Centurion engine removal.

So you've got a Cent. with a duff engine?

I'll outline the field method of engine change (as well as I can remember it), but be prepared for a long job. My best time for an engine swap with a 4 man team was 10 1/2hours. So let's get started.

What you will need

Procedure.

We will examine this in four area defined stages and the final lift. The stages are:-

1. Gearbox end.
2. Turret end.
3. Right hand side.
4. Left hand side.

So let us open the old girl up and get this engine out

1. Park the gun at 9 0'clock
2. ensure the battery master switch is off
3. Open the transmission covers
4. lift the radiators
5. lower the transmission covers back against the radiators
6. Lift the engine covers and pyramid – lay – them onto the transmission covers.
7. Fold the oil cooler back between the turret bins
8. Tie down the pyramid.It has been known to have an engine cover fall on a mechanic during the procedure
9. Drain the oil tank and cooling system into "suitable- containers.
10. Replace and rewire plugs.

Gear box end

.

Remove the rear footplates, the centre support rail and the footplate support brackets.

Remove the sheetmetal baffle plate between the fans.

Support the clutch on a block of wood and remove the nuts retaining the clutch seal carrier to the rear of the engine and withdraw the seal carrier.

It may be necessary to remove the bearing blocks from the clutch actuating fork to allow to seal carrier to slide sufficiently to the rear.

Disconnect the oil supply line from the engine to the throw out bearing.

Remove the fan belts.

Normally we would cut these but in the interest of economy pull the belt jockey pulleys off the belts and secure the now exposed shaft of the jockey pulley spring housings with snap lock pliers to keep the pulley's weight off the belt. — the tanks originally carried 2 "U" shaped clips to go over the exposed shaft.

Hand crank the engine, or lever the clutch around until the dowel in the pulley is in its lowest position.

Remove the nuts securing the belt pulleys to the engine and withdraw the pulleys.

The belts should be kept as separate sets.

In the Turret.

Remove the kidney plate.

Turn the fuel tank selector switch to off.

Disconnect the leads to the starter and remove the starter. Take care to retain the shims between starter and engine.

Remove the hoses between the water pump and the water rail.

Disconnect the fuel pump supply lines.

Disconnect the magneto drop leads from both magnetos and the booster coil lead from the "A" bank magneto.

Disconnect the leads to the tacho and the Ki-gas piping.

Disconnect the thermometer and oil pressure sender units.

Remove the cover from the aux gen fan.

Remove the retaining nut from the fan spindle because the nut is also the hand cranking dog – It is left hand threaded.

Withdraw the fan and remove the circle of nuts which secure the fan shroud to the aux.gen.

Remove the fuel supply line between the electric pump and the Aux Gen carburettor.

Disconnect the leads from the side of the Aux Gen dynamomotor/alternator and mark them for correct replacement.

Remove the bolt holding the oil drain pipe from its bracket.

Disconnect aux.gen water supply piping at hose connection above the water pump.

Remove the fuel supply line between the electric pump and the Aux Gen carburettor.

Disconnect the leads from the side of the Aux Gen dynamomotor/alternator and mark them for correct replacement.

Remove the bolt holding the oil drain pipe from its bracket.

Disconnect aux.gen water supply piping at hose connection above the water pump.

R.H. Side of engine – "B" bank.

Remove the air cleaner completely — element, body and ducting to the engine.

While you are at it, hop over the engine and remove the other one too.

(Back to RHS.)

Remove the exhaust pipe between the engine and the hull wall.

Exhaust pipes have a spherical ring at engine end, and it, and manifold sections are sealed using piston ring type seals. Care in separating is advised.

Remove the heat shields form the manifolds and remove the manifolds.

Remove the small water (cylinder drain) hose between the engine and the water rail.

Remove the nuts from the engine hold down bolts.

Disconnect the oil supply and return pipes

Remove the oil tank

Open the Inspection cover to check for contaminants.

Disconnect throttle and choke connections.

Locate and remove the flame detector harness.

Disconnect the lines from the oil cooler.

Remove the oil cooler and remove its support bracket from above the R.H fan housing.

Remove the oil filter, plug all openings.

Disconnect the two hoses connecting the engine to the header tank.

L.H. Side of engine – "A" bank.

Disconnect the choke and throttle control cables from the Aux. Gen.

Disconnect the lower water connection between the Aux. Gen. and the main engine.

Disconnect the upper water connection.

Remove the exhaust pipes from both the main engine and the Aux.Gen.

Disconnect the air trunking between main engine and Aux.Gen.

Locate and disconnect the sleeve in the low tension wiring to the distributor.

Beware, there is a small tension spring and an insulator sleeve in the sleeve housing which could be dropped.

Remove the two nuts on the support bolts.

Fit a two legged sling to diametrically opposed cylinder head bolts toward the rear end of the Aux.Gen.engine. Take the weight and wriggle the Aux.Gen toward the transmission compartment. When the dynamo section of the unit is sufficiently clear lift the assembly clear of the hull.

It is possibly for either the oil drain tube or the lower water connection to foul during this step. Although I've never done it, a rope cradle would probably suffice to remove the unit although balance would be difficult to achieve.

While the assembly is out consider separating the engine and dynamo so that the condition of the anti vibration insulator bushes can be checked.

Remove the exhaust shields and manifold from the engine.

Disconnect the bleed hose between the water rail and the engine.

Remove the engine hold down nuts.

If I've remembered everything, your engine is ready to lift.

While the workshop type main engine lifting sling is an out–of–solid shape "T" frame with 3 dangling legs, the early engines had lugs fore and aft of the engine on both sides so a 4 legged sling of sufficient length (and strength) will suffice. As it will become necessary to tilt the engine slightly during the lift some means of inducing the tilt (perhaps a simple twitch) would be helpful. If a four leg sling is used take care not to crush the exhaust plug leads.

The Lift.

Take up the slack in the lifting gear.

Ensure that the hold down bolts have dropped clear of the engine (don't worry, they can't get lost).

Lift slightly; slide the engine toward the turret.

Make a final check that nothing is fouling and hoist till the engine is clear of the water rails.

Turn the engine so that the gear box end moves toward the B bank fuel tank and continue lifting. It is about this time that the need to tilt becomes necessary.

I'm inclined to think the gear box end needs to be lower than the starter end but memory, or lack of, fails me. There isn't a lot of room to play with but the engine should come clear of the hull.

While the engine is out, take the opportunity to clear the gunk and dropped tools from the hull.

Putting it back together?

Just reverse the process, taking special care when refitting the engine/clutch shaft seal. Check that you have replaced split pins/wire wherever they/it was removed.

Caution: Exercise care in the removal of nuts and studs. This is an aluminum casting, Studs and bolts are of smaller diameters than usual. Care in the amount of tension used is critical. The brute force and ignorance method is not recommended.