Thanks to Kayble for the pictures and information.

Removing The Intercooler

Remove the back panel - detailed here. You will be left with:



 Remove the rear crash bar. 



 Remove the TIK hose. There's a jubilee clip at the airbox and another at the turbo. Don't forget to recover the seal that goes round the turbo inlet. With the TIK removed, you'll see this:



Remove the exhaust. This helps a lot with accessing the intercooler hoses.
Working from the top of the engine, remove the upper intake hose.



Unplug the intercooler fan and unclip the the wiring loom section that attaches to the fan.
Using a pair of pliers pinch together the two tabs in the top middle of the cooling fan assembly
to pull it away from the intercooler. Rock the entire fan assembly forward and away from the
top of the intercooler and the bottom fan clips will unclip - but be gentle with it.



Unclip the intercooler air temperature sensor connector from the bottom of the
intercooler housing. Unclip the sensor from the connector coming from the wiring loom
and set the sensor aside somewhere safe - it's fragile. The sensor is located to the
lower left of the intercooler when looking from the rear of the car and looks like this.



Remove the pipe clip from the bottom of the EGR valve the remove the lower intercooler hose.



Undo the jubilee clip on the hose at the intercooler end then manipulate the
hose off of the EGR valve then off of the intercooler.



Remove the lower intercooler/turbo inlet hose. Undo the jubilee clips at both ends and manipulate those out. This one is a royal PITA to get out by the way! It looks like this.



Remove the intercooler. It is secured by four plastic clips on the top and bottom of each side.
You need get a thin flat bladed screw driver and carefully press it in to the centre of each clip to disengage it from the plastic housing, gently pull it forward. As with the cooling fan, pull the top of the intercooler forward and away from the rear housing first. You can then lift the intercooler up and out of the engine bay. Be careful not to damage the semi rigid diesel fuel return line or any of the wiring loom parts as you remove the intercooler. With intercooler out, you will see the air scoop housing as shown below - with the plastic clips that engage with the intercooler.



Extended Information
Many thanks to Elar for this usful tip.

With the intercooler removed you should check to ensure that the 2 bolts holding the intercooler
scoop (circled and arrowed below) are in place and tight. Apparently it is common for one of these
bolts to be missing which allows unnecessary movement of the scoop.



Where Does The Intercooler Leak?

The intercoolers in diesel 450 fortwos are prone to vibration/play damage issues against the
air scoop housing that the intercooler sits in. With this in mind look at the intercooler a
bit closer. You may need to clean it to see any damage as oil will have been leaking over it.

This is the side of the intercooler you see when you look in the engine bay.



All looks ok on this side of the intercooler as expected. However, if you look at the back...

This is the lower left corner of the intercooler. You can see some light indentations towards
the bottom of the metal assembly where the intercooler has been rubbing against the lower
lip of of the intercooler/air scoop housing. There are also some more indentations slightly up
the intercooler by the plastic clip that holds the intercooler on the housing



It looks like it was well on the way to having the common fault shown on a Canadian IC below.



It is possible to braze the holes up if you have the talent and tools although a new IC is easier.
Smart part number Q0002490V006000000.

On this particular IC, the indentations had not yet perforated the intercooler fins.
The leak had to be coming from elsewhere. The next likely candidate was the end crimps.



If you look at the intercooler, you can see that it has a top and bottom plastic piece
with a metal finned assembly in the middle. The top and bottom pieces are 'crimped'
tight in to the metal piece however you can see that in the above shot, the crimps
are giving way and, I believe are allowing oil to seep out.

A few methods were tried to fix the leak but nothing was permanent. Sealing with silicone
lasted a few days but silicone reacts badly to oil, so soon started leaking again.
Obviously there is a lot of force involved when the IC is made, it's not something
that can be repaired that easily so unfortunately, a new IC had to be purchased and fitted.

For reference, the part number taken off the intercooler is Q0002409V007000000
These can be bought from smart but don't expect them to be cheap.

If you really feel that you have to repair your old IC, try using liquid gasket that is
designed to seal the oil sump in place. It is designed to work with oil and heat.

Curing The Rubbing Problem

There is no point in fitting a new intercooler if it is going to rub against the intercooler scoop
and develop a hole in a few years. The answer is to cut the leading edge of the scoop back.



This job is probably best done with a hacksaw or a rotary tool like a Dremmel.

And that's about it, reassembled the car which is the reverse of taking it apart.

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