Even before my girlfriend and I met, she's been dealing with a constant coolant leak in her car. Being that she doesn't know the first thing about them, she assumed it was a huge problem that would cost thousands of dollars to address and decided to just continue adding coolant every few days. Turns out, this coolant leak is a very common issue on the Ford Focus, and while she was quoted $500 for a repair, it wasn't too difficult for me to do for her in my own garage.
The main reason I'm writing this up is to clarify a few points on the great writeup I used as a basis for going about the job. Hopefully Google will index this page and it will be helpful for those later searching for tips.
First, you'll want to read over the writeup here: Replacing the thermostat and/or thermostat housing (Ford Focus). Parts were easily obtained by contacting Steve of Tousley Ford on the FocalJet Forums. His username there is "FORDSVTPARTS". Of course you also have the option of ordering the parts from your local dealer, though they may charge a bit more.
•Your coolant draincock may vary from the one pictured. In her car it was a black plastic screw with no way to attach a hose. Be careful as you turn the screw: it will go from a slight dribble to a powerful spray in a moment's notice! I ended up with a face and mouth full of coolant when it sprayed out unexpectedly.
•In step 8, the rear hose is a real P.I.T.A. to remove. I can't believe the author of the how-to didn't expand on that,.. but seriously.. it sucks! I used a combination of 2 different pairs of pliers, a vice grip, and 2 different length screwdrivers to remove it. After much failure at trying to simply squeeze the clip(due to it's position facing towards the battery), I changed my strategy: I used the screw drivers to pry up the tabbed side of the clip and spun it around to a better position. *Then* I was able to grab it with pliers and remove it. In order to give myself some more flexibility to move and angle the housing while I worked, I temporarily disconnected the bottom-most hose from the radiator side *first*.
•Putting everything back together is much easier.. you have better access to the clips to position them how you want. Obviously you'll want to spin them around to the tops of the hoses before you attach them to the new thermostat housing.
All in all, this took a couple hours and a few small cuts but it wasn't too difficult at all. Instead of a $500 repair bill, my girlfriend made out at about $100 including the parts($55), new antifreeze($9), and a nice steak dinner for me. Everybody wins.
