Power Steering Fluid Leak

Yes, my petrol 1.6 mark 2 focus needed the power steering hoses replacing at about 10 years old; dealer-only parts. I looked at the difficult manouevering around the air con pipes and left it to a local mechanic.

I have seen this on coolant header tanks where the leak is from a crack around the plastic spigot of the reservoir, not the hose at all.

In message , andrew reeve writes

I don't know if it's relevant, but my Mk1 Focus power steering suddenly sprang a leak. The local garage was able to fix it. They said there is a pressure switch which senses when that steering is being applied, and this tells the electronics to speed up (or at least maintain) the engine revs. It was the switch that was leaking, and it didn't cost too much to have it replaced.

I have seen that several times, I soldered up one of those switches, there was never a problem with stalling, but they do leak under quite a bit of pressure so that leaking will empty the system very quickly.

Purely out of interest, soft solder or silver solder?

(I?m assuming you solder to seal the leak rather than an electrical connection.)

Just soft solder, take out the sensor from the pump, remove the broken up switch part, lightly drill through the body, drop in a brass screw and solder it with a gas torch. Lasts for ever.

Thank you.

As I say, I was just curious. Often silver solder is used in pressurised systems although I?m not suggesting you method isn?t safe etc. I don?t know the pressure in the system.

I would hazard a guess at a max of 100 psi, they would have leaks everywhere if it was really high.

I had to replace my Fiesta coolant tank a few years ago. Apparently it's common for them to become brittle with age, and for cracks to appear. My other reservoirs seem okay so far, but if they are from the same source (and I've no idea if they are), it's probably a good idea to check them from time to time. Although I expect the coolant tank is more susceptible, if it is subjected to positive pressure.

With standard plumbing coupling geometry, a good soft solder joint should be stronger than the copper pipe.

Don?t know what pressure you start to need silver solder. They use it on fridges, I believe, on the cooling side.

Well it is really high! 10 times higher than your guess.

My power steering test spec says 995 psi on HP pump to rack line engine idling.

Test kit is pressure gauge and a shut off valve, fits in HP line at pump.

1: fit tool, open shut off valve, bleed air from system, top up fluid. 2: Run engine, make sure fluid temp rises to 60 to 80 °C (140 to 176 °F) 3: check pressure with steering in fully left and right positions, engine idling at 1000 rpm.

Do not hold in fully locked position for more than 15 seconds. Standard pressure 6,865 kPa (68.6 bar, 70 Kg/cm², 995 psi)

4: If pressure below standard pressure slowly close shut off valve observing pressure. If pressure reaches standard pressure gear is damaged. (it's pissing fluid past seals) If pressure does not reach standard pressure pump is damaged (pump vanes or body worn).

CAUTION do not close shut off valve for more than 15 secs (fluid temp will suffer excessive rise).

5: If pressure in excess of standard pressure pump is damaged (relief valve stuck shut). 6: remove tool, add fluid, bleed air from system.

Yes, I have used it on air con, I had been told that it was because there was no need for a flux, which would contaminate, but that was not a really good source of info. Air con runs up to about 300 psi or so.

I vaguely remember a rule of thumb for car a/c : the high pressure side should be 2 x temp in F + 50 PSI.

I suspect it is no more than a crude guide.