Brake pipes in the sill: corrosion, MOT failure and replacement

What runs where

Each rear line is in three parts, joined at connectors: a section under the front clam from the ABS unit, a long section through the sill, and a short section in the rear wheel arch to the flexible hose at the caliper. The sill section is held with clips and sits against the coolant pipe, with foam between. Owners talked about these using the numbers on the parts diagram (numbers 7 to 11 in the threads), but the numbering differed between posts, so check your own diagram before ordering. The clutch line runs down the passenger side in the same way.

Where it corrodes

• The rear end, where it comes out of the sill into the wheel arch, and the union there. An owner suggested water dripping from the side vent onto the pipe. In one case the corrosion ran about 18 inches up the pipe.
• Where it is cable-tied to the coolant pipe with foam between them. This was described as a classic water trap. One owner removed the cable tie on his car as a precaution.
• The front section from the ABS unit to the sill was reported as fine, "like new", in two cars.

Checking

• Take the undertrays and the rear arch liners off and look and feel along the exposed end. Clean it and check for leaks, because it may only be surface corrosion.
• A USB inspection camera was suggested for the part inside the sill.
• One owner cleaned the pipes and coated them in anti-corrosion grease while the clam was off.
• Old fluid corrodes brakes from the inside too. See brake fluid replacement.

If only the exposed rear end has gone

This is the best case. The short rear section can be replaced, or the failed length cut off and replaced with new pipe made up by a motor factor from a roll. They will give you a straight length, and you bend it to shape on the car. The flexible hoses at the calipers do not have to be changed at the same time (2012), although one owner thought it a shame to fit new sill lines and leave rusty originals.

One owner said a new end can't easily be fitted to the original steel pipe without a hydraulic press. Another said a female end can be swaged onto steel with a cheap kit, but a male end can't. This is advice from individual owners.

If the sill section has gone

A garage suggested removing both clams and cutting the sill off the chassis to run the pipes through. That is a very large job, and an owner who knows the cars doubted a sill could come off without being damaged beyond repair. Owners instead used one of these:

1. A full-length braided line. Most popular (below).
2. New hard pipe fed through the sill, joined to the old pipe at the front through the access hole under the front sill cover, or to the old pipe at the rear. The same job was done on the pipe inside the sill by cutting the old pipe at each end, threading new pipe through and making a join at each end before it enters the sill. Two owners said it is much less bad than it sounds. The risk is vibration: a hard pipe must be supported along its length or it can fracture, which is hard to do inside the sill. An owner suggested running the pipe inside a length of rubber hose or conduit.
3. Cutting into the sill from underneath to reach the pipe, and repairing the sill afterwards. One owner said he would rather avoid it.

Running the line through the cabin is possible on early Elise models but not here: an owner said the wiring loom rules it out.

Braided line the full length of the sill

• Kit and lengths. A kit sold for this job was described as replacing the hard lines through the sill, with a female connector at each end screwing onto the existing connectors. Posts quoted both a 2 m and a 3 m kit, and one owner who bought a kit just under 3 m asked the seller to confirm. One owner who had a set made up gave these figures from the rear flexible joint to the front connector under the front clam: about 250 cm for each brake line, then a further 68 cm for each line to the ABS unit. Brake lines were dash 3 with M10 x 1 fittings. The clutch line was about 293 cm, dash 3 with M12 fittings.
• Full-length custom lines. One owner ordered a full-length line from ABS to the rear wheel arch from a maker's online order form, and found the ends might not seal on the original flares. He used marker pen on the mating faces to see how well they seated, and was going to find out when he bled the brakes.
• ABS fittings. One owner said the ABS block takes two sizes of fitting: M14 on the passenger side and M10 on the driver side. Another said he thought so. Treat as unconfirmed.
• Heat. The coolant pipe next to the sill run is hot (one owner quoted 90°C), and the braided line rests against it in places. Cover the line in heat sleeve through the sill. Some kits come with part of it covered. Padding when tying it to the coolant pipe was asked about, but not answered.

Routing it

1. Remove the rear arch liner and the sill cover on the side you are working on. The front access under the sill cover is on both sides (see plastic sill cover removal). On a Turbo the intercooler can block access to the sill from the wheel arch, and one owner got in by taking off the rear arch "ear", whose fixings were spinning.
2. The foam packing around the pipes in the sill is not tight, and a line can be pushed along. One owner's tip: slip the new line inside electrical conduit or a length of silicone hose, push that along the sill, pull the line a little further out at the front, tie it off and remove the conduit. A long rod was also used to get through the packing.
3. At the front, the line goes through the dash corner and a small hole into the bonnet area. The driver's side needs the dash top off to follow the route (see the dash pictures in the thread, which are not reproduced here). One owner got both lines through the existing hole at once, the other found the grommet would not move and drilled a new hole in the black ABS plastic cover with a stepped drill bit.
4. Fit the new lines alongside the old ones before disconnecting anything, then swap the connections quickly. Afterwards cut the old hard lines into pieces and pull them out through the access points. One owner blew through the old line into a container to catch the fluid in it.
5. Tie or clip the new line along its route. One owner used flexible-hose P-clips, and another suggested fir-tree cable ties in the old clip holes in the subframe.

Swapping the connections

One owner's sequence, which avoided air in the system and needed no bleeding. Another owner advised the same order: start at the rear and work forward, and connect the new line at the front first, because fluid then heads towards the rear and gives you time to connect there.

1. Loosen the front and rear connectors, and unclip the old hard lines near them. Remove the clip that sits where the new line must go, before you undo the line. Line the area with absorbent towel and fit a blanking plug to the caliper end of the new line.
2. Undo the rear connector (13 mm) and bend the old line down to start draining.
3. Undo the front connector (13 mm union, 11 mm nut at the ABS side) and move the old line out of the way.
4. Connect the new line (12 mm) to the existing hard pipe at the front. This took two people, one on each side of the connection.
5. Take the reservoir cap off so fluid flows through the new line, and watch the level so it does not drop below minimum.
6. As soon as fluid is flowing, connect the new line at the rear.

Don't pre-fill the new line with fluid (one owner's advice). The old rear connection can be rusted, so check it can be undone first. If the system does empty, bleeding is hard because air gets trapped in the calipers. A vacuum bleeder worked for one owner. Another prefers a pressure bleeder at no more than 12 to 15 psi. They disagree, and neither is checked. The owner who did it with no air also said bleeding is not needed if you manage the swap as above.

Owners also noted the flexible hoses at the calipers can be replaced with braided ones while you are there. For the front hard lines from the ABS unit and master cylinder, an owner said Europa part numbers beginning A116, B116 or C116 are normally the same as the VX220 ones, and that the pipes are made straight and meant to be bent, so a slightly bent one is often fine.

Flexible hoses only

If an MOT fail says "brake hose" it is worth checking which part the garage means. A cracked flexible hose at a wheel is a simple job. One owner said garages charge about £40 to £80 per hose (2015), and the rear is very easy and the front easy with patience. A tip for the hose swap: fit the hose to the pipe and let it fill until it drips, then fit it to the caliper, which saves pushing air through. If it is "the one that runs the whole length of the car", it is the hard line in the sill.