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Replacing Rear Crank Oil Seal On A 3 Bearing Diesel

Replacing Rear Crank Oil Seal On A 3 Bearing Diesel

If you have the facilities to remove the engine - then do, but you will still need to have access from underneath, so an engine stand is also required allowing access to the flywheel end.

For those ill equipped, or requiring the minimum of space, then this method may prove useful.

The 3 Bearing Diesel is awkward, as it requires the removal of the sump, and #1 crank bearing to give enough access to it.

Method

Remove bonnet, seats, footwell pans, gearbox tunnel and front cover, and seatbase. You may want to remove the LH sills too as this gives you a walk-in route and saves fatigue.
Make sure vehicle is well chocked and stable, then remove rear prop at the handbrake end, and front prop at the gearbox.

Drain oil from engine sump.

Using a jack and spreader (6x2 x2ft joist) take the weight of the gearbox, and undo the mounts to the X member.

Use several lifting slings over the roof of the vehicle, and at least a 500kg ratchet strap over a central lifting Eye. Passing the strap over the main gearbox and between the transfer box at the point nearest the joint is the equilibrium point.

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Lift enough to place a 1/2" chock under the flywheel housing and cross member. Adjust to rest weight of engine on this, then remove outer nuts to remove bellhousing. The gearbox unit may now be swung back, and if turned to towards you, may be rested on the exhaust to steady.

Gearbox input oil seal replacement

Any smell of EP90 in there will indicate a damaged seal, as will seepage from the release bearing area. It is now straightforward to remove the bolt from the clutch fork, and remove the clip that secures it.

Undo the nuts and bolts securing the housing, and remove it.

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The simplest way to remove this seal is to drill into the corner of the seal, then use a self tapping screw to jack it out.

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Clean all fixings in white spirit, and allow to dry. Clean fixing holes and dry. After cleaning the housing, use a smear of hymolar around the new seal, and drift in with a small piece of wood to protect it. Remember this time groove of seal is visible. Grease seal lips and input shaft slope, and the new gasket, and assemble using threadlock on fixings.

Rear crank oil seal

Start by removing the clutch cylinder and starter, then remove the 6 clutch securing bolts. Remember to loosen them only 1 turn at a time to prevent distortion. The clutch disc will then fall out when the spring plate is removed. Inspect clutch parts, and order a new friction disc and clutch bearing if other components are fine. The clutch bolts can be awkward, but impact driver may prove useful to start

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Jam the flywheel, and undo the 8 centre bolts. Removal is then possible, It's very heavy, so use 2 of the clutch bolts at 9 and 3 o'cklock as a handle- and watch your back.

Make sure the front engine mounts are in good condition as this method is dangerous if they are not. Use a sling/ rope around the rear engine lift point, and place a heavy beam at the bulkhead to support it. As an additional safety measure, a piece of 3x2 the width of the bulkhead bay, can be wedged behind the engine as it is jacked up from below.(use spreader to prevent damage to sump) Chocks from above prevent the engine tipping back. When you are certain it cannot move, lower the jack to test.

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If all is safe, use jack again as safety, and remove all sump bolts - and the central back nut. Split off the sump, and lower it on the jack. Stuff with newspaper , and scrape off old gasket.

Using a breaker bar, slacken off the two large bolts near the seal end.

From inside again, remove the flywheel housing bolts - remember 2 are outside the casting, and a bit of manouvering may be needed. Support engine on jack and beam as needed. Remove this housing and clean all the gunk out.

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The seal housing can now be seen, but you will need to put 4 bolts back on the crank to turn it. Use a ring spanner for this (and gloves) rotate to access all the bolts. Remove them all with a 1/4 drive socket.

Prise off the top of the seal housing, taking care not to damage the rubber coating on the diameter or the rear. These are on pins- so will slide forward as a unit before coming apart. Don't expect the bottom one to come out - just remove the top.

From underneath, undo the 2 large bolts, and drop the bearing cap/ end with seal housing attatched. This may be stiff, but can be twisted to help.

The seal is now visible - give it a clean with spray cleaner. Using a screwdriver or spring hook, try to remove the spring out of the rear of the seal - pull it out with pliars. The seal should now split easily and come off. Clean again with spray cleaner, and wipe dry. Clean journal block and all parts, bolts etc.

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Take a break. (fiddly bit coming up)

Familiarise yourself with how the new spring goes together. From underneath again, pass the straight spring around the shaft and hook together without stretching it AT ALL. This is just possible if you press one end against the flange face, and push the other end onto it.

This is the hardest bit - take your time. Enjoy success.

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Grease the new (soft) seal with silicone grease, and open it out slowly to about 1". With the spring on the engine side, push the seal over the shaft from underneath - grooved side towards engine.

With the spring join at one side, press the spring join into the seal groove, then chase it around with a pair of blunt spanners. From above, finish off this, and ensure all looks well.

Reassembly

Clean the outside of the seal, and faces of parts. Grease new cork T seals on the block, and press them in. There should be a generous amount at the bottom. Oil bearing shell, and, using 2 feeler gauges, press this block into position - Remember to attach the bottom seal housing first, smeared with hymolar at the face with the block - and in the seal groove. Just position bolts with fingers to maintain position Stop when 1/4" away from home.

Check with a mirror that the seal is exactly square, and sitting in the groove it should be in. The seal housing should be 1/8" away from the block at this stage.

Continue tightening the bottom bolts - and check position again from above. When fully home, position top seal retainer over seal, then remove- checking the hymolar for contact points. If it looks pointy - all is well. re-attach, and press so that the seal housing meets.

Check with mirror again.

Torque the 2 bearing bolts to spec underneath.

Use a clamp on the housing to squeeze it together, while you press it over the pins in the block with a lever against the crank.

Once this is done, use treadlock on the housing bolts, and insert them as you rotate the crank. Do this progressively (remove clamp) to avoid distortion at the joins. Check seal is ok, then tighten fully.

Use a new O ring in the flywheel housing, and use grease as a jointing paste (mine had no paper gasket Sealing this serves no purpose I can see.)

Secure all bolts with threadlock, and torque to spec.

Replace flywheel, and torque bolts - use locktabs for these.

Trim the cork seals using a washer as a guide to leave 0.030" proud.

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Use a new sump gasket, use silicone rtv on both sides, and refit the sump.
Do not overtighten sump bolts.

Clutch

Fit a new friction disc at the minimum, and a new release bearing. Centralise with suitabe stick - make sure "Flywheel side" is that, and replace spring plate - progressively tightening the 6 bolts. Secure these with threadlock.

Support engine on spreader board and jack, and remove additional supports.

Rejoin gearbox to engine - rotating crank if needed. Make sure bellhousing studs are set, and use nuts to tighten. Do not use studs with nuts attatched.

Reseat on mountings, and bolt up.

Replace items removed initially (starter, slave cydr), and don't forget clean engine oil!

Clear away and double check for loose items.
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