What size is 2006 Ford Focus rear drum brake bleeder valve?

I replaced a brake cylinder on my 2006 Focus rear drum brake. Now, I need to bleed the brake fluid, but I can’t find a wrench to fit the nut.
10mm is too small and 11mm is too big. What’s going on? Could it be the rusted nut has grown in size enough to make the 10mm wrench too small? Or, is the nut standard?
I know the drum bleeder nut I know the front disc brake bleeder brake is 10mm. So, I am thinking the rear should be metric, but since it’s drum, I am not so sure.
Has anyone done the rear drum bleed and remember what the size is?

Thank you.

10mm and 11mm are very close to 3/8".

So try a 3/8" wrench.


My 40+ year old drum-brake-equipped Ford truck requires a 3/8 " bleeder wrench. I would have guessed Ford would have switched to a metric size bleed screw by now, but maybe not. Are most all the other bolts in the 2006 Focus metric?

Most nuts are metric, but this is a drum brake, so I am thinking they may have stayed with standard. 3/8" comes to 9.525mm. ((3/8)*25.4mm=9.525mm). 10mm wouldn’t fit.

I have no difficulty buying brake wheel cylinders for my truck, always in stock every time I need one. So maybe they’re just using the same wheel cylinder design they’ve used for 40+ years. I guess if it works, no particular reason to change it.

How can the nut be rusted if it’s a new wheel cylinder?

I may be wrong but if you are doing work on brakes and something was rusted would you not just use vise grips and replace it while you are there ?

I agree with @asemaster but also I question why some one would work on their brakes with out having the tools to do so. I mean there are only a few possibilities just keep trying both metric and sae sizes until something fits. If you can’t get anything to fit something is very wrong.

How can the nut be rusted if it's a new wheel cylinder?
@asemaster ... maybe the OP means they replaced one wheel cylinder, then needed to bleed the entire system.

The bleeder port is 10mm diameter and the hex appears to be larger in the parts store photo.

I would guess that it’s 12mm.

Interesting. The inlet port is spec’d as 10 mm. That seems like it implies metric threads all around for that part, so the wrench that fits the bleeder screw would be a metric size too. I wonder why whoever input the information for the part didn’t just spec the dimensions for all the holes in the darn thing instead of just for the input port? Anyway, maybe the OP is correct, the bleeder screw he was having trouble with was on an existing cylinder, and rusted or someone before him had manhandled it in a prior bleeding operation, rounding it off and reducing its size. I’ve done that same thing attempting to remove a bleeder screw rusted in place. I’ve had to replace the entire wheel cylinder to give me a working bleeder screw on at least one occasion.

Ah, the wonderful world of brakes. Isn’t brake fluid fun to work with? … NOT! … lol …

The input and bleeder ports are interchangeable. The same wheel cylinder fits the left and right wheel.

In my opinion, if one wheel cylinder is leaking, it makes sense to do both.

it would be stupid if he went to all the trouble of bleeding the brakes, and next week, the other side fails and contaminates the brake shoes

it would be stupid if he went to all the trouble of bleeding the brakes, and next week, the other side fails and contaminates the brake shoes

But then again the OP is having trouble even finding which wrench will fit.