How to Approach an Engine Rebuild
Ever wondered where to even begin with rebuilding the tired old engine in your Series 1? I have. There are plenty of self-help books on the topic but, none of these really give any help with diagnostics. I turned to Ian Cox who is part owner of one of the best workshops in the industry. he kindly put his thoughts to paper. Below is his advice on rebuilding a 1956 2L.
"O.K. - For 1956 you should have a "late 2 litre" unit. This means you will
have a full flow oil filter and a rear crank oil seal. Your block will have
water between all the cylinders and depending on exact date should have thelarger 7/8" gudgeon pins and threaded flywheel with removeable ring gear.
All of this makes for the best of all the Series one engines - so far so
good. The first thing with any rebuild is to see what you've got. It's
pointless for example taking off the head and rebuilding it only to discover much later that the block is cracked. Start by stripping the unit down to its bones. If you are not used to engine rebuilds then it is a good idea to keep all the parts from particular bits of the engine separate and
labelled - plastic ice cream tubs are good for this. Be aware of the
general condition of things as you go. Too many people tear things apart
and destroy the evidence of problems which then go unnoticed and come back to haunt them later. Examples are - evidence of water/oil leaks, signs of overheating, evidence of water or dirt in the oil. I normally discard any non-Land Rover parts (odd bolts, star washers, etc) at this stage because I know what should be where. If you are less confident then keep everything and discard the rogues on reassembly.
Once the unit is stripped and given an initial clean then its condition can
be assessed. Start with the obvious and serious stuff - cracks. Late 2
litres are not bad for cracks but check for a curved crack underneath the
front core plug or a straight one along the water jacket "ridge" again under the front core plug. Less common but more serious are cracks in the valve chest behind the camshaft - check for signs of water in the oil.
Check also the cylinder bores, especially number 4, for a straight crack coming from the bottom of the exhaust valve seat and extending down the bore. Heads very rarely crack but have a look on the face anyway.
Having done all this you can look at wear. It is a common misconception
that if for example the bores are slightly worn then this can be attended to and the rest of the unit will be O.K. These engines are quite well matched and all the components wear at about the same rate (with the exception of the cam and followers - more later). If the block has ridges in the bores you can catch a finger nail on then it is a safe bet that the crank will need grinding and the valve guides will need replacing and the cam will be worn out, etc, etc, etc. Check over all the major components and get a "feel" for how worn the engine is. Most of this checking can be visual (such as timing sprockets) or done by feel (such as valves and guides) but the bores and the crank journals should be measured. This will tell you if anyone else has had a go at the engine before you and will assist in getting the right size parts.
Bearings for the late 2 litre are available in all sizes up to 0.060".
Pistons are also available up to 0.060" but large sizes are more expensive.
Cylinder liners are available for very worn or damaged bores.
Now is the time when you must decide what sort of unit you want to end up
with after your rebuild, or to put it another way, what your budget is.
Pretty much every part is available for these engines from us and many parts from other suppliers also so it really comes down to balancing cost against end result. A fully rebuilt unit ready to fit into the vehicle will cost £2500 from us, about £1200 of that is parts, the rest is machining work, cleaning and assembly. It is often possible for the DIY rebuilder to
produce a reasonable engine for around £1000 providing the base unit wasn't too bad.
If you are going to do your rebuild in stages then now is the time to oil up
all the bits you are not going to need for a while and put them away
somewhere safe.
The stages I would suggest are:
1) Block, crank, pistons & rods.
2) Exh valves, cam & followers, timingchain & sprockets, timing cover.
3) Oil pump, sump, flywheel & housing, front pulley, oil filter & housing. 4) Cylinder head.
5) All extra bits (manifolds, carb, dynamo, starter, clutch, etc).
Overall: Use new circlips, lock tabs, split pins, gaskets and seals
throughout the engine without exception.
Stage 1)
You will need to decide on a rebore (recommended) or just a hone and
re-ring. Bores are always worse than they look because they do not wear
equally all the way round. It is normal for one of these engines to require
0.030" bored out to clean up. If a bore is damaged or there is excessive
wear then liners can be fitted to return to standardbore size. Exhaust
valve seats have a habit of cracking - if they are cracked then replace them. The original seats will cope with unleaded fuel if they are in good condition and the vehicle is not driven hard for long periods. If the valve guides are worn then replace them also and deffinitely if the seats are to be replaced. Remove the 4 large core plugs, flush the block out thoroughly and fit new core plugs.
The block can be refaced if the face is damaged or distorted. The crank
should be reground unless it is really good - even small marks will reduce
the life of new bearings dramatically. Normally less material needs to be
removed from cranks than you might think. A crank has to be really bad not to clean up with a 0.010" grind. The 7/8" small ends do not wear badly and as long as a new gudgeon pin is not slack in the bushes then they can be left alone. To cut the cost down it is sometimes possible to use a good second hand set of oversize pistons and bore the block to suit using new rings, pins & circlips. Always fit a new rear crank oil seal and fill it
with high temp grease as per the manual.
