Oil cooling is standard in the Roadster so it is a good idea if you have a modified fortwo to consider a form of oil cooler.
DIY Oil Cooler
It's one of the most over looked mods on the smart yet it can be a cheap
and easy mod to achieve using a few parts and a bit of imagination.
There are three possibilities to oil cooling on the smart.
Fitting a Roadster oil/water heat exchanger
Using an adapter and a take off plate
Using an adapter and increase cooling around the filter.
Fitting A Roadster Heat Exchanger
This mod was originally performed by forum member Wizzkid
Both the Roadster and the diesel fortwo had oil/water heat exchangers to cool the oil.
This mod will only work on a 700cc smart fortwo engine as the 600cc engine uses
one of the connections (to cool the turbo) that we need to use for the heat exchanger.
Here is the heat exhanger, it is built into the oil filter block.
Look under the car you will see where the two black pipes will terminate.
Looking into the top of a dismantled engine you will see the water routes.
The coloured dotted lines indicate how far you have to drill for each hole.
You will have to drill four holes in total:
2x fixing points
Use a 10mm drill to make the red and blue circled holes. You have to drill into the first cavity you find.
The fixing points will have to be drilled and tapped or drilled and helicoiled.
Check the holes on your heat exchanger but M5 or M6 should be about right.
Ensure that the mating face is clean and clear of swarf and that the pipes have the rubber seals in place.
This information will be updated as and when I can get the info.
Adapter And Take Off Plate
Thanks to Kevin Hampson for the pictures.
You need to have bought a Mocal oil filter adapter as seen here.
This replaces the plastic cover and tiny filter fitted as standard on the smart.
This is the extra part we will be fitting, it is a thermostatic take off plate also available from Mocal.
When the oil is cold, the valve opens and the oil goes from the filter back into the engine. When the oil reaches about 80 degrees, the valve closes which forces the oil out of the adapter and through a radiator.
You don't have to use a thermostatic take off plate, Mocal also sell direct take off plates
that always routes the oil through the radiator. It isn't recommended as the oil takes
longer to reach operational temperature and can cause excess wear to the engine.
The take off plate screws in between the oil filter adapter and the oil filter. The outputs can be
placed depending on where you are placing the radiator. Remember to oil the rubber seal of
both the filter and the take off plate to increase the seal between the parts.
From this point you just have to plumb in the radiator and find a suitable mounting point for it.
Luckily, the engine has many torx bolts that can be used for mounting things like radiators.
This shows Kevin (Diverat) Hampson's version of the modification.
He has take some sheet aluminium and added a few bends and and
supports and joined it to the engine using some of the existing bolts.
A hole was cut from the panel and a scoop rivetted to the underside. Kevin also added some
foam seal around the outside of the hole to increase the airflow through the radiator.
Two pipes are made up to the correct length. Kevin found that heating the pipes in
boiling water made it easier to push them onto the connectors. The right angled connections
are tightened to the radiator and the other ends to the thermostatic take off plate.
You can make your life easier by filling the radiator and pipes with oil before
plumbing it to the take off plate. This reduces the air that can become trapped.
The radiator is then bolted into it's final place.
The scoop catches air from under the car and forces it through the radiator,
this cools the oil passing through it.
Personally I would add a bit more support to the radiator but this one has been
in place with no problems for some time now so the weight must not be a problem.
Similar setup to the horizontal radiator except (obviously) the angle of the radiator.
The one pictured below is made by S-Mann and has to be the nicest radiator kit I have ever seen.
The radiator is bolted to the engine using custom stand offs and is plumbed with hard pipes.
To replicate the design would be easy and it would be far easier with flexible pipes.
The scoop under the radiator could be made from aluminium or carbon fibre.
Increase Filter Cooling
This mod was originally done by forum member Waflo.
This is hardly a professional solution but an idea to consider none the less.
Many years a go I bought an oil filter heatsink for my previous car, it was never fitted.
It cost me about £5 from Ebay and this particular model was made by CT Racing.
The idea is simple, it pushes over a standard size oil filter and acts like a heatsink increasing cooling.
Once pushed over, the bolts were tightened down onto the filter to keep it in place.
It didn't fit my last car because a part of the engine was in the way, same with the smart.
Just above the oil filter canister is the drive shaft and drive shaft bearing boot.
To get around this problem, I cut a section from the aluminium heatsink.
This gave enough room to slip the heatsink over the filter.
The only thing left to do is to work out a way of fixing the cooler tightly in place.
Waflo (the creator of this mod) opted to use jubilee clips, here is his finished cooler.