Churchill Hydrolastic pump

[iain1967s]

Can anyone tell me if the neck of their tank where the cap goes has thread all the way round, like a regular jerry can, or if it's just a couple of short lengths like mine? Thanks

The original tank on my pump looks to be blow molded from two halves, each tank half has one 180° thread on the neck, tapered in for about the first 45° on each.

[BLT]

Thanks Iain. Sounds like mine. Good idea with the plate, certainly looks the part. Cheers.

[iain1967s]

That's a brilliant job Iain and I've been following your progress. I wonder why you don't do one of those singular '....this is how to do it' threads for the technical talk bit of the forum.

Hi Peter. I don’t think I am up to writing a technical how-to, but I did a high level write-up for our local club newsletter and I’ll probably re-post that to the general forum at some point.

[mk1]

Here's an image taken from the other thread.

[iain1967s]

And the single hose version from the other thread
viewtopic.php?f=5&t=19836#p164565

[111Robin]

Sometghing I discovered on my pump was the vacuum Schrader chuck is a Turner "Renrut" chuck off a Kismet foot pump.

Yeah, I've been tracking a few of those on eBay. Trouble is the pumps are also collectors items so it gets expensive real quick...

A modern alternative is to use the couplers used for refilling nitrogen in aircraft landing gear struts. There are two designs available, one with a 1/8" male and one female. Both have separate Schrader thread clamps and screw-in pin depressors, which is the whole point of the original adaptors on both sides of the pump. Obviously if you have a single line pump you only need one of these - they aren't too cheap...

Note that the thread clamp on these strut couplers uses a copper washer to seal against the top of the Schrader stem, so it will need tightening down with a spanner to seal properly, not just finger tight as with the original coupler. I might try using a small O ring instead of the copper washer.

The male version plus a 1/4" to 1/8" reducer seems to fit well for the pressure side of the pump. Note: It feels like it will screw directly on to the thread of the bleed screw even though one side is NPT and the other is BSP, but if you want to do it properly use a thread converter.

I haven't tried it but I think the female version with a 1/8" NPT to a hose barb would be a good replacement for the renrut on the vacuum side, since that connects directly to the 5/16 ID hose rather than to a screw coupling.

Here is a photo with the assembled pressure side, this is just hand tightened using plumbing PTFE tape as I don't have the NPT to BSP thread converter yet - waiting for delivery. Amazon numbers for the parts I used so far are below.

For pressure side:

Stainless strut valve no-loss coupler 1/8" NPT male
https://www.amazon.com/gp/product/B005VR4M88

Brass 1/4" NPT female to 1/8" NPT female adapter
https://www.amazon.com/gp/product/B013RWMGAY

Brass 1/4" BSP female to 1/4" NPT male converter
https://www.amazon.com/gp/product/B015ROAYWC

For vacuum side:

Stainless strut valve no-loss coupler 1/8" NPT Female
https://www.amazon.com/gp/product/B00JJND6AK

Stainless 1/8" male to 5/16" ID barb (5pk)
https://www.amazon.com/gp/product/B017N4U13Q

I've started to attempt a resurrection of the pump I rescued from a skip. It's missing the T bar bleed valve, has anyone been able to source one ?. I haven't searched yet, just wondering if there's already an identified source ?.

[OGW 1082]

Hello all,
I'm not sure if this will help anyone here, but I've recently overhauled my hydro pump
The one I have is the Australian version Austaloy 18 G 703 but looks the same as the Churchill one
It took a while to source suitable seals but eventually I found some that worked.
They were Hallite seals.
Pressure Pump - Product Group - 511 Part# 8806510
Vacuum Pump - Product Group - 58. Part# 6504850
Both functions of the pump work properly.
Regards,
Glen

[111Robin]

Hello all,
I'm not sure if this will help anyone here, but I've recently overhauled my hydro pump
The one I have is the Australian version Austaloy 18 G 703 but looks the same as the Churchill one
It took a while to source suitable seals but eventually I found some that worked.
They were Hallite seals.
Pressure Pump - Product Group - 511 Part# 8806510
Vacuum Pump - Product Group - 58. Part# 6504850
Both functions of the pump work properly.
Regards,
Glen

Thanks Glen, I'm overhauling a UK 18G703 just now so this is useful info'. I'm missing the bleed valve that fits infront of the low loss valve though, I'd like to fit the same part not an aternative of which I know there are plenty to choose from.

