{"id":860,"date":"2017-09-23T23:58:15","date_gmt":"2017-09-23T22:58:15","guid":{"rendered":"http:\/\/www.purplemeanie.co.uk\/?p=860"},"modified":"2026-05-28T01:08:44","modified_gmt":"2026-05-28T00:08:44","slug":"build-session-17-engine-bay-plumbing","status":"publish","type":"post","link":"https:\/\/purplemeanie.co.uk\/index.php\/2017\/09\/23\/build-session-17-engine-bay-plumbing\/","title":{"rendered":"Build Session 17 : Engine Bay Plumbing"},"content":{"rendered":"\n

Now back from the US and the after effects of hurricane Irma… I have some more time to get on with the build. I’d left the project at the point where I really needed to get on with the engine bay plumbing and I’d laid all the hoses out in the engine bay prior to the trip. The 5\/16th” water expansion bottle hose was missing from the kit but while I was in the US I’d emailed Derek and the hose had arrived while I was away… so first task was Water Expansion Bottle.<\/p>\n\n\n\n

Water Expansion Bottle<\/h3>\n\n\n\n

I’d mentioned before that I wanted to get the bracket for this bottle sorted in my mind and where it was going to go – that had led me to test fitting the bonnet and the nose cone to test that where I wanted to the expansion bottle was going to fit under the bonnet.<\/p>\n\n\n\n

So, now I have that set I drilled the holes for the rivets (no rivnuts here) and removed the cable ties that are going to get in the way. I’ll have to re-tie the cables later.<\/p>\n\n\n\n

\"Drilling<\/a>
Holes drilled for Water Expansion Bottle bracket. Aim was slightly off but near enough top of the rails<\/figcaption><\/figure>\n\n\n\n

I decided that I wanted to the rivets to sit vertically on the rails and not have to drill diagonally into the rails. That meant I had to open up the two outboard holes in the bracket. I’d set the bracket on the chassis rails so the inboard holes could be left alone, but that meant slots needed to be created in the outboard ones.<\/p>\n\n\n\n

\"Water<\/a>
Water Expansion Bottle bracket riveted in place. You can just see the elongated holes in the outboard (right) holes but the rivets are upright. The dremel slipped on the top right hole – that’ll need some hamerite later.<\/figcaption><\/figure>\n\n\n\n

Now for another conundrum… or two conundrums actually. Firstly, what orientation should the expansion bottle be. Secondly, where to route the 5\/16th” cable from the water bottle to the back of the cylinder head.<\/p>\n\n\n\n

In most of the builds I’ve seen, the water expansion bottle is placed so that the 5\/16th hose comes out directly rearwards. That means the main water hose can come out of the front-right of the bottle towards the front right chassis corner. However, while this config means the 5\/16th hose routes easily across the top of the hot side of the engine, it also means the main water hose has to bend a long way backwards to get back across the front of the engine bay.<\/p>\n\n\n\n

The other complexity here is that he build manual talks about routing the 5\/16th” hose around the front and then the cold side of the engine and then back around the back of the engine. That makes sense I guess, the primaries are going to get really hot and any water in the 5\/16th hose is going to be really really hot as it sits in that pipe. Hmmm.<\/p>\n\n\n\n

So, I decided to site the water bottle with the 5\/16th outlet pointing directly rearwards. However, I would try routing the hose as suggested in the manual… easier to do this while the hose was long rather than cutting it down and then realising I wanted it routed differently ;-).<\/p>\n\n\n\n

\"Water<\/a>
Water Expansion Bottle sited with 5\/16th” hose pointing backwards<\/figcaption><\/figure>\n\n\n\n

Now to route the hoses and see what I think of that.<\/p>\n\n\n\n

\"Five-sixteenths<\/a>
5\/16th hose wraps around front of engine<\/figcaption><\/figure>\n\n\n\n
\"Hose<\/a>
… and then into rear of cylinder head (note from the future – don’t do it this way)<\/figcaption><\/figure>\n\n\n\n

Hmmm… if using all the hose up was an objective, then I certainly achieved that.<\/p>\n\n\n\n

The other thing to add to the equation here is that I’ve seen posts and pictures of Caterham built cars where some of this 5\/16th fuel hose (it’s actually labelled as fuel hose) is used as a shroud for the braided clutch hose and also in some cases to protect the rear brake hose from abrasion too.<\/p>\n\n\n\n

Hmmm… (again)… I’m going to need to re-route this 5\/16th hose around the hot side I think and give myself some spare hose for other tasks.<\/p>\n\n\n\n

Onto something else while I ponder that one though…<\/p>\n\n\n\n

Heater Plumbing<\/h3>\n\n\n\n

Time to fit the heater… I’d had it sat loosely in the car for a couple of weeks but it was now time to figure out how the plumbing was going to work and how the heater control valve gets connected up.<\/p>\n\n\n\n

First job was to finally bolt the heater in place.<\/p>\n\n\n\n

\"Heater<\/a>
Heater bolted in and retaining bracket included.<\/figcaption><\/figure>\n\n\n\n
\"Passenger<\/a>
Passenger compartment vents installed with ears pointing downwards<\/figcaption><\/figure>\n\n\n\n

In order to get the heater pipework in I decided I needed to get more of the rest of the plumbing in place too. It was a case of “a bit here, a bit there”. Next I installed the T-piece that goes into the water inlet on the front of the engine.<\/p>\n\n\n\n

\"Blue<\/a>
Water T-piece needs a short length of hose from it to the engine block.<\/figcaption><\/figure>\n\n\n\n
\"Water<\/a>
Here’s the water T-piece installed on the LHS of the engine. The left hand pipe runs to the water expansion bottle, the right goes to the top connection on the heater control valve.<\/figcaption><\/figure>\n\n\n\n

Next up I need to work out how the J-hose runs from the back of the cylinder head (next to the 5\/16th expansion bottle hose) and connects to the lower heater control valve connection. This run of hose also needs to get cut and the water temperature (submarine) inserted inline. So… now I need to figure out where to position the submarine.<\/p>\n\n\n\n

There are lots of pictures of people installing the submarine into a Seven engine bay. The way that Caterham seem to do it now is as follows:<\/p>\n\n\n\n