Churchill Hydrolastic pump

General Chat with an emphasis on BMC Minis & Other iconic cars of the 1960's. Includes information on MK1 Action days.
Post Reply
User avatar
iain1967s
Posts: 1721
Joined: Sat Jun 10, 2017 12:46 am
Location: Cambridge, MA, USA

Re: Churchill Hydrolastic pump

Post by iain1967s »

BLT wrote: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
Posts: 514
Joined: Thu Jun 05, 2014 1:36 pm
Location: North Yorkshire

Re: Churchill Hydrolastic pump

Post by BLT »

Thanks Iain. Sounds like mine. Good idea with the plate, certainly looks the part. Cheers.
User avatar
iain1967s
Posts: 1721
Joined: Sat Jun 10, 2017 12:46 am
Location: Cambridge, MA, USA

Re: Churchill Hydrolastic pump

Post by iain1967s »

Peter Laidler wrote: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
Site Admin
Posts: 18161
Joined: Thu Jun 24, 2010 11:30 am
Location: York-ish
Contact:

Re: Churchill Hydrolastic pump

Post by mk1 »

Here's an image taken from the other thread.
You do not have the required permissions to view the files attached to this post.
Mark F
General dogsbody.
User avatar
iain1967s
Posts: 1721
Joined: Sat Jun 10, 2017 12:46 am
Location: Cambridge, MA, USA

Re: Churchill Hydrolastic pump

Post by iain1967s »

And the single hose version from the other thread
viewtopic.php?f=5&t=19836#p164565
You do not have the required permissions to view the files attached to this post.
User avatar
111Robin
Posts: 2120
Joined: Mon Dec 19, 2011 8:59 pm
Location: Aberdeen Scotland

Re: Churchill Hydrolastic pump

Post by 111Robin »

iain1967s wrote: Sun Jan 07, 2018 3:00 pm
Seamist Green 1100 wrote: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
Posts: 81
Joined: Wed Jun 17, 2015 11:33 am
Location: Gold Coast Australia

Re: Churchill Hydrolastic pump

Post by 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
User avatar
111Robin
Posts: 2120
Joined: Mon Dec 19, 2011 8:59 pm
Location: Aberdeen Scotland

Re: Churchill Hydrolastic pump

Post by 111Robin »

OGW 1082 wrote: Wed Jul 15, 2020 9:03 am 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
Posts: 81
Joined: Wed Jun 17, 2015 11:33 am
Location: Gold Coast Australia

Re: Churchill Hydrolastic pump

Post by 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
User avatar
111Robin
Posts: 2120
Joined: Mon Dec 19, 2011 8:59 pm
Location: Aberdeen Scotland

Re: Churchill Hydrolastic pump

Post by 111Robin »

OGW 1082 wrote: Wed Jul 15, 2020 10:02 am 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.
Post Reply