[OGW 1082]

Sorry I can't help with the bleed fitting.
If you want some good reading, google" Hydrolastic/Hydragas Repair" by Mark Paget
It covers everything one would need to know and probably more.
Glen

[111Robin]

Sorry I can't help with the bleed fitting.
If you want some good reading, google" Hydrolastic/Hydragas Repair" by Mark Paget
It covers everything one would need to know and probably more.
Glen

Yes thanks, I have read this, good source. Ref. the pressure pump seals, does it require 2x the part number you quoted ?. I haven't stripped mine yet as it is still working although I can't build and hold pressure so the fluid might be passing the pump seals, although there is no fluid coming from the pump body past the plunger which is odd. There are no other external leaks so I'm trying to figure out where I'm losing pressure. Possibly the non return valve as this would just leak back into the tank so wouldn't be seen externally.
Thanks.

[850man]

I have owned and repaired a heap of churchill & austaloy pumps. At one point I owned 6 of them, I am now down to a restored Churchill and a unrestored Austaloy. The former Mini specialist business I worked for had at least 20, back in the 90s you could buy them for next to nothing, and almost every garage/service station had one here.
I had the Churchill ID plates remade a few years ago, along with the instruction plates. The traffolyte label company I used to get them made has now gone out of business so I have not bothered to have any more done.
A chemist friend supplied the ingredients to make proper Hydro fluid as well.
Tony Cripps here in Australia was making up repair kits for them & selling on Ebay for awhile, I think he sold his last one recently and a well know Mark on this forum ended up with it with some help from a couple of Aussie friends.
I have always been able to repair them usually with minimal parts, they often only require a decent clean/flush out. The plastic hose is available from any hydraulic supplier, and the square section seal in the fitting on the ends of the hose is found easily.
I even had a couple of the plastic caps 3D printed.
Aussie pumps had either Smiths or Floyd gauges, Floyd is still in business and can repair original gauges or supply the modern equivalents.

I have 100s of photos but its a pita to reduce the size of them so I cant add them here.

[111Robin]

Good to know there's a wealth of experience on these units, thanks. First question I have is regarding the flow restrictors on the vacuum pump inlet and outlet. I wasn't aware of these when I was removing the pump but found one lying on the ground. These are the thin hexagonal buttons that fit inside the female ports. I take it there are no additional parts that might have gone missing ?. No springs or balls or anything like that ?. So presume it's just a case of placing the restrictor into the female port before making up the union, same on inlet and outlet ?.

[OGW 1082]

No Robin, no ball or springs in that part you are correct.
Glen

[111Robin]

No Robin, no ball or springs in that part you are correct.
Glen

Thanks Glen, saves me crawling around the garage floor looking for missing parts

[111Robin]

My pressure gauge sits at 100psi with no pressure applied. It does respond to applied pressure and isn't leaking. If I press inwards on the bourdon tube the needle moves back to zero but just springs back when I let it go. Perhaps it has jumped a tooth or two on the gear mechanism ?. I can't get the needle off to enable the face to be removed to gain access to the mechanism, I'm assuming a special puller is required?. Any ideas ?. I don't really want to replace it. It's a Smith's instrument.

20200714_150904 by Robin Derrick, on Flickr

[mk1]

All fascinating stuff!

Mine is still waiting for me to get round to sorting it out. It will still pump but its vacuum side sucks (but not in a good way).

[iain1967s]

Illustrated parts list for the two hose pump
[ extract from http://mk1-performance-conversions.co.u ... -sti-g.pdf ]

[Peter Laidler]

I've been making my own hydro pump on-and-off over the past couple of months. I have used an old pressurised fire extinguisher as the vacuum reserve and catch tank and ordinary plumbing isolating valves as the a) hold the system vacuum and b) release the new fluid into the system valves.

The only drawback so far - which I see as an absolute ADVANTAGE - is that you cannot use the old/drained fluid to replenish the system. You have to use new or previously cleaned and filtered hydro fluid

Moulton and Churchill certainly knew how to complicate things, believe me!

The BEST bit is that it works perfectly, so far*, AND THE COST SO FAR HAS BEEN ABOUT £10
* needs a new vacuum pump as experimental pump doesn't have a gauge

Anyone interested in the details/pictures when it's finished in a couple of weeks?

[spoon.450]

Sounds interesting Peter, and it would be good to see pics and details when finished.

[Andrew1967]

Just collected a Churchill 'Dalek' that I bought last year on eBay. Apart from a repair to the pressurising pipe, it looks pretty good and appears to work.

The instruction plate is somewhat past it so I'd like to find a replacement.

I know these have been remade in the past and was hoping someone had one left over waiting for a good home