damage. Check valve seat angle and seat width.  

2. Measure seat contact width on valve and ensure seat contact position is in center of valve face. Service 

seat if angle and width are not within specification. See CYLINDER HEAD under ENGINE 
SPECIFICATIONS. Measure valve installed height after servicing valve seat. See Fig. 17 . See VALVE 
INSTALLED HEIGHT .  

3. If valve installed height is within serviceable range, install adjusting shim on spring seat. If installed 

height exceeds serviceable range, replace cylinder head.  

VALVE INSTALLED HEIGHT 

Application

In. (mm)

Miata & Protege

 

1997 Mazda MX-5 Miata 

1997-98 ENGINES 1.8L 4-Cylinder