RGK Posted September 30, 2014 Share Posted September 30, 2014 Hi, Finally I've become an owner of my first land rover. Unfortunately time isn't on my side, twins on the way, project is on a friends drive, his wife is being very understanding & thus I don't want to push it. Please could someone assist ASAP We've mounted the 300tdi into the 90, however I've had a couple of issues with the engine wiring. The defender started life as a 2.5na 1986. Does anyone of a simple easy to follow guide to do this? I've read that some of the 2.5na cables such as the alternator & starter may not hold enough amp's to accommodate the 300tdi. Other connections such as the 300tdi cylinder head temperature sensor has dual connections, compared to the 2.5na single. Hence a easy step by step guide with photos would save me extremely valuable time. Thanks Quote Link to comment Share on other sites More sharing options...
Lewis Posted September 30, 2014 Share Posted September 30, 2014 It's been a long time since I fitted a 300tdi so I don't remember exactly the connections, but these general rules will still apply. I would run new 35mm2 cable direct from the battery negative terminal to one of the starter motor mounting bolts. Also run new 35mm2 cable from the battery positive terminal to the starter motor positive terminal. Run 16mm2 or 20mm2 cable from the alternator b+ terminal to the starter motor positive terminal. Trace the brown wires in the original engine loom which went to the alternator and connect them to either the alternator or starter motor positive terminal (these brown wires supply the rest of the vehicle loom with 12v) With regards to the coolant temp sensor - you will need a matched guage and sensor to get the correct reading, so if possible fit the original temp sensor from the 2.5na engine to the 300tdi (if the threads are compatible) and then use the original wiring Quote Link to comment Share on other sites More sharing options...
pete3000 Posted September 30, 2014 Share Posted September 30, 2014 I went the other way and fitted a 300tdi gauge in the inst panel, as the block had already got the sender, the other sensor wire is taped up (oil pressure?). The only additional wiring i did was the glow plug timer relay. I used my original ign switch, so i have off, then pos1 also is aux and run, then a sprung pos 2 for the red/white starter relay. Pete Quote Link to comment Share on other sites More sharing options...
Maverik Posted September 30, 2014 Share Posted September 30, 2014 I wouldn't;t be worrying about having to upgrade any wiring. If your truck is the same i.e. no more consumers being added i.e. air con, winch, lots of lights etc... then the wiring you have should be fine. The same starter motor is used in all the 2.5ltr diesel engines, it might pull a few more amps due to the higher compression of TDI, but I wouldn't worry. (I've got the original wiring in my 86 truck now running a 200tdi, and I've just put a 300tdi to replace an old Diesel turbo. The alternator on the 300 will no doubt be a little bigger in output than the NA engine, but its more the question of what you have running that will use the full output of the alternator. The old engine wiring loom should swap over to the 300tdi relatively easily... then its simply a case of connecting the same wires up to there similar places on the 300tdi (top temp sender can be ignored) and the defender type sender has already been mentioned. Quote Link to comment Share on other sites More sharing options...
Lewis Posted September 30, 2014 Share Posted September 30, 2014 I wouldn't;t be worrying about having to upgrade any wiring. My advice regarding upgrading of wiring was not because of the 300tdi being fitted necessarily, just prudent additions. carp earths and tired battery cables have got to be some of the most common causes of poor starting and electrical faults on land rovers. Why wouldn't you want the best? And when better to replace these cables than when changing the engine? The alternator on the 300 will no doubt be a little bigger in output than the NA engine, but its more the question of what you have running that will use the full output of the alternator.It's not what accessories you have fitted which should define the capacity of your alternator wiring but the output of your alternator. It doesn't matter how few electrical items you turn on if you have a depleted battery then the alternator will provide it's full output and you need cabling to accommodate that output. If going from a 2.5na (45amp alternator) to a disco 300tdi you would be more than doubling the output of the alternator. Personally I'm not about to trust 28 year old thin burnt copper wires to handle 100amps Quote Link to comment Share on other sites More sharing options...
western Posted September 30, 2014 Share Posted September 30, 2014 300tdi runs a 65amp alternator as standard fit, the n/a diesel might be running a 45amp alt, worth upgrading the alternator to starter motor cable at the very least. Quote Link to comment Share on other sites More sharing options...
RGK Posted September 30, 2014 Author Share Posted September 30, 2014 Thanks for the advice. Ive been round tonight 'in the rain', the things you do for your landy!! Ive taken the following pic's, can you advise/ clarify my assumptions, all of the below are 2.5na cables: Photo 010, is the starter cables, 2 x brown wires into 1 connection two off, plus the solenoid brown(red) & yellow wire. I don't know what the other green wire is for? Could be the cylinder head sensor?? Photo 006, alternator connection block, does anyone know which is th W, D+ & B+? , i assume the other green wire wihin the alternator loom is for the thermo? Photo 009, assume the white is the fuel pump soleniod, dont know what the other wire is? Great advice so far. All making sense. I think for ease, ie get'in on the road, I'll try to use the existing, then improve outside the house ASAP. When ive looked at the disco 300tdi loom to the 2.5na loom there seems to be major differences, or do I just replace the existing cable (previously mentioned) with larger? Thanks again Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 1, 2014 Share Posted October 1, 2014 Have a read of this thread and print out the sheets included, its the Lucas wiring colour list, it will give you some good pointers as to what wire goes where...http://forums.lr4x4.com/index.php?showtopic=21345 Quote Link to comment Share on other sites More sharing options...
RGK Posted October 1, 2014 Author Share Posted October 1, 2014 Thanks Quote Link to comment Share on other sites More sharing options...
Lewis Posted October 1, 2014 Share Posted October 1, 2014 The brown wires to the starter are 2 from the alternator and two from the vehicle loom. There should also be a battery cable to the starter In the second pic none of those wires go to the w terminal, the two thicker brown wires will likely need a ring terminal crimping on and go to the alternator b+ terminal, the thin wire is the sense wire and (I think) goes to the d terminal The green wire is for the coolant sensor The other wire with the stop solenoid wire is for the oil pressure switch I can't help with the rest off the top of my head, sorry Quote Link to comment Share on other sites More sharing options...
RGK Posted November 21, 2015 Author Share Posted November 21, 2015 Thanks for the help and advice. Finally got her started. Quote Link to comment Share on other sites More sharing options...
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