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.

SYS.OK|MANUAL.DB● LIVE

HOMESERVICE MANUALSSUBARU2005OUTBACK I, STANDARDREPAIR AND DIAGNOSISENGINE MECHANICALTIMING BELTENGINE MECHANICAL (H4SO)GENERAL DESCRIPTIONSPECIFICATION

2005 Subaru Outback i, Standard

Engine Mechanical (H4SO): General Description: Specification

2005 Subaru Outback i, StandardSECTION Specification

ENGINE SPECIFICATION

Engine

Model

2.5 L NA

Cylinder arrangement

Horizontally opposed, liquid cooled, 4-cylinder, 4-stroke gasoline engine

Valve system mechanism

Belt driven, single over-head camshaft, 4-valve/cylinder

Bore x Stroke

mm (in)

99.5 x 79.0(3.917 x 3.110)

Displacement

cm³ (cu in)

2,457(150)

Compression ratio

10.0

Compression pressure (at 350 rpm)

kPa (kg/cm² , psi)

1,020 - 1,275 (10.4 - 13.0, 148 - 185)

Number of piston rings

Pressure ring: 2, Oil ring: 1

Intake valve timing

Open

BTDC 2°⁽¹⁾
BTDC1°

ABDC 56°
⁽¹⁾ABDC 51°

Exhaust valve timing

Open

BBDC 40°
⁽¹⁾BBDC 50°

ATDC 8°

Valve clearance mm (in)

Intake

0.20+/-0.04 (0.0079+/-0.0016)

Exhaust

0.25+/-0.04 (0.0098+/-0.0016)

Idle speed [at neutral position on MT, or "P" or "N" range on AT]

rpm

650+/-100(No load)
800+/-100 (A/CON)

