2016 – Servicing the Unimog:

She is back home – But it was an expense “Service”

We went up north to AV for her service and some cosmetics. The fuel lines were connected incorrectly and the dashboard electronics were playing up.

Changing the Crown & Pinion:

I have been thinking about adding the AV Overdrive but at a cost of over £5K this has been a dream way after adding may other things to the truck. So when presented with replacing just the Crown and Pinion and going to 24:11 we decided to take the plunge. The drive home has been impressive. Instead of running 2500rpm at 55mph we are now running 2200rpm at 60mph. Not saying it is much quitter in the cab but I can already count the fuel savings. I did push her slightly and she went to over 60mph much easier. However we are not speed freaks and the win for me is the fuel economy and reduced wear on the engine. The impact has also more gear usage. Which I think is good. At just over £2K it is a much cheaper option than the Overdrive option. Naturally the limitation is that you cannot “switch-off” this option. But as we are not planning heavy off-roading, this is not a loss for us. Still enough power left in the tank!

The Good and the Bad…

Replacing the Crown and Pinion requires removal of the rear axcel and in this process the rear diff was opened. The good was that the rear diff was a complete mess! Parts had already fused together and a delight of metal shavings were floating in the oil. The metal shavings had already been picked up earlier and so it was good to find the cause. I clearly would not have taken long for the diff to completely fail. AV had a second had part which we could use and as the entire system was already in pieces the time and effort was significantly less than if this would have been a roadside job somewhere in Morocco.

The bad continued: Once we put everything back together I.e. New Crown and Pinion and new (second hand) rear diff we clearly had a waterfall effect on the portal axels…. As the new ratio results in a faster cycle and the repaired diff results in a smoother flow, the rear right side portal suddenly started running and significantly hot temperatures. Frustrating as the cause was not clear.

We are now the proud owners of a Fluke 63 Max+ and were checking the temp more often than we did with either of our sons when they were born. The temp (measured form the front of the rear wheels were running at 54-57 degrees Celsius (129 – 135 Degrees Fahrenheit).

This resulted in us having to leave the Unimog and come back a week later…The children enjoyed the extra train ride but we did not enjoy the extra train ticket.

Credit the the AV guys- they decided to take the portal apart and found metal parts floating around (!!!) The top bearing in the portal had also warn down and the extra space was the cause of the increased heat. Clearly there had been earlier repairs as the inside casing was severely damaged. (I thank my previous owners (the UK Special Forces) for the quality (NOT) repairs made). AV again had a good second had portal casing at hand and the bearing was also replaced.

So after some further minor (!!) repairs we were on our way home:

  • (Front Torque Tube Gaiter was replaced;
  • New door seals were added;
  • Hand brake was replaced;
  • Power Steering belt was fixed and power steering was fixed;
  • O/S Drag link Boot was replaced and
  • O/S rear Half caliper was replaced.)

Although the above was not cheap  – REALLY  – most of the repairs had been long term failures rather than new so we are expecting a repeat only after another 24 years!!

Our drive home was pleasant and I did like the fact that the engine was running at 2200rpm and remained in the green rather than 2500 and in the red.

What is next? Some spray paining….. and we are still looking for a better fuel monitoring system.

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