200TDi into Defender - some useful information
Guide for DIY fitting - by Glencoyne Engineering
Preparing your new engine
I always like to prepare the new engine as far as possible before removing the old one. This minimises the amount of time that the vehicle sits around immobile. Engine prep will probably take you the best part of a day.
First step is to strip off all the bits that you don't need or that get in the way. Remove any wiring (apart from the glow plug wires), coolant hoses, oil cooler pipes etc. Remove the viscous fan - ideally while the fan belt is still in place. Use a 32mm viscous coupling spanner and give it a clout with a hammer (thread undoes clockwise from the front). These couplings are very tight and sometimes I have had to resort to a hammer and chisel to shock it free. Remove the starter, alternator, power steering pump and clutch. Now is a good time to clean the engine. If using a jetwash make sure you seal up all the places where water might get in.
If you are planning to change the timing belt, now is an ideal time. I always change the timing belt, tensioner, idler and front crank seal on every conversion I do. I have seen quite a few engines where the old timing belt is about ready to let go. Remember that an old Disco could have been run for the last few years of its life with very little maintenance. Click here for more information on timing belt replacement.
It is also worth removing the water pump housing and fitting a new 'P' gasket (the on between the housing and block) as these are a known weak spot on the 300TDi. Check the water pump carefully while it is off, as the impeller can work loose and fall off the shaft. if there is any sign of oil on the block below the manifolds, change the manifold gasket - almost certainly the old one will come off in two or three pieces.
Your next task is to prepare the flywheel housing so that it will mate with the gearbox. Much easier than a Disco 200 engine, you just need to drill and tap the blind hole at the very bottom to take an M10 stud, and remove a couple of the other studs. This can be done without removing the flywheel housing from the engine, but I would recommend that you remove the flywheel, check the rear crank oil seal and replace it if there is any evidence of oil leakage. Unlike the 200, the 300 seal comes with its own carrier which bolts to the block. You also need to grind a little metal off the outside of the housing to clear the clutch slave cylinder, and this is much easier to do if you remove the flywheel housing from the engine and offer it up to the gearbox.
Using the 300TDi flywheel housing on an LT77 gearbox is not absolutely ideal as you will find you are missing three engine to gearbox studs, and there is not enough metal in the casting to drill and tap it to take them. However, the missing studs are all in the bottom half of the housing: the position of the engine mounts makes a 300TDi installation nose-heavy, so the stress is on the upper studs which are all present. It doesn't worry me, especially as more modern engines only have four or five bolts attaching them to the gearbox, rather than the fourteen that the LT77 was designed with.
Unlike the 200TDi there is no need to 'clock' the turbo housing, but the pipe from the back of the housing to the injection pump will foul the bulkhead. Use a 6mm T connector in the hose between the turbo and actuator, and blank the original connection with a short self-tapping bolt. Job done.
Now you have done as much prep work as you can on the new engine it is time to remove the old one. You will need to remove the bonnet and radiator. Front panel will also need to come out unless you have a crane big enough to lift the engine over it. Also the exhaust front section (or the whole exhaust unless you are converting a 2.5TD and plan to retain the original exhaust). Inside - transmission tunnel, passenger side floor panel, remove the screws on the diaphragm panel (between the transmission tunnel and bulkhead) then remove enough screws on the drivers side floor panel to be able to jiggle the diaphragm panel out from underneath it. You don't need to remove the drivers side floor panel unless the footwell is rotten and you want to weld it up. Disconnect the engine wiring loom at the bulkhead (multipin connector), disconnect the battery lead from the starter and earth strap between chassis and engine block and you can take the engine out with the loom still attached. Remove the air filter housing and bracket (three M6 bolts, one of which is almost impossible to reach). Disconnect throttle cable, servo pipe, fuel lines, power steering pipes (if fitted), glowplug cable (on diesels) and anything else that needs to come off. Remove all the bellhousing nuts and the top and bottom nuts on the engine mounts, lift the engine far enough up to remove the rubber mounts, then lower it slightly, support the front of the gearbox (tall jack, or thick block of wood between gearbox and crossmember) and the engine should pull out.
