September 07 Update, Tdi on the Horizon

The 109 is still running well, and I have been running it on vegoil for the drive to work. It doesn’t seem to consume any noticeably larger quantity than it did diesel. There is still no detectable performance difference, and the engine is still running smoother, quieter and with less smoke than on diesel.

I have found that using vegoil instead of the previous test with sunflower oil affects the throttle response on pedal release – the engine takes twice as long to run down to idle. I suspect this is just due to the higher viscosity of the fuel affecting the injection pump govenors. I will use sunflower oil when available until I start filtering the waste vegoil.
I am now considering an about-face on my plans to rebuild and fit the 19J turbodiesel engine in my garage. As you all already know, that engine is very similar to the existing 12J 2.5 normally aspirated diesel, sharing the majority of its components. Apart from the exhaust downpipe, it would be a straight swap.

The change of mind is down to the fact that I have been offered a running (MoT holding) Discovery 200Tdi. The present owner is removing the gearbox and wants the front axle, but wants to sell the rest of the vehicle to me for £450. That means I get a complete 100,000 mile (not much for one of these) 200Tdi engine, all of its accessories and fuel, coolant and oil cooler assemblies, and any other associated spares for less than 1/4 the cost of getting a stripped 19J from any of the reputeable rebuilders. Furthermore, I get the rest of the Discovery, which I can remove a few spares for my Range Rover before selling everything else off at a slight profit.

The benefits, other than cost, of going for the Tdi are a more robust engine, more power and torque than the 19J, an engine that won’t struggle to keep cool in arduous conditions and 20% better fuel economy.

The overdrive was replaced with the RM Roverdrive, so will be of no concern. Nor will the Series transfer box, which is stronger than an LT230 (Defender, Discovery). I still have concerns over the Tdi’s torque being excessive for a SIII gearbox. The 200Tdi in Discovery guise gives 111bhp and 195’lb. The SII/SIII 2.6 straight six had about 95bhp, and the maximum torque for a SIII box is about 160’lb. In order to keep torque down to acceptable levels, I will be installing it without the intercooler. JE Fearn estimate this will produce about the figures I want. Of course, this will also make installation simpler.

I will use the Tdi radiator and integral oil cooler. I plan to install these on the top of the front cross member, with the original radiator mounting panel top and sides cut to suit. This will hopefully allow me to use the Tdi’s viscous fan rather than using an electric fan (which I don’t trust).

The plan is to aquire the vehicle this autumn, allowing me to fit new big end and main bearing shells, total seal piston rings (dearer but better than normal rings), replace the head gasket and inspect the oil pump before installation in the spring. It has to be complete a few months before the expedition to allow for trouble shooting.