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PostPosted: Sun Dec 03, 2017 6:26 am 
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iain1967s wrote:
The old tank is made of some kind of olefin plastic, but of course it pre-dates the introduction of material content labeling regulations so no markings to work from...

I tried for different epoxies to fix the cracks in the old tank. JB Weld Plastic Bonder seems to be the only one which will bond.

I also found a similar tank from US Plastic, part number 8819 if anyone else needs similar. It’s 5 US quarts, so around one imperial gallon. Less than the original, but unless you’re running a 1960s BMC dealership I doubt that will be a limitation.


Great stuff!

I will keep the US plastic tank in mind.
I have an Australian Austaloy pump which is the local copy of the Churchill. They have a soldered metal tank in place of the plastic tank. Mine was rusty as heck so I soldered all the holes and painted the inside with epoxy. I don't think it will last forever.


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PostPosted: Wed Dec 13, 2017 8:28 pm 
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I've a mate who collects Churchill hydrolastic pumps :lol: I bought one of him on Monday and he went immediately to view another one he knew was for sale :lol:

I remember being told some years ago that when hydrolastic cars first appeared in 1962 only BMC dealerships had hydrolastic pumps, would that be correct?

Alan


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PostPosted: Thu Dec 14, 2017 2:59 am 
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iain1967s wrote:
For the custom seals on the pump pistons that are NLA, the originals will need to be reused. Classic motorcycle restorers rejuvenate rubber parts by a week's soaking in rubbing alcohol + wintergreen oil mix (3:1 ratio). I've never tried that but it's worth a shot.


Update 13 Dec:
I've had the seals soaking in that mixture for a couple of weeks, and the rubber definitely seems to have softened up and swelled a little. I am going to reassemble both of the pumps at the weekend, and see if they will hold pressure and vacuum.

Update 18 Dec:
The special two-part shaped seal in the pressure pump is held in place by a rubber cone reinforced with fiber. These all seem to have recovered well with their soaking in the mixture, and now seal correctly when reinstalled in the pump. See bottom photo of the reassembled pressure pump before the front plate is re-fitted.

The plain seal between the vacuum pump piston and bore did not fare so well. Although the rubber swelled up and softened in the mixture, it does not have any fiber reinforcement to hold it in shape. The result was a seal that swelled well beyond the correct 1.5" outside diameter, and it broke up when I tried to compress it back into the bore.

So now I am looking to replace the vacuum seal with a modern hydraulic type. I've ordered a few different sizes off eBay to see what fits best. Will post the results back to this thread once I get it figured out.

Update 27 Dec:
I found a modern hydraulic seal which fits perfectly. It's listed as "Hydraulic Rod/Piston Seals 1/4"CS x 1"ID x 3/8"HT Type" and is MFP Seals part number XP-250-01.000-375BU2145, the yellow,part in the attached photo.

The original vacuum seal consists of three layers : a fiber spacer, the broken rubber seal, and another fiber spacer, all sandwiched together under compression by a brass plate and nut.

The new seal is not quite wide enough to replace all three of the original parts, so I used a plain Neoprene 1.5"x1"x1/16" washer (E15010116) against the open face of the new seal, so that the brass plate and nut have something to compress against.

For anyone else who needs to do this in future, the assembly order is: shaft, brass piston, neoprene washer, hydraulic seal (open face inwards), brass plate, nut.

Now I have two working pistons, time to reassemble the whole unit and check it actually works.


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Last edited by iain1967s on Wed Dec 27, 2017 2:34 pm, edited 5 times in total.

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PostPosted: Thu Dec 14, 2017 9:17 am 
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I remember being told some years ago that when hydrolastic cars first appeared in 1962 only BMC dealerships had hydrolastic pumps, would that be correct?

I am sure that would have been the case. They weren't a cheap bit of kit either.

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PostPosted: Fri Dec 22, 2017 1:53 pm 
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Anyone know where I can get a cap to fit the resevoir on top? Either an orginal if anyone has a 'spare', or some other type that might fit. Seems to be around 2" across and very course thread, not sure if it needs a perfect seal. Was looking at item 301663237424 on eBay, it's an IBC blanking cap for those big water tanks, but doesn't look deep enough. Any ideas? Thanks.


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PostPosted: Fri Dec 22, 2017 2:02 pm 
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I'm sure one from a plastic jerry can will fit

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PostPosted: Fri Dec 22, 2017 2:11 pm 
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That's what I thought but can't find one big enough.


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PostPosted: Thu Dec 28, 2017 5:03 am 
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BLT wrote:
Seems to be around 2" across and very course thread, not sure if it needs a perfect seal.


I think the cap is just to stop dirt getting in, to protect against spills when moving the pump, and to reduce evaporation of the fluid in the tank during storage.

It does not seem to provide any kind of pressure seal, in fact mine has a 1/8" vent hole at the top to allow air in to / out of the tank so it doesn't either collapse or inflate when the pumps are used.

Not sure where you could get a replacement, but the thread looks similar to that on a petrol lawn mower or other small engine such as a snow blower or go-kart.


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PostPosted: Thu Dec 28, 2017 6:19 pm 
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Well, here is the end result of my pump restoration. The new seal holds a vacuum against my finger on the Schrader, and nothing seems to be leaking out after I half filed the tank with 5 liters of green 50:50 antifreeze premix.

The pressure side still isn't working properly yet - the piston was pumping air OK before I filled the tank, but the handle is now very hard to push down since the pump was primed with fluid. I think I might have put the outlet one-way valve in backwards. Should have taken more photos during disassembly.

Note: I replaced all 15 Dowty washers with new (1/4" BSP) when reassembling, and I decided to use the repaired original tank rather than the new one.

Because of the epoxy repair to the bottom of the tank I used O-rings on both sides of the bottom outlet to give a more flexible seal with less stress on the tank than the original plastic washers.

ps. Yes, I know the white and black arms are the wrong way around, pressure should be black, vacuum should be white. It was like that when I got it, but the arms are seized on the threads currently. I didn't want to force it...


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PostPosted: Thu Dec 28, 2017 8:13 pm 
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That's a brilliant job Iain and I've been following your progress, learning on the way. I'd like to do one one day just for interests sake really. I wonder why you don't do one of those singular '....this is how to do it' threads for the RELATED TO thinggy on the technical talk bit of the forum. There must be plenty of these old cabinets sat unused and rusty. Just wish thge owners would sell them on. To be honest, seeing your progress, it must be worth taking a punt on an old knackered one for a rebuild project!. Great work


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