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Disco 300tdi onto LT77


v8bobber

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I have purchased a lovely (but painlessly slow) 2.5na 90. I know where there is a rusted out 300tdi disco and am considering buying it for the engine and axles.

I have done some searching on the web and also this forum but cannot find the definative answer as to if said engine will fit in the vehicle or not. Fabrication / welding is not a problem just need to know if it will actually fit on the box. Someone here will hopefully have done it / knows how to do it.......

Another quick one while i'm on, disco front calipers, there are two hoses going to the caliper, does this mean that each of the pots in the caliper is fed independant of the other one. The reason I am asking is that I am using front calipers on the back of my trialler and am in the process of plumbing in fiddles and want them to not be affected by the footbtrake

Cheers,

Dave

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Yup - you can either modify the LT77 bellhousing, or my preferred option is to remove the backplate from the 2.5 and bolt it onto the 300 TDi - then it will mate straight up.

Don't know about the calipers....

Thanks for that. Nice to know that it's possible. I remember that on a 200tdi the turbo position is different on the defender and disco. Is this the same with the 300? Or did Land Rover decide to to keep the turbos in the same place on the later engine. I'm assuming that you have done this conversion. Was the 300tdi from the disco or defender?

Regaards,

Dave

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I did a similar one - I replaced a 2.5TD and LT77 with a disco 300 TDi and a defender R380.

I purchased a front downpipe (I can't remember if it was a disco or defender one! Think it might have been disco) which met up with the rest of the exhaust quite nicely.

The only problem I has was the fan catching on the PAS box - I just removed the fan. I intended to fit an electric one to replace it...but being a TDi it never needed it.

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Others have covered joining the engine and gearbox.

Bear in mind the LT77 is several inches shorter than the R380 box this engine was normally paired with in a 90 so the engine will sit closer to the bulkhead.

You will also need to make new engine mounts or a new exhaust downpipe. The 2.5 mounts will bolt to the side of the engine and should all line up when you sit the engine in but the turbo exhaust output is then directly above the engine mount so a tightly bent piece of exhaust would be required. If you have the entire disco to play with and are happy welding then cutting of the engine mounts from the disco chassis and fitting them to the 90 is probably easier.

As far as I am aware all 300tdi engines are basically the same. The standard 90 exhaust wont fit due to the engine sitting further back but would only need a bit of shortening (if you use the disco engine mounts). If the engine still has an EGR valve and associated electronics throw them away, all the rest of the wiring should join up relatively painlessly.

Fan shouldn't hit the PAS box if the LT77 gearbox is used but will sit a long way back from the engine so either a cowling is needed or electric fans. The Disco radiator and intercooler with a bit of modification to the mounting frame will sit in place of the existing radiator, new pipes will need to be made up to connect it all together.

The PAS pump is needed on the engine for the drive belt or an idle would need to be made up and fitted in it place, if you don't already have PAS (not all early 90's did) the solution is to take all this from the discovery as well, it will just bolt in place.

Axles should just bolt underneath with no problems apart from the duel line brakes which you have already identified, for normal use the easiest fix is to T the two lines of the caliper together and run them from the normal brake line already fitted to the 90, you lose the duel line redundancy but an old 90 doesn't have this any way.

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I have purchased a lovely (but painlessly slow) 2.5na 90. I know where there is a rusted out 300tdi disco and am considering buying it for the engine and axles.

I have done some searching on the web and also this forum but cannot find the definative answer as to if said engine will fit in the vehicle or not. Fabrication / welding is not a problem just need to know if it will actually fit on the box. Someone here will hopefully have done it / knows how to do it.......

Another quick one while i'm on, disco front calipers, there are two hoses going to the caliper, does this mean that each of the pots in the caliper is fed independant of the other one. The reason I am asking is that I am using front calipers on the back of my trialler and am in the process of plumbing in fiddles and want them to not be affected by the footbtrake

Cheers,

Dave

LT77 to 300Tdi

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