Unimog Maintenance

Its maintenance time again...
"Unimogs are great bits of kit,... if you look after them."
A phrase we have heard many times since taking delivery of our U1600 Mercedes Unimog from Atkinson VOS Ltd.
As with any vehicle of 25 years there is always going to be some issues to address.
Ours had started producing some smoke from the exhaust after working particularly hard on a water vole fencing job in Essex. There was also a fairly strong smell of partially burnt diesel. This called for some examination of the big block of iron at the heart of the beast... the 6 litre, 6 cylinder engine.

First of all, we had to raise the cab to give all-round access to the power unit. Unimogs do have a removeable bonnet and front grill but this only gives partial access to the engine.
On examination we discovered that our Unimog didn't have the necessary hydraulic, hand-pumped ram fitted to raise the cab so we had to use an arrangement of lifting gear and lifting straps to do this job. Suprisingly few pipes, cables and other services required disconnecting before raising the cab. Only the air intake pipe from the air filter, and a couple of heater hoses.

With the cab raised it was possible to get clear access to the top of the engine. We employed our local mechanic, Ryan from 'The Garage' to do the engine work for us. Rocker cover was removed and diesel injectors prised out of the block. These were sent away for testing. Diesel injectors should produce a nice uniform spray pattern, testing showed ours to produce more of a dribble. This clearly explains the smell of partialy burnt diesel and reduced engine performance. New diesel injectors were fitted and diesel filters replaced to help protect these new injectors.

Lowering the cab was more tricky than lifting. First of all we had to ensure that the splined steering column shaft lined up with its other half (The steering column separates when lifting the cab). It was then a case of very gently lowering the cab to its mountings whilst a collegue checked that no wires, pipes, fingers or other bits n bobs were going to be trapped when the cab came to rest.

Once the cab was back sitting on its mountings, the 4 securing bolts on the floor pan, inside the cab, could be put back in place. 3 of the bolts went in ok but one could not be located due to a very slight misalignment of the cab. The cab must have twisted very slightly on its pivot points when lifting. With 3 of the bolts in place, we started the engine and drove a short distance to allow the vibration to seat that cab correctly, enabling the 4th bolt to be fixed.