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Carrying on with the ‘will it go again?’ Theme of my cars restoration, I want to try to reuse the radiator it ran before I took it off the road some twenty five years ago. It didn’t leak back then but who knows now..

I’d thought about putting a cap on, stopping the bottom hose up, filling it with boiling water and pressurising it using a cut of bicycle inner tube over the top hose.

Has anyone tried this before and what did you use to bung up the unused outlet? I’m thinking of something like a bypass hose blanking pipe but larger?

Also, in the event it does test ok with no leaks, what’s a good way of flushing and descaling it?

I haven't done this before but I'm sure that there is a descaling liquid chemical that you can put into the rad to de-fur it while it's outside. As for testing it for leaks, then this is what I have done. Don't forget that it will pressurise to the pressure of the rad cap. Given that your household water pressure is approx 14psi, then in theory, that should exceed the pressure of your rad and cap. So block up the bottom hose (or the radcap) and put a garden hose into the bottom, make sure it's sealed and turn it on full tilt! If the rad is leaking, you'll see it. Test the heater rad while you're there too!

I just left mine pressurised at household mains pressure overnight and it was still holding the next morning, so I put it back

But I'll let you into a little secret. If the rad is OK and not leaking, put it back and instead of using water and anti freeze, use EVANS waterless coolant. It doesn't pressurise the system so you won't have to worry about split hoses ever again. Thereafter, the radcap isn't a pressure cap as such but just a cap to keep the liquid in!

I use an old bicycle inner tube...cut it about 15 inches on either side of the valve....clamp one end to the top outlet and the other to the bottom outlet....fill with water...replace the cap and then pump in a few pounds of air....seems to work well.

That's a bluddy good idea Dermot!

Agreed that is a bloody good idea and was thinking of how I could test the radiator on my Unipower which has done minimal mileage before being taken off and stored the best part of 50+ years ago.
It looks really solid but you just never know.
So that’s the plan for later then.

Does a new recored radiator out perform a 50myear old one though?

Peter Laidler wrote: ↑Mon Apr 19, 2021 3:39 pm That's a bluddy good idea Dermot!

Thank ya thank ya... thank ya vaary muuuch!!!

360gts wrote: ↑Mon Apr 19, 2021 3:31 pm I use an old bicycle inner tube...cut it about 15 inches on either side of the valve....clamp one end to the top outlet and the other to the bottom outlet....fill with water...replace the cap and then pump in a few pounds of air....seems to work well.

That’s such a simple and brilliant idea

Aginley wrote: ↑Mon Apr 19, 2021 4:31 pm Does a new recored radiator out perform a 50myear old one though?

Quite probably but if you saw the size of the Unipower Radiator for a 998 engine car, I'd be surprised if the car would ever get warm once it was moving.
Saying that the radiator is in the front and a very hot engine in the back so will have to make sure the water pump is working well.

Have had to check a few radiators and have left them pressurised overnight. If they are OK in the morning then it proves only one thing, that they are currently airtight.
Surely a bike inner tube will just expand in diameter and so reduce any pressure in the system?
If there is not a pressure gauge in the circuit then I would say you can only guess at the pressure it can cope with.

Actually that's a good thought.
Most stirrup pumps have a gauge on them and think you would only be looking at 10-15lb tops for the pressure in the radiator.
but then would need to see how much the tube expands in the process.
Or a big rubber bung with a valve in the end of one of them and make sure that they are fixed with enough tape around to stop them flying out at great speed.

Well, backyard testing is inconclusive and frankly I trust neither of these. Will look at a recore - I presume the flat top Coventry one is more appropriate for a November 61 850?

I made plugs from some 1/2" heater hose. I cut 2 short pieces (for 2 plugs) about 30 mm long and then put an M12 bolt with washers through it and a nut. These are then inserted in to the outlets and the nut nipped up, causing the hose to expanding the hose and bingo, they are sealed.

These days, I have a cooling system test kit, that has a small hand pump, with a gauge and various dummy caps that the pump plugs in to. Before I had that, I used a Hand Tyre Pump and clipped the chuck on to the overflow outlet, using a blanking cap (from the ADO16) to cap off the radiator.

Pump it up to 18 PSI, put it in a tub of water and look for air bubbles.

You can use CLR to clean them (Hardware stores may have it), but depending on what condition the cooling jacket of the engine was in, it may need the tanks removed and mechanically cleaned before any chemical clean will work effectively.

Surely a bike inner tube will just expand in diameter and so reduce any pressure in the system?

It is the law of physics....of course the inner tube will expand.....who cares!!! You can inflate to 11-15 lbs....it doesn't matter how much the inner tube expands...the pressure is constant...........that is the law of physics!

You can measure the pressure easily with a gauge.

I made good experience with citric acide.

Had my engine full of rusty water...

Flushed it with clear water, then put some 100g of acide in the system and let run the engine hot for about 30min.

Then flushed again and did this procedure 2 more times.

In the end the cooling fluid is still clear blue after some 2000km now.

Take some time, but worth the effort.

I think the Engine itself also Profit from this

Just when I was thinking of pulling my hair out, Dermot has come to the rescue. Thanks Dermot and Spider too. Or just use household pressure of 14psi. You only need to test it to the pressure it's going to get to. As for getting a re-core when it ain't leakin'....... IT AIN'T LEAKING.....

Just make sure to de-scale (i.e. with citric acid = coffee machine de-scaler) before you pressure test. The scale might just plug the hole that appears after de-scaling.

• put it into a thick walled, 70 -100cm long radiator hose.
• valve fed through a radially drilled hole towards the end of this rad hose
• inner tube with rad hose attached and clamped to radiator.
• Fill radiator and hoses with water (add a few drops of luminescent fluid for UV-leak detection)
• Pressurise rad to not more than 1.2ish bar (~17psi) using compressed air.
• Checkfor leaks with UV-light.

360gts wrote: ↑Mon Apr 19, 2021 10:10 pm Surely a bike inner tube will just expand in diameter and so reduce any pressure in the system?

It is the law of physics....of course the inner tube will expand.....who cares!!! You can inflate to 11-15 lbs....it doesn't matter how much the inner tube expands...the pressure is constant...........that is the law of physics!

You can measure the pressure easily with a gauge.

Well I am never one to argue with the old law of physics!
And maybe once you have pressurised your system and your pipe expands overnight then the system pressure will remain constant, I can't possibly say. Unless of course there is a gauge in the system to show you what is going on as you cleverly suggested, and a very clever suggestion it is too!

PS. you have the radiator out and it is 25 years old so maybe now is a better time to get it recored rather than fit it and have to take it out in the possibly near future?
It may be bunged up with radweld/silt/ scale, and it is doubtful that no part of it is blocked.
Every car build/restoration I have done, I have upgraded the matrix with an extra core.
I have had enough of sitting in Bank holiday traffic with my fingers crossed and the heater on full!

Bitsilly wrote: ↑Tue Apr 20, 2021 6:47 pm PS. you have the radiator out and it is 25 years old so maybe now is a better time to get it recored rather than fit it and have to take it out in the possibly near future?
It may be bunged up with radweld/silt/ scale, and it is doubtful that no part of it is blocked.
Every car build/restoration I have done, I have upgraded the matrix with an extra core.
I have had enough of sitting in Bank holiday traffic with my fingers crossed and the heater on full!

Your heater works..?