Converting an OM366 to OM352 – or saving Myrtle from becoming an ornament.,

One of the things I enjoy about living on the Rock Farm is the range of problems I come across. From animal welfare and soil management, to rural plumbing and fencing repairs, I love the process of learning new skills. Regular readers will know, last August, I drowned the engine of our old LA911 Benz, Myrtle, attempting to cross our creek. With pride bent along with the conrods, I was in need of a new engine for our red ;drawbridge’. One of our neighbours collects old trucks and offered to sell me an engine out of a similar truck, a Benz 1217 Tipper.

An initial check seemed promising, however after consulting the Mercedes Kurzhauber (short bonnet) Facebook group I realised I had incorrectly identified the donor engine as a turbo charged version of the the OM352. It wasn’t. It was an OM366 – a much modified variant that shared little with my engine except the block. Perhaps with the ignorance caused through auto-translate from German Engineers active on the Facebook group, I figured that it shouldn’t be too hard to make the engine fit. After all I had nothing to lose.

I should have done more research…. but then if I had I might not have proceeded. The German Engineers were wise with their words of caution.

For the next five months I had three new items on my to do list:

  • Remove Engine from Myrtle (Our LA911)
  • Remove Engine from Donor (The 1217)
  • Install Engine into Myrtle.

It wasn’t until I had completed the first two items on my list and placed the two engines side by side that I had some idea of the challenge ahead of me. The engines looked entirely different. There should have been one more item on the list – something along the lines of reconfiguring the new engine to look like the old one.

I took a deep breath and started at the front of the first engine. I thought it would be simple to swap the fans over – the most obvious difference…. but first I needed to change the water pumps…. and then the water jackets didn’t line up – and so off came the turbo and the other plumbing from the new engine. Eventually we got one side of the engine looking close – and then it was time to pull off the bellhousing / clutch at the back of the engine. This again was challenging on the old engine as I couldn’t turn it over. This meant I couldn’t reach all the bolts holding the clutch plate to the flywheel. After modifying some tools with a grinder, and some help from a smaller handed wife, this challenge was eventually overcome.

And so on and so on. Every time I thought I had sorted one problem, another five were created. Swapping the sump turned into a full day job with the cascading series of other little things that also needed to change. Literally everything short of the block and cylinder head was swapped over from one engine to the other. My dreams of gaining some extra horsepower were whittled away as the new engine was reconfigured almost exactly as per the original engine.

Eventually we had swapped nearly every thing over. My biggest fear was that I didn’t get the timing of the fuel pump correct, or that I had put the clutch plate in back to front (of course I reused the old one).

I also found it extremely difficult to manoeuvre the engine to align with the gearbox, no matter what tricks I tried. Eventually I opted for a different approach and disconnected the prop shaft and slid the gearbox back. After bolting the engine in position, I was able to (with the help of all the family) push the gearbox up and bolt it to the bell-housing. It was no small feeling of joy when at last everything was bolted together. But would it start.

There was only one way to see….

To say I was relieved when the new engine spluttered to life would be an understatement! And thankfully it seemed the clutch and gearbox was all aligned correctly too.

The truck was pressed straight back into service – moving old roofs of iron sheeting to make new compost bins. And the not-so-little welder was commissioned to make a feature out of the donor engine’s fan. He did a great job fashioning a windmill out of some scrap steel.

With the truck back in working order, I was able to get back to the other things I love doing on the Rock Farm. Hanging with my bovine friends, and installing new gates to facilitate my ongoing paddock rotation. I hope I don’t have to take on a mechanical challenge of that order again, but it was a good exercise in working through a problem and I am thrilled to have a working truck again on the Rock Farm.


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