Aux Radiator Install
We were kind of in a hurry to get this in as we were doing it the evening before we were headed out to the track, so I didn't stop and take as many pictures as I would have liked. But, I have a few, and there are a few things that I'd do differently if I were to do it again.
To start, you take the bumper cover off and drain the coolant by disconnecting the hose on the passenger side of the radiator. I have a CSF radiator installed that allegedly has a drain plug in it somewhere, but I couldn't find it and you have to disconnect that hose anyway.
Next, you want to get the front cooling stack/bumper into the service position. So, take a bolt out on each side, put in longer bolts to support everything, then take the other three out. If you pull everything toward you a little, it makes it easier to see what cables need to be disconnected on either side. Just don't pull so much that you rip any of them apart. Then move the long bolt you have on the driver's side over to the passenger side and swing everything over.
Now to the hard part. Putting the radiator itself in is pretty straightforward. There are two studs on the car that the bracket hangs on, and one stud on the bracket itself that gets a nut on it from the other side. There's a hole in the bracket that you run the hoses through. The duct clips right on. You will (probably) have to loosen the nut on the horn and spin the horn around so that you can clip it on. Also, you'll have to reroute the wire for the horn because the bracket goes over the top of where it runs originally.
As I mentioned before, you need 3 grommets to install the radiator. There is one on the top as well. But, if you only ordered two like me you can use a shift rod bushing from a Mk1 GTI as it's pretty much the same size. Everyone just has some of those laying around, right?
You'll have to take the fan shroud off to mount the hard cross tube. It mounts as far as you can get it towards the passenger side of the car.
The hose from the water pump coupler to the cross tube took more time than the rest of the install combined. As I mentioned in an earlier post, the hose is different sizes on each end. It's 18mm on the water pump end (I'm 95% sure...I did measure it, but I forgot to make a note) and 15mm on the side to the hard line (99% sure of this one...I measured the hard line to buy a generic hose that I intended to use here). It's also a really tight bend, so I did a lot of trial and error cutting off more and more until I could get the hose on without it kinking in the bend. If I were to do this again with all factory parts (hold that thought) I would probably just buy the factory hose assembly. The hose also can't stick up too high, or it'll be against the hood.
(Forgot to take a picture after I finally got it on, because it was getting dark and there were many mosquitoes.)
You'll also want to put something around the hose because it's going to be up against the fan shroud.
If I were to do this again, I think I would put some kind of 15mm to 18mm adapter in place of the hard line. You have to drill holes to mount the hard line anyway, and a shorter adapter of some kind that goes into the OEM hose from the aux radiator would give you more flexibility to get a generic 18mm hose in there. The longer path for that hose from the water pump to the adapter would also make it easier to make that bend without worrying about kinking. Otherwise, I'd spend the $180 or whatever to just buy the OEM hose assembly.
Also, I'm not sure if someone else has looked into this, but I might swap out the fan shroud altogether for the R shroud. The GTI shroud is a bit thicker, which makes that bend even tighter for that hose. Also, with the CSF radiator and Unitronic intercooler, the shroud has already been pushed back into the engine bay a bit. I had to put some sleeves on the charge pipe on the driver's side and one of the AC lines. The R shroud has 2 fans, so I'm not sure what all it would take to make that work.
After that, you can put it all back together. As I mentioned above, I tried to get away with just using a fog light grill to get air into the radiator, but it doesn't line up. So, I ended up just drilling holes into the bumper. I'll clean it up a bit some other time. I probably won't bother with an R bumper. I don't mind the holes so much, especially once I get them cleaned up. And, the bumper plus paint is money I'd rather spend on other things. Also, my car has over 100k on it, and a freshly painted bumper would look a bit out of place I think.