Stage 2)
The cam and followers on these engines are their weak point and it is very
likely that all these components are in bad shape. All the parts are
available but are not cheap. As long as the cam lobes are not badly worn
then the cam can be reprofiled and reused but the followers must be
carefully inspected. The followers are hard chrome faced and that has a
habit of wearing through, leaving a sharp edge of chrome pushing against the camshaft and machining it away. Check the faces of the followers in a
strong light. If there is a dark line visible across the face of the pad
then the follower should be replaced. Note: followers must not be refaced in the same way as rocker arms - this removes the chrome coating and they last about 2 minutes!!! The follower shaft wear badly also and these should be replaced. The cam bearings can normally be re-used provided they have not picked-up on the cam. New exhaust valves are a good idea but a good set of second hand ones may be refaced at a pinch. Valve springs are normally fine to reuse. Fit a new timing chain. Check the tensioner assembly - wear here will reduce oil pressure. You will need to temporarily fit the flywheel housing and flywheel in order to set the valve timing.
Stage 3)
The oil pumps do not normally give much trouble on these engines. They are a gear type pump and as with all gear pumps the maximum leakage actually occurs around the end of the gears. I normally strip the pumps for cleaning and reface the upper part of the body (the large flat face on top of the gears) - this can be done in a good lathe. The gears should be inspected and if damaged should be replaced. New gears are like hens teeth but good second hand pumps are easily found. The bush in the Alu gear can be replaced if badly worn as can the spindle post but this is not normally necessary. If the strainer is damaged then fit a new one - they are available and cheap.
Early type flywheels have integral teeth and these are normally badly worn. The only option there is to machine the teeth off and fit a shrunk-on
replacement gear. Later flywheels have shrunk-on gears from new but
ironically these hardly ever wear and should not need replacing. If the
clutch surface is grooved or has surface cracks and signs of overheating
then it should be refaced, otherwise a good rub with some medium emery will suffice.
Be sure to use the correct bolts and lockwashers when reassembling the oil
pump, flywheel & housing. Fit a new pressure relief valve ball also and a
spring too if it shown signs of wear.
Stage 4)
Cylinder heads give very little trouble on these engines. All that is
usually required is a good clean-up, cut the valve seats, face the valves
and reassemble. Do check the fit of the valves in the guides however and if there is wear then the guides should be replaced. Be sure to correctly fit new valve stem seals and note that once the valves have been installed in them they cannot be removed without wrecking the seals. Reface the head if the face is damaged or distorted, otherwise just clean up.
The rocker shaft assy should be stripped and cleaned. The rockers will
probably need refacing and the shaft will probably need renewing although the rocker bushes do not suffer badly and can normally run again. The pushrods should be inspected for the formation of "nipples" on the rounded end - these can be carefully ground off but a new set of pushrods is cheap and probably a better bet.
Reassemble all parts with the correct fasteners and lockplates etc. Make
sure all head bolts are in good condition and tighten to the correct torque,
including the two long studs that hold the rocker shaft also. Fit a new
thermostat as a matter of course and check the water pump for any signs of roughness in the bearings or leaks from the drain hole underneath. The
choke light sender plate may well be badly corroded - we have new ones but you will need to rejuvenate your old switch unit. These are simple and once carefully stripped and cleaned they normally work just fine.
Stage 5)
This is what we refer to as ancilliaries. Inlet manifolds give no trouble,
neither do the front pulley/damper units so clean and refit both. Engine
mount brackets can be refitted with the correct lock tabs and new mounting rubbers should be used. If the water pump shown signs of leakageor roughness then fit a new one now - it is a lot more difficult in the vehicle. New radiator hoses are a good idea for the same reason, also a new fan belt. Early type "flat" fans have a habit of cracking where the blades cross over one another. Check this since losing a blade is a frightening and dangerous experience.
It is a good idea to fit a reconditioned carburettor at this stage (or
rebuild your own) since they have a habit of running rich and this causes
"fuel wash" in the top of the cylinder bores resulting in rapid bore and
piston ring wear - not good for a new engine. A badly worn distributor is
no good either, the spindle will move away rom the points causing a variable spark and erratic running. If in doubt fit a rebuilt unit. Starters and dynamos are easy to diagnose the condition of - they either work or they don't!
Exhaust manifolds have a habit of warping away from the block in the centre and ultimately cracking. They are also notoriously bad on the exhaust pipe studs. If yours is bad then reface and restud it or fit a reconditioned unit.
And that's about the lot! There is no great mystery surrounding these
engines provided you work methodically, follow good engineering practice and the workshop manual then a god job will result. We can sullp any and all the parts that you may need, together with reconditioned sub-assemblies (such as oil pumps and rocker shaft units) and reconditioned ancilliaries such as starters and carburettors.
Have fun and don't be afraid to ask if there is anything I can help with.
Regards
Ian M Cox
Cox & Turner Engineering
Engine Reassembly
In this photo gallery Ian Stuart has documented many of the steps in rebuilding a 2L motor. The web site is hosted outside of the Series One Garage. Click here to see it.
Important Announcement
