HOW TO .... Clear the drain holes

The MX-5 is unusual in that any water that falls on the roof makes it's way down through the car through 2 channels in order to get to the ground. It is vitally important therefore to make sure that these channels are free from any blockages if you want to avoid getting wet or listening to the water slosh up and down the sills and causing them to rust. It is a very simple task when you know how and hopefully the following guide will provide all you need to know. For clarity I've used photo's that were taken during a hood replacement but you do NOT need to remove the hood. After you've done it once the whole procedure should take no more than 5 minutes.

Firstly let me explain the route the water takes. Any water that runs off to the rear of the hood runs down over the back and into a rain rail (see photos 1 and 2 below) which directs the water to 2 holes located in front of the upper seatbelt mounting (photo 3, point A) and exits through a rubber pipe approximately ½ in diameter just forward of the rear wheel about 8 inches in.

PHOTO 1: An MX-5 rain rail.
PHOTO 2: The rain rail attached to the hood.

Any water that runs off the front of the hood gathers in that little rubber bubble you see at the top side of the A pillar (windscreen frame) and runs down the side of the door and exits through a slit in the sill at point C.


To clear the front drain hole:


Look along the bottom of the sill at point C (this will involve lying on the ground) and locate the point of the sill where the join widens for about 2. Poke this with a straightened paper clip until all the crap has been removed.


To clear the rear drain hole from above:


Peel back the carpet in the corner beside the seat belt reveal the drain hole (it is easier to see if the hood is up as the hood folds over the drain holes). Use a straightened out coat hanger to poke down the hole until the hanger reaches the ground. There may be quite a lot of resistance initially as dirt can really clog up the hole but repeated prodding will break it up. Repeat the procedure on the other side. You will be amazed by the amount of dirt under the car after doing this.

To clear the rear drain hole from below:

Lie on the ground and locate the tube at point B. Use a straightened coat hanger prod upwards to release all the dirt. You may have to squeeze the tube slightly to insert the coat hanger, as there is a flap inside it to prevent mud from the road clogging the bottom of it. Repeat the procedure on the other side.


It is a good idea to keep the hood polished as this helps keep it watertight and allows for free run-off. I use Autoglym Vinyl and Rubber care on my car (which is also useful for cleaning the interior) and they do an equivalent for mohair.