The Unimog Engine is a 5.7 litre straight 6 diesel. It’s still on its original engine, however we did have it modified to add a turbo charger, and an uprated fuel pump. This work was completed by Atkinson Vos in the UK before we left on our trip. The logic was to let the engine breathe a bit better on the high altitudes that we will experience in South America. The Unimog Engine (352) is a very popular engine in South America as it was used in many trucks and buses over here.
The engine has no “Glow plugs” which means it gets no help when starting from cold. The coldest/highest we have started it was in Bolivia, when we started it before dawn at -11 Celcius at 4000 metres (roughly). It was not too happy about it, but fired up and off we went!
Our Mog (there are many different models) had 8 gears forward, and 4 reverse. We need to let the air pressure build up to allow us to change from the lower 4 gears (1-4) to the higher range gears (5-8). Moving from the lower range to the higher range is done with the single gear lever, but you can hear an air pressure release as the compressed air is used to shift some of the gears. You cannot go into the high range gears while in reverse, which is probably just as well!
We have a sticky 5th gear, which does not like being changed into when the gearbox is cold, but once it warms up it’s fine. So, morning gear changes are usually 4th – 6th – 7th – 8th.