This is only a guide on how I did it, I take no responsibility if you damage your car or harm yourself in any way doing this.
My lupo is 2003 and has no aircon. Got my radiator from eurocarparts as online you have 5 different options. Here’s the rad code I had. I’m not sure if it’s still the oem radiator. Might as well put a new thermostat in whilst you’re at it. I ordered one with the housing that connects to the radiator hose as apparently they are prone to breaking. MK2 suggested flushing it with dishwasher tablets as the system was oily so I did it 6 times. Dissolved a tablet, put fresh water in with it, ran the car for 20 minutes, waited til it hit about 50c on my obd scanner(can buy them for 20 quid on eBay) and drained all the water. I’d then wait about 30 mins until it said 30c before flushing it with a hosepipe. You don’t want to put cold water into a hot engine! It cleared up all the oil too. Top tip, remove the thermostat for a better flush experience. I also assume that you have knowledge on flushing an engine. For the thermostat, I’ll add some pics with instructions to this thread once my new one comes.
10mm socket with a driver and an extension
8mm socket for thermostat housing
torque bits(unsure on size)
pipe pliers( to remove the horrible spring clips from the hoses)
Then wrap some tape around a flat screwdriver to pry out the indicator grill cover.
The little white plastic rivet things might break so have some spare ones if you can. Once you’ve popped both sides, gently pull it out and use the screwdriver to push out the plastic tabs all along the bumper and the top. You’ll see them from above once you start pulling them off. Also unscrew the indicator bulbs to get it off completely. It’s easier to unscrew them as opposed to getting the clip off the bulb.
it should leave you with this
Undo the three supports and pull them back. Someone grinded mine off in the middle. Once you’ve done this, you’ll have space to pull out the radiator. Now we’ll go and disconnect the radiator from the cover and hoses.
Use the 10mm socket to remove the fan as it’s easier to get to the hoses that way. If yours are like mine and the bottom bolt is rusted on and just turns, remove only the top two and tie it to the left of you. Remove the fan plug and the radiator temp sensor plug too. You’ll need to pry off the metal bracket on the fan plug with a flat screwdriver, it should then just slide out.
We’ll remove the hoses now whilst the radiator is still bolted in. Make sure it’s not hot or you’ll burn yourself.
whilst I was doing this I disconnected the overflow bottle, tied off the bottom feed and put some degreaser with boiling water in. Left it for the duration of me fitting the radiator then flushed it with a hosepipe for ten minutes.
Now that you removed the pipes with the pipe pliers, there are 4 10mm bolts to remove.
Your radiator will now slide out of the front where the brackets are. Make sure you take it easy so you don’t damage the new one going in. If your radiator is brand new, screw the bolts in halfway as it needs to cut a new thread into the plastic and it’s a pain when the radiator is already in the car. Remove them and then install the radiator. You can also remove the fan temp sensor and install it to the new one whilst it’s out. Everything is now in reverse. Put the new one in, bolt it in and connect the bottom hose. Bolt the fan back in, plug the fan and the sensor in. Before you put in the new thermostat or attach the top radiator hose, start filling the top rad hose until coolant starts coming out of the top of the radiator. Connect the top rad hose, install the thermostat, connect the hose at the bottom of the overflow tank and fill that up to the maximum level. Make sure all is connected and start the car with the coolant cap off. Once the thermostat opens, you might have to add more coolant and keep a close eye on the cars temperature. Once you see the coolant circulating and it doesn’t want more, close the cap to pressurise the system and check for leaks. Your coolant light might start flashing, if it doesn’t want any more coolant, switch the car off and on to reset the coolant light. Now keep an eye on the system. You’ll see steam from the radiator, this is normal as we’ve spilled coolant and water all over. The fan should come on at 96c. If you haven’t got the obd diagnostic tool, you won’t know but wait til the fan comes on and the temperature is stable for about 20 minutes. If so, put the grill back on and go for a test drive.
Hope this helps at least one person.