Wiring loom - it is helpful to fit this to the new engine before you drop it into the vehicle. In particular the starter solenoid wire (red/white) is very difficult to get to with the engine in the vehicle. Your old wiring loom should fit whether petrol or diesel. The only problem you might find is that on older diesels the temperature sender is at the back of the head. In this case you may need to extend the wire (green/blue) to reach the sender. White wire goes to the stop solenoid on the injection pump, white/brown to the oil pressure switch.
Alternator wiring - most Defender alternators have a plug connector, Discos use ring terminals. If using the Disco alternator you will need to cut off the plug from the wiring loom and fit (crimp or solder) ring terminals - 4mm for brown and yellow wire, 6mm for brown wire(s). On the back of the Disco alternator are three terminal posts, 4, 5 and 6mm diameter. The 5mm terminal (marked W) is a sender for the Disco rev counter and can be ignored.
Clutch - petrol clutches are not as strong as diesel and should be replaced. Diesel clutches can be reused if in good condition, but I advise replacing the clutch unless it is fairly new. Or you can use the Disco clutch that came with your new engine if it is in good order. You don't want to have the engine out again for a good few years, so fit a new clutch if there is any doubt. Check the condition of the spigot bush in the back of the flywheel and replace if worn, cracked or loose. Make sure the new clutch plate is properly centralised on the flywheel. The absolute best tool for this is the end of the input shaft cut off a scrap gearbox. You can buy universal centralising tools, or the proper Land Rover tool if you are feeling flush. Some people swear by broom handles wrapped with insulating tape. Or if you are careful you can line it all up by eye. If the clutch plate is not absolutely central the end of the gearbox shaft will not be able to slide into the spigot bush and your engine will not go in.
Old gearbox input shaft cut off a scrap Defender box. The perfect clutch alignment tool.
Clutch release fork - these have a habit of wearing through at the pivot. Eventually the pivot ball punches straight through the fork. You can buy strengthened clutch forks which have a steel bar welded across the back of the pivot point, or you can do it yourself with a piece of thick steel and a welder. Always replace the release bearing even if you are reusing the old clutch. Check the condition of the clutch slave cylinder and change it is it shows signs of leaking fluid. It is not that easy to get to once the engine is in the vehicle and the exhaust in place.
The 300TDi uses mounts of an entirely different design to the earlier engines, and mounted in a different place. If you are fitting a 300 in place of the earlier 4 cylinder motors, and keeping the original LT77 box, the engine will sit around six inches further back than a 'factory' Defender 300TDi, so copying the mount position off another vehicle will not help. Three choices - cut the mounting brackets off the donor Discovery and modify them to fit, fabricate your own brackets (not too difficult as they are just a pair of flat ledges for the mounting rubbers to bolt to) or buy a pair of mounting brackets from the ever-helpful Steve Parker Land Rovers. These are self-jigging (using the bulkhead bracket bolts for alignment) and dimensions are spot-on. They take about ten minutes to fit. If you are going to make your own brackets you will need to drop the engine into the engine pay, bolt it up to the gearbox and support it in the correct position on a crane while you tack the mounts in place.
One other job you need to do is to remove the support bracket from the brake balance valve on the offside chassis rail and straighten it out to move the valve outwards. Otherwise the offside engine mount is liable to catch on the brake pipework and cut through it, leaving you with no rear brakes.
Now things get really exciting as you can fit your new engine. Fit the mounting rubbers to the engine but leave the upper nuts loose. Make sure that you have the engine absolutely square to the gearbox before you try to engage the input shaft with the clutch plate - if the two are at an angle the engine will not slide into place and you might damage the clutch plate trying to force it in. You may also have to engage a gear and rotate the engine with a socket on the crank pulley bolt to get the splines to line up. Be careful and patient and the engine will slide into place with a satisfying clunk. Refit and tighten the bellhousing nuts, then carefully lower the engine onto the mounts, making sure the studs engae with the holes in the mounting bracket. Tighten the top and bottom mount nuts (Nyloc nuts). The heavy work is now over and you can start plumbing in your new engine.