20511110 Volvo.Penta Screw

R1S.C.6. Compressor
Introduction
The S.C.6 compressor is a single cylinder unit which is bracket supported from the cylinder block, the compressor being flange mounted to the rear of the compressor drive housing. This compressor drive housing is mounted on the rear of the timing case and incorporates a geared drive from the engine idler gear to compressor.The compressor draws air through the engine induction system. The air is then compressed and fed to the air reservoir. The compressor cylinder head incorporates an unloader device which is operated by air pressure and controlled by a governor valve connected to the reservoir and the compressor by a small bore pipe.Preventive Maintenance
Every 4 Months or Every 5,000 Miles (7,500 km)
Make a visual check of all joints, unions, etc., for leakage or looseness and rectify where necessary. If the cylinder head has recently been removed, check that the cylinder head nuts are fully tightened down to a torque of 10 lbf ft (1,38 kgf m) -13 Nm.Check compressor mounting and couplings for alignment.Clean air filter.Every 10,000 Miles (15,000 km) or 500 Hours
Clean the oil supply line to the compressor.Remove delivery valve cap and delivery valve seat retaining spring and check for presence of excessive carbon. Withdraw and check condition of delivery valve. If excessive carbon is found, remove and clean the cylinder head; also check compressor discharge line for carbon and clean or replace the line if necessary.Every 60,000 Miles (90,000 km) or 2,500 Hours
Dismantle compressor, thoroughly clean all parts and inspect for wear and damage. Repair or replace all worn or damaged parts or replace the compressor with a Factory Reconditioned Unit.Service Check Inspection
Ensure that the air cleaner or filter is clean and correctly installed.With compressor running, check for noisy operation and oil leaks.Reduce the pressure in the reservoir by operating the brakes and check that governor and unloader mechanisms are functioning at correct pressure. (If possible the vehicle gauge should be replaced during the test by a master gauge).Check to be sure compressor mounting bolts are secure.Operating Tests
If leakage in the remainder of the system is not excessive, failure of the compressor to maintain the normal air pressure in the system usually denotes loss of efficiency due to wear. Another sign of wear is excessive oil passing through to the reservoir. If either condition develops, and inspection shows the remainder of the air brake equipment to be in good condition, the compressor must be overhauled or replaced with a Factory Reconditioned Unit.Air Leakage Test
Excessive leakage past the delivery valve can be detected by charging the air system to just below the governor cut-out setting, and then with the engine stopped, carefully listening at the compressor for the sound of escaping air. If this test is satisfactory, fully charge the system and again stop the engine. Check once more for audible leaks, which if present indicate leakage at the unloader plunger.Leakage at the delivery valve can be remedied by cleaning, lapping or replacing the valve and/or valve seat. Unloader plunger leakage can be remedied by replacing the plunger seal or valve plunger.To Remove Compressor
Release all air pressure from the system.Disconnect oil pipe and air pipes at the compressor.Remove the setscrews securing the compressor drive and cover to the compressor drive housing.Remove the compressor mounting bolts and remove compressor from engine.To Replace Compressor
Fit compressor to compressor drive housing and secure with setscrews.Replace bracket which supports compressor to cylinder block.Reconnect oil pipe and air pipes to compressor.Important
Clean the oil supply line to the compressor and run the engine for a few seconds to be sure the oil supply is flowing freely.Connect oil and/or air pipes, ensuring that the air cleaner or filter is clean and properly installed.Check after Installation
With the compressor running, check for noisy operation and oil and air leaks.Dismantling
Marking before dismantling
The compressor should have the following items marked to show the correct relationship prior to dismantling.1. Position of cylinder head in relation to cylinder and crankcase.2. Position of end-cover(s) in relation to crankcase.3. Position of crankshaft in relation to crankcase.Removing and Dismantling Cylinder Head and Cylinder
Remove the unloader cap and copper washer and withdraw the unloader plunger assembly and spring.Remove the delivery valve cap and copper washer, and remove delivery valve spring and seat retaining spring.Unscrew the four nuts and washers from cylinder head studs and lift off cylinder head. Remove the joint.Remove the delivery valve and screw out the valve seat.Withdraw inlet valve spring guide. (A simple extractor can be made from two 1/4 in U.N.F. bolts and a strip of metal formed to bridge the guide). Remove the inlet valve spring, inlet valve and valve seat.Withdraw cylinder and remove the joint.Removing and Dismantling Piston and Connecting Rod Assemblies
Remove the compressor mounting bracket and joint.Turn the crankshaft to B.D.C. position and release the tabs of the locking strap. Unscrew the two bolts and remove the connecting rod cap. Withdraw piston assembly and replace connecting rod cap.Remove the piston rings from the piston. If the piston is to be detached from the connecting rod, release one gudgeon pin retaining circlip and press the gudgeon pin from the piston and connecting rod.Removing Crankshaft
Remove compressor drive gear.Remove drive key from crankshaft.Unscrew the four setscrews or nuts together with washers securing the rear end-cover to crankcase. Withdraw the end-cover, plain bearing, thrust washer and joint.Unscrew the four setscrews or nuts securing the drive end-cover, and withdraw the end-cover complete with crankshaft and joint. Tap crankshaft with bearing from drive end-cover.Cleaning
Ensure that all carbon is removed from the cylinder head. Check that the air passages in the head and the oilways in the crankcase, where applicable, rear end-cover and crankshaft are clear and clean.Clean inlet and discharge valves, not damaged or worn excessively, by lapping them on a sheet of crocus cloth held on a flat surface.Inspection of Parts
Cylinder
Check cylinder bore for excessive wear, out-of-round or scoring. If scored or out-of-round more than 0.002 in (0,05 mm) or tapered more than 0.003 in (0,08 mm) cylinder should be rebored. The original cylinder bore is to the limits