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