This was one of the tasks I wasn’t looking forward to. I have to say that I don’t like drilling into chassis tubes, it’s not one of my strongest skills. I have also had an experience, where the expansion tank cap on a 420R S3 touched the nosecone (because the lower Dzus fasteners hadn’t been secured properly). The result was a dent in the nosecone and paint. Therefore I am aware that clearance on a S3 is very tight.

Before I started, I removed the tie wraps from the chassis tube. I will refit them once completed. I wanted to assemble the expansion tank brackets to find the best position, but ran into my first problem. The bolt which holds the two brackets together wouldn’t pass through, so I had to clear the hole with the drill.

Next I had to make a choice: the S3 420R I have seen, had the main hose routed into the corner of the chassis. This resulted is a less than optimal route for the small hose near the cap. It was pointing directly at the dry sump tank. The alternative was to route the hose around the front chassis tube, in between the chassis and the front ARB. This results in a fantastic small hose route.

I actually ordered the hose I tested my routing with by mistake. I ordered the wrong colour, so I was happy to use this as a test, cutting it where needed until I was happy.

I used different colour masking tape to make sure I was happy with the location, as well as to secure the bracket while I fitted the nosecone to test the fit for the first time. Thankfully I had good clearance between the expansion tank cap and the nosecone, so I felt happy to proceed to the drilling part.

As I said drilling, isn’t my strongest skill. I managed to get three holes where I wanted, but one was slightly off, thankfully the rivets permitted enough play to mask this mistake. I took the opportunity to paint the holes I drilled with POR15 chassis paint and fill the chassis tubes with ACF50 anti rust oil, before riveting the expansion tank bracket in place. For convenience decided to use the hand pop rivet tool instead of setting up the air powered tool. Unfortunately this always seems to damage the black rivet heads, so a little more chassis paint was used to touch them up (still wet when the photo was taken).

16mm 135 degree silicone elbow hose and Gates 19mm to 16mm reducer

I decided to not use the kit-supplied U shaped hose, because the hose goes from 16mm to 22mm in the U bend, making getting a tight seal on the connection with the expansion tank difficult. I had this particular problem with my 360R; it would occasionally dribble a little bit of coolant from the expansion tank joint, but only after it was run while it cooled down. The solution I found was to fit a 16mm hose and a reducer from 19mm as fitted to the T piece. The reducer I used is a Gates item, designed for automotive cooling applications.

With the expansion tank fitted, I could finally move onto the plumbing. All the silicone hoses where secured using Mikalor Supra clamps and the smaller rubber hose using genuine stainless steel Jubilee clamps.

Tools Used

  • Hammer
  • Centre punch
  • 13mm 3/8” drive socket
  • 3/8” drive ratchet
  • 7mm 1/4” drive socket
  • 8mm 1/4” drive socket
  • 10mm 1/4” drive socket
  • 1/4” drive ratchet
  • Electric drill
  • Knife
  • 7/16” combination spanner
  • 1/2” ratchet ring spanner
  • Ruler
  • Side cutters
  • Pop riveter
  • Dzus screwdriver