Ignition order

1-->3-->2-->4

Ignition timing

BTDC/rpm

13°+/-10°/650

⁽¹⁾

U5 model

NOTE: US: undersize OS: oversize

US: UNDERSIZE OS: OVERSIZE REFERENCE

Belt tension adjuster	Protrusion of adjuster rod			mm (in)	5.2 - 6.2 (0.205 - 0.244)
Belt tensioner	Spacer O.D.			mm (in)	17.955 - 17.975 (0.7069 - 0.7077)
	Tensioner bushing I.D.			mm (in)	18.00 - 18.08 (0.7087 - 0.7118)
	Clearance between spacer and bushing		mm (in)	Standard	0.025 - 0.125 (0.0010 - 0.0049)
	Side clearance of spacer		mm (in)	Standard	0.20 - 0.55 (0.0079 - 0.0217)
Valve rocker arm	Clearance between shaft and arm		mm (in)	Standard	0.020 - 0.054 (0.0008 - 0.0021)
Camshaft	Bend limit			mm (in)	0.020 (0.00079)
	Side clearance		mm (in)	Standard	0.030 - 0.090 (0.0012 - 0.0035)
	Cam lobe height mm (in)	U5 model	Intake	Standard	39.485 - 39.585 (1.5545 - 1.5585)
			Exhaust	Standard	39.843 - 39.943 (1.5686 - 1.5726)
		Except for U5 model	Intake	Standard	39.485 - 39.585 (1.5545 - 1.5585)
			Exhaust	Standard	39.720 - 39.820 (1.5638 - 1.5677)
	Camshaft journal O.D.			mm (in)	31.928 - 31.945 (1.2570 - 1.2577)
	Camshaft journal hole I.D.			mm (in)	32.000 - 32.018 (1.2598 - 1.2605)
	Oil clearance		mm (in)	Standard	0.055 - 0.090 (0.0022 - 0.0035)
Cylinder Head	Surface warpage limit (mating with cylinder block)			mm (in)	0.03(0.001)
	Grinding limit			mm (in)	0.1 (0.004)
	Standard height			mm (in)	97.5 (3.84)
Valve seat	Refacing angle				90°
	Contacting width	mm (in)	Intake	Standard	0.8 - 1.4(0.03 - 0.055)
			Exhaust	Standard	1.2 - 1.8(0.047 - 0.071)
Valve guide	Inside diameter			mm (in)	6.000 - 6.012 (0.2362 - 0.2367)
	Protrusion above head		mm (in)	Intake	20.0 - 21.0 (0.787 - 0.827)
				Exhaust	16.5-17.5 (0.650 - 0.689)
Value	Head edge thickness	mm (in)	Intake	Standard	0.8-1.2(0.03 - 0.047)
			Exhaust	Standard	1.0-1.4(0.039 - 0.055)
	Stem outer diameters		mm (in)	Intake	5.950 - 5.965 (0.2343 - 0.2348)
				Exhaust	5.945 - 5.960 (0.2341 - 0.2346)
	Valve stem gap	mm (in)	Standard	Intake	0.035 - 0.062 (0.0014 - 0.0024)
				Exhaust	0.040 - 0.067 (0.0016 - 0.0026)
	Overall length		mm (in)	Intake	120.6(4.75)
				Exhaust	121.7(4.79)
Value spring	Free length			mm (in)	54.30(2.1378)
	Squareness				2.5°, 2.4 mm (0.094 in)
	Tension/spring height		N (kgf, lb)/mm (in)	Set	214 - 246 (22 - 25, 48 - 55)/ 45.0 (1.772)
				Lift	526 - 582 (54 - 59, 119 - 130)/ 34.7 (1.366)
Cylinder block	Surface warpage limit (mating with cylinder head)			mm (in)	0.025 (0.00098)
	Grinding limit			mm (in)	0.1 (0.004)
	Standard height			mm (in)	201.0 (7.91)
	Cylinder inner diameter	mm (in)	Standard	A	99.505 - 99.515 (3.9175 - 3.9179)
				B	99.495 - 99.505 (3.9171 - 3.9175)
	Taper		mm (in)	Standard	0.015(0.0006)
	Out-of-roundness		mm (in)	Standard	0.010(0.0004)
	Piston clearance		mm (in)	Standard	-0.010 - 0.010 (-0.00039 - 0.00039)
Piston	Outer diameter	mm (in)	Standard	A	99.505 - 99.515 (3.9175 - 3.9179)
				B	99.495 - 99.505 (3.9171 - 3.9175)
			0.25 (0.0098) OS		99.745 - 99.765 (3.9270 - 3.9278)
			0.50 (0.0197) OS		99.995 - 100.015 (3.9368 - 3.9376)
	Piston pin standard diameter			mm (in)	23.000 - 23.006 (0.9055 - 0.9057)
Piston pin	Outer diameter			mm (in)	22.994 - 23.000 (0.9053 - 0.9055)
	Standard clearance between piston and piston pin			mm (in)	0.004 - 0.008 (0.0002 - 0.0003)
	Degree of fit				Piston pin must be fitted into position with thumb at 20°C (68°F).
Piston Ring	Ring closed gap	mm (in)	Top ring	Standard	0.20 - 0.35 (0.0079 - 0.0138)
			Second ring	Standard	0.37 - 0.52 (0.0144 - 0.0203)
			Oil ring	Standard	0.20 - 0.50 (0.0079 - 0.0197)
	Ring groove gap	mm (in)	Top ring	Standard	0.040 - 0.080 (0.0016 - 0.0031)
			Second ring	Standard	0.030 - 0.070 (0.0012 - 0.0028)
Connecting Rod	Bend twist per 100 mm (3.94 in) in length	mm (in)	Limit		0.10(0.0039)
	Side clearance of large end	mm (in)	Standard		0.070 - 0.330 (0.0028 - 0.0130)
Bearing of large end	Oil clearance	mm (in)	Standard		0.016 - 0.044 (0.00063 - 0.0017)
	Bearing size (Thickness at center)	mm (in)	Standard		1.492 - 1.501 (0.0587 - 0.0591)
			0.03(0.0012) US		1.510 - 1.513 (0.0594 - 0.0596)
			0.05 (0.0020) US		1.520 - 1.523 (0.0598 - 0.0600)
			0.25 (0.0098) US		1.620 - 1.623 (0.0638 - 0.0639)
Bush of small end	Clearance between piston pin and bushing	mm (in)	Standard		0 - 0.022 (0 - 0.0009)
Crankshaft	Bend limit			mm (in)	0.035(0.0014)
	Crank pin	Out-of-roundness		mm (in)	0.003(0.0001)
		Cylindricality		mm (in)	0.004 (0.0002)
		Grinding limit (dia.)		mm (in)	To 51.750 (2.0374)
	Crank journal	Out-of-roundness		mm (in)	0.005 (0.0002)
		Cylindricality		mm (in)	0.006 (0.0002)
		Grinding limit (dia.)		mm (in)	To 59.750 (2.3524)
	Crank pin outer diameter	mm (in)	Standard		51.984 - 52.000 (2.0466 - 2.0472)
			0.03(0.0012) US		51.954 - 51.970 (2.0454 - 2.0461)
			0.05 (0.0020) US		51.934 - 51.950 (2.0446 - 2.0453)
			0.25 (0.0098) US		51.734 - 51.750 (2.0368 - 2.0374)
	Crank journal outer diameter	mm (in)	Standard		59.992 - 60.008 (2.3619 - 2.3625)
			0.03(0.0012) US		59.962 - 59.978 (2.3607 - 2.3613)
			0.05 (0.0020) US		59.942 - 59.958 (2.3599 - 2.3605)
			0.25 (0.0098) US		59.742 - 59.758 (2.3520 - 2.3527)
	Side clearance	mm (in)	Standard		0.030 - 0.115 (0.0012 - 0.0045)
	Oil clearance	mm (in)	Standard		0.010 - 0.030 (0.0004 - 0.0012)
Main bearing	Main bearing mm (in)	#1, #3	Standard		1.998 - 2.011 (0.0787 - 0.0792)
			0.03(0.0012) US		2.017 - 2.020 (0.0794 - 0.0795)
			0.05 (0.0020) US		2.027 - 2.030 (0.0798 - 0.0799)
			0.25 (0.0098) Us		2.127 - 2.130 (0.0837 - 0.0839)
		#2, #4, #5	Standard		2.000 - 2.013 (0.0787 - 0.0793)
			0.03(0.0012) US		2.019 - 2.022 (0.0795 - 0.0796)
			0.05 (0.0020) US		2.029 - 2.032 (0.0799 - 0.0800)
			0.25 (0.0098) US		2.129 - 2.132 (0.0838 - 0.0839)

RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready Tools Free Quote Check Quote Shield Pro

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.