Engine Lubrication System

Oil Circuit Diagrams

	Oil Circuit in a Cold Engine
	Oil Circuit at Operating Temperature

Oil Strainer

Removal

Remove and replace the Oil Strainer 1. Remove hex nuts from oil strainer cover. 2. Remove oil strainer cover. 3. Remove oil strainer and gaskets.

Install

1. Check oil suction tube for proper positioning.
2. Clean oil strainer and remove gasket remnants.
3. Use new gaskets on both sides of the oil strainer.
4. Insert oil strainer making sure that the orifice in the strainer has a close fit around the oil suction tube.
5. Remove gasket remnants from the oil strainer cover. Straighten the cover if it is warped or bent, otherwise a good oil seal cannot be expected.
6. Clean magnetic filtering element.
7. Do not over tighten the hex retaining nuts, especially when using thicker gaskets, since this may warp the cover.

Note:

Magnetic Oil Filter Crankcase Oil strainer Magnetic filter Oil suction tube Stud Oil strainer cover Disc Rivet Gasket

Pressure Relief Valve

General

Functional Description of the Bypass Valve:

	1 Oil gallery to oil cooler 2 Oil gallery from oil pump 3 Oil gallery to lubricating points by bypassing the oil cooler 4 Opening for counter-pressure oil line.
	When the engine is not running, the valve (plunger) closes the passage to the lubricating points. As soon as the engine begins to run, the oil pump sucks oil from the oil sump in the crankcase and forces it to the bypass valve. The bypass valve is then forced down, under the pressure of the oil, and opens the oil gallery to the lubricating points by bypassing the oil cooler.
	As soon as the oil pressure has built up, some of the oil flows through the counter-pressure line to the cavity under the valve plunger equally counteracting the pressure exerted by the oil from above, permitting the mechanical spring to expand and, thus, push the valve plunger up and close the oil gallery of the direct lubricating circuit. This forces the oil to flow through the oil cooler before it can reach the lubrication points within the engine.

Removal

	1. Remove cap screw with tool P 74.
	2. Withdraw spring and valve plunger; if plunger is stuck, it can be removed with an M 10 thread tap.

Installation

1. Inspect valve plunger and plunger bore in housing for traces of seizure (scratches, etc.). Carefully smoothen the surfaces, replace if necessary.
2. Check mechanical spring

   Pressure Relief Valve and Bypass Valve Spring
   Free length............  66 mm (2.6in)
   Wire diameter.........  1.4 mm (.055in)
   Tension at 49 mm(1.93in).....4.7 kp (10.3 lbs) +/- 7%
   

3. Install new gasket washer.
4. Insert the piston so that its hollow end faces towards the cap screw.
5. To prevent scratching the bore in the housing, make sure that the spring end does not ride in the plunger bore in housing.

Oil Cooler

Removal

1. Remove air blower housing (4 En). 2. Unscrew oil cooler retaining nuts with a box wrench. ..

3. Remove oil cooler and gaskets.

Installation

1. Check oil cooler for leaks and proper tightness of retaining nuts (test pressure is 10 atm-147 psi).
2. If oil cooler is leaking, check pressure relief valve.
3. Use new gaskets.

Oil Pump

Remove

Remove engine rear shield and intermediate shield between the air ducts. Remove crankshaft pulley. Remove crankshaft pulleys shield, Remove oil pump cover. Remove oil pump gears.

Installation

1. Inspect oil pump housing, especially gear seating areas, for wear. Wear within the housing will result in decreased oil pressure.
2. Inspect pump gears for wear. Gear flank clearance should be O.03 - O.O5 mm (.001 - .003in.). Axial play of gears in the housing, with gasket but without preload, is 0.035 - O.10 mm (.0014 - 0039in.). Wear limit 0.20 mm (. 0079in).
3. Check shaft of driven gear for firm seating in the housing.
4. Check sealing surface for oil pump cover (a t crankcase) for cleanliness.
5. Place a straight edge across the face of the pump gears. Using a feeler gauge, measure clearance between the cover mounting flange in housing and face of gears, which should be 0.06- 0.l28 mm (. 0024 - .0050in).
6. Use a new,- genuine gasket (0. 20mm = . OO8in) without applying gasket paste. Gasket thickness in excess of specification will result in decreased oil pressure.

Bypass Oil Filter Cartridge

Unscrew filter cover retaining bolt. Withdraw filter cover. Withdraw filter cartridge with a slight turn. Remove oil from filter housing (use a suction pump). Clean filter housing interior (do not use shredded rags). Insert new cartridge by turning it slightly. Insert new gasket into housing cover, properly position the cover on the housing. depress, and tighten securely. Check engine oil level. Allow engine to idle for a few moments. Check for oil leaks in filter housing body and oil line connections. Recheck engine oil level. Replenish engine oil to the top mark on the oil dipstick (use premium. grade HD oil).

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