Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSSUBARU1998FORESTER AWD F4-2.5L DOHCREPAIR AND DIAGNOSISSPECIFICATIONSMECHANICAL SPECIFICATIONSENGINECYLINDER BLOCK ASSEMBLYSYSTEM SPECIFICATIONSSERVICE SPECIFICATIONS
1998 Subaru Forester AWD F4-2.5L DOHC
Service Specifications
1998 Subaru Forester AWD F4-2.5L DOHCSECTION Service Specifications
Bore x Stroke 99.5 x 79.0 mm (3.917 x 3.110 inch)
Displacement 2,457 cm3 (149.93 cubic inch)
Compression Ratio 9.5
Surface Warpage Limit:
Mating With Cylinder Head 0.05 mm (0.0020 inch)
Surface Grinding Limit 0.1 mm (0.004 inch)
Cylinder Bore:
Standard:
A 99.505 - 99.515 mm (3.9175 - 3.9179 inch)
B 99.495 - 99.505 mm (3.9171 - 3.9175 inch)
Taper:
Standard 0.015 mm (0.0006 inch)
Limit 0.050 mm (0.0020 inch)
Out-Of-Roundness:
Standard 0.010 mm (0.0004 inch)
Limit 0.050 mm (0.0020 inch)
Piston Clearance:
Standard 0.010 - 0.030 mm (0.0004 - 0.0012 inch)
Limit 0.050 mm (0.0020 inch)
Enlarging (Boring) Limit 0.5 mm (0.020 inch)
Displacement 2,457 cm3 (149.93 cubic inch)
Compression Ratio 9.5
Surface Warpage Limit:
Mating With Cylinder Head 0.05 mm (0.0020 inch)
Surface Grinding Limit 0.1 mm (0.004 inch)
Cylinder Bore:
Standard:
A 99.505 - 99.515 mm (3.9175 - 3.9179 inch)
B 99.495 - 99.505 mm (3.9171 - 3.9175 inch)
Taper:
Standard 0.015 mm (0.0006 inch)
Limit 0.050 mm (0.0020 inch)
Out-Of-Roundness:
Standard 0.010 mm (0.0004 inch)
Limit 0.050 mm (0.0020 inch)
Piston Clearance:
Standard 0.010 - 0.030 mm (0.0004 - 0.0012 inch)
Limit 0.050 mm (0.0020 inch)
Enlarging (Boring) Limit 0.5 mm (0.020 inch)
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.