300TDi into Defender - some useful information

Guide for DIY fitting - by Glencoyne Engineering



Sooner or later I was alway going to end up putting a 300TDi engine into a Defender.  Until recently I have not felt the need to do the development work on this conversion as I could always find decent Disco 200 engines when I needed them.  But these are now getting harder to find, just as the bulk of 300TDi Discos are reaching the end of their lives. There are some major design differences between the 200 and 300 engines, even though they are the same capacity and power output.  So rather than just adding new information to my existing 200TDi engine fitting guide I have put together these new pages.  As with the 200TDi guide, this is not intended to be a bolt-by-bolt instruction manual. I am assuming that if you are contemplating an engine swap you already have reasonable mechanical skills and know that you have to take the old engine out before you try to fit the new one.  The idea is to cover the main problem areas and give you some idea whether it is a job you can tackle yourself, or whether you are better off leaving it to someone who has done the job before (i.e. me).


200 v 300 - which is better?

The 300TDi conversion has som advantages over the 200, and some disadvantages.  There is no clear-cut answer as to which is 'best ' - I usually tell people to find the best engine they can at the price they want to pay, and whether it is 200 or 300 they will be equally happy with the results.

Advantages of 300TDi:

  • Getting easier to find with sensible miles

  • Better long-term parts availability - used by the British Army (unlike the 200)

  • Allegedly smoother and quieter (to be honest I haven't noticed much difference)

  • Intercooler and air cleaner pipework easier to make up

Disadvantages of 300TDi:

  • Needs new mounts welding to chassis - major obstacle if you have a galvanised chassis

  • Exhaust front pipe tricky to fabricate

  • Some parts much more expensive than 200 (timing cover and fan pulley for example)


Why not convert?

If you live in London, or plan to drive there, you need to be aware of the new Low Emission Zone rules which came into force at the start of 2012.  Any TDi (or pre-TDi) diesel Land Rover registered after 1 Jan 1973, apart from factory-built Station Wagons (which are considered as cars and therefore outside the scope of the LEZ), will be charged £100 PER DAY to drive anywhere inside the M25.  This throws up a huge number of anomalies: some owners of genuine Station Wagons are finding that their vehicles are shown on the database, because they were registered with DVLA as commercial vehicles rather than cars when they were new. Some people have managed to get Nineties reclassified as Station Wagons by DVLA (after fitting rear seats and side windows), others have tried exactly the same request and been turned down.  There is no easy way around this one, and if you live or drive inside the LEZ and have a petrol engined Defender which was not built as a Station Wagon, TDi conversion is not for you. Apart from that, I can't think of any downsides at all to TDi converting your old Defender.  It really is the best value for money of any modification you can make to it.


Tools you will need

As well as the usual range of sockets, spanners, screwdrivers etc you will need the following:

  • Engine crane - ideally a long reach type.  The Defender engine sits a long way back in the chassis, and most 'budget' cranes will not reach far enough.  Distance from the front bumper to the middle of the engine is around 1000mm.  You can get an extra 150mm reach if you remove the front bumper.

  • 32mm viscous fan spanner - for removing the fan which you will not need.  It has a left handed thread.

  • Welder.  It is not possible to do a 300 TDi convrsion without being able to weld to a good standard.  You do not want your engine to fall out onto the road.

  • Brazing torch - for extending the oil cooler pipes (or you can buy them in - see below).

  • Crank locking tool and breaker bar with 27mm socket - if you are planning to change the timing belt (which I strongly advise).  Click here for more information on timing belt changes.

  • Angle grinder with thin cutting discs.

  • M10 (flywheel housing) thread tap.


Sourcing your engine

300TDi engines come in various forms - manual or automatic, EGR or non EGR, and the very late ones have fly by wire throttle.  What you ideally want is a non-EGR engine from a manual Discovery.  Automatic engines can be converted to manual but you will need to source a manual flywheel and housing, along with all the bolts.  EGR valve can easily enough be removed, as can the immobiliser unit fitted to the injection pump on later vehicles.  What you do not want is to end up with a late automatic 'fly by wire' engine - easily enough identified as there is nowhere on the injection pump to connect a throttle cable.  Avoid these unless you have a spare injection pump handy as well as the flywheel and bits.

The best way to acquire a 300TDi is to buy an MOT-failed Discovery.  That way you can hear the engine running and be sure that it comes with all the ancillaries you will need (see below for list).  Once you have taken the engine out you can send the vehicle for scrap and get some of your money back.

Next best is to buy an engine which is still in the vehicle, so you can hear it running before it is removed.  A hunt round the local scrapyards or on Ebay may turn something up.  Make sure the seller knows which bits you want, as breakers tend to just cut through all the pipes, brackets etc and cause a lot of damage taking the engine out.

The riskiest approach is to buy an engine which is already out and on the floor.  You can't hear it running and you only have the seller's word that it is any good.  It might even be stolen - avoid engines where the number has been ground off. An engine from a dealer or breaker may have a warranty, but if it turns out to be duff you still have to take it out and return it to get your money back.  You won't be able to learn much from looking at the engine.  Almost all old 300TDis are filthy, oily and look horrible and neglected. Check it actually turns over, look inside the oil filler cap for black sludge or white 'mayonnaise', look for major oil leaks from odd places and look for evidence that the engine has been left sitting outside uncovered (bright orange rust on the flywheel and front pulleys is a dead giveaway).

What parts do you need?  At the very least your engine needs to come with the following: Injection pump, power steering pump, turbo and manifolds, alternator, starter, flywheel and housing, engine mounts, radiator/intercooler assembly, intercooler top and bottom hoses, air filter intake hose (although you do not need the airbox).  Ideally you want the fuel filter housing (essential if converting from petrol).  Petrol conversions will also need the glow plug relay and wiring harness, and possibly the battery positive lead. You don't need the cooling fan.  If the starter is missing, the 2.5NA or TD starter will be a straight swap provided it is the later Bosch or Paris Rhone type, not the big bulky early Lucas version which will foul the turbo.  The starter from the 2.5 petrol will not fit. If your donor vehicle has air conditioning, grab the twin 11 inch fans from the front. If you have a vehicle without power steering and are planning to convert it, salvage the old power steering box from the Disco along with the fluid reservoir.  Even if the box is shot you will need it as an exchange unit.

How much to pay?  I expected 300 TDis to be a lot cheaper by now, but apparently there is a healthy export demand as the engine is near enough identical to the Defender version.  Price for an engine complete with ancillaries as above seems to have settled around £450-500, and MoT-failed complete vehicles can go on Ebay for £800 or more, which is a bit silly really.

From your old engine you will need the wiring harness and nothing else. The rest you can sell for whatever you can get for it.  Don't expect too much unless it is in really good shape, and try to find a buyer before you take it out - so they can hear it running and pay you more for it.

Next - preparing the engine to fit - click here


300TDi guide page 1

300TDi guide page 2

300TDi guide page 3

200 / 300TDi questions and problems