Any tips for using a 'churchie' to pump up the hydro?

[AndyPen]

I've two cars that need a decent pump and would like to purge them first.

The instructions on my churchill 'dalek' seem simple enough but the last time I did this must have been in the early 90s and even then, it was probably just a pump up.

Any tips and tricks I should be aware of?

[iain1967s]

Personally, I wouldn’t worry too much about using the vacuum side of the pump. Multiple pressurize and release cycles are usually good enough to purge the worst of the crap.

Even though it has the capability, I don’t do the drain down via the pump unless I’m dismantling the suspension. If you do, your nice clean fluid in the reservoir will turn to sludge as all the old sewage gets pumped out...

Use Peter’s handy dandy ‘rod through a piece of hose’ trick [technical howto section of the forum] to dump the old stuff out into a tub/bowl instead.

Scragging the car is also useful to get the bags to settle evenly, especially if the system has been left dry or was drained down for disassembly so might have trapped air.

Oh, and there’s nothing really special about hydrolasic fluid. It’s just 50:50 mix of distilled water and anti-freeze, so any cheap green non-organic premixed engine coolant can do the job just as well.

Never use oil based suspension fluid.

[OGW 1082]

Andy
Can I just add don't forget to protect your eyes. Old things can burst and unfortunately your head can be down amongst it all.

Glen

[AndyPen]

Andy
Can I just add don't forget to protect your eyes. Old things can burst and unfortunately your head can be down amongst it all.

Glen

Very good point Glen - I shall be sure to do so.

I'll go and look for that article Iain

[Aussie Bill B]

I have modified my pump to empty the drained fluid into a container under the pump and not into the new fluid in the main tank. You could drain the dirty fluid into an empty main tank before filling it with clean fluid for a pump up.

Just drain and flush a few times to get the worst out.

The hydrolastic fluid was not just anti-freeze and water. That will work to protect the metal internals but the original fluid formula had additives to stabilise expansion and contraction of volume with temperature changes as well as additives for "lubricity" to lubricate the valves, as early systems sometimes had a squeak.

[AndyPen]

I have modified my pump to empty the drained fluid into a container under the pump and not into the new fluid in the main tank. You could drain the dirty fluid into an empty main tank before filling it with clean fluid for a pump up.

Just drain and flush a few times to get the worst out.

The hydrolastic fluid was not just anti-freeze and water. That will work to protect the metal internals but the original fluid formula had additives to stabilise expansion and contraction of volume with temperature changes as well as additives for "lubricity" to lubricate the valves, as early systems sometimes had a squeak.

The tank is empty as it happens, so good point to do that on both cars first - thanks