Engine build and paint

In Mini Big Rigs•7 Minutes•By NZ Trucking magazine•December 14, 2020

It is time to fill the gap at the front of the chassis between the rails with a twin turbo V8 beating heart to power our Mighty Merc..

Photo: Step 1 – Preparation: select all the parts required for the engine assembly, lay them out, and prepare them for glue.

If this is your first time building a 1/25th scale or greater kitset model truck, you will find it is quite a unique experience compared with other vehicles. With the likes of cars, planes and even boats, a lot of shortcuts are taken by the kitset manufacturers to simplify the assembly process for the hobbyist, and this results in a lot of build detail being lost. In comparison, when building a model truck you will find there are many similarities to the actual build process of the real rig. Just like they do nearly 470 times a day at the Mercedes-Benz heavy truck factory in Wörth, Germany, we started with a pair of bare chassis rails and began the process of building our tractor unit. Moving forward we now need a power plant and gearbox to sit between the rails of the chassis. So looking at ‘step 4‘ of our instruction sheet we find two stages to the engine and gearbox build. Once again I find it convenient to first accumulate all the numbered parts required and lay them out on the work bench. This way you can descale any flash or clean moulding lines before beginning assembly.

There are a couple of parts that look similar (cylinder heads – parts 58 and 59), however they fit on specific sides of the engine block, so sitting them on a piece of paper and numbering them helps save confusion once you start gluing. My approach is to assemble all the engine parts in their factory-finished bare plastic state as detailed in the instruction sheet, and leave the painting and detailing for later on once the engine is complete. This speeds the process, reducing fiddly gluing of freshly painted parts where you inevitably end up with visible glue between the various parts. Also, the base colour for the majority of the engine components is the same, and again it is how most real life-size engines are painted in the factory. For ease of painting the cooling fan and drive belt details, I leave the radiator assembly (parts 64, 65, 66, 67, and 68) off at this time, as it is easy to fit these later once the engine painting is complete.

Photo: Assemble the engine in its bare factory-finished plastic state as this will make painting that much easier and achieve a clean finish.

Photo: By leaving the radiator assembly off initially you have greater access to the fan and drive belt assemblies with your paint brush to detail paint.

Choosing an appropriate colour for the engine is as simple as a quick Google image search for ‘Mercedes-Benz truck engines‘; this immediately reveals a plethora of colour options for the Merc. There are greys, blues, and every shade of green; if only we were painting a CAT C15. Looking at the image search I find a photo that matches a pot of Tamiya XF20 Deep Green that I have on the shelf, so that is what I have used. There are many options at your local hobby store when it comes to paint. Like a lot of other modellers, I have opted for the newer acrylic enamels, as they are very user-friendly, simple to apply, and clean-up is with water. Have a chat to your local stockists regarding the options and what fits best for you. I start by applying the green to the engine block. Once this dries I can then paint the various details; brown for the exhaust plumbing and turbos, black for the rubber hoses – again, use Google images for guidance here. At this stage now that the engine is finished and painted, I go about the installation of the radiator assembly and its plumbing. First of all glue parts 64, 65 and 66 together and paint; I used Tamiya XF84 Dark Iron. Once this has dried, glue into position – at the same time gluing into place the two radiator hoses, parts 67 and 68. When these parts have set and dried you can go about painting them. The final area left to paint is the gearbox, and again a Google image search reveals that a Satin Black appears to be a common colour used, so I applied Tamiya XF84 Dark Iron here as well as it has a little more character. We are now set to power up the mighty Merc with its period twin-turbo V8. Next time it‘s all about wheel assembly and working towards a rolling chassis.

Photo: The finished twin-turbo V8 ready to power the Mighty Merc.