How to (not) repair a radiator ...

[crypto]

After putting my rebuilt engine and all the other things back into the car, I noticed she was loosing water. The source of the misery was the radiator. At the time the rad was out, I poured some descaling agent into it, to clean the thing in and out.

Just a little pressure, and air was coming out all around.


This rad had a really bad life, as some of the previous owners must have filled it up with tap water which got frozen and cracked the thing. I repaired all the hairline cracks in the brass and got it up to 30psi, then it startet leaking from the thin tubes. Now its waste, anyone got a spare alloy rad for sale ?

[TimJM]

I don't have an alloy rad but I was thinking about your test. Aren't radiator caps generally 1 bar so 14psi max? Would putting 30psi into the rad cause any damage?

[Jhonno]

TimJM said:

I don't have an alloy rad but I was thinking about your test. Aren't radiator caps generally 1 bar so 14psi max? Would putting 30psi into the rad cause any damage?

2-3 bar iirc... 1 bar is atmospheric.

[TimJM]

Jhonno said:

2-3 bar iirc... 1 bar is atmospheric.

Are you taking about absolute pressure as I always assumed gauge/tolerance measurements to be zero based not one based in regards to atmospheric pressure.

[Jhonno]

TimJM said:

Jhonno said:

2-3 bar iirc... 1 bar is atmospheric.

Are you taking about absolute pressure as I always assumed gauge/tolerance measurements to be zero based not one based in regards to atmospheric pressure.

Doesn't matter, at 1 bar the coolant would still be boiling @100 degrees..

[TimJM]

Jhonno said:

Doesn't matter, at 1 bar the coolant would still be boiling @100 degrees..

Now I am getting more confused...

If I put 1psi of pressure into a container then the absolute pressure must be 1.07ish bar (1 bar being 14.5psi) as it was already at 1 bar. My foot-pump starts at 0 psi not 14.5 psi on the dial so a radiator cap with a tolerance of 1 bar (as specified by manufacturer) must in effect be a 2 bar cap. The 1 bar specification is the max pressure over atmospheric. So I would expect the water inside a max pressure 1 bar rated rad the water would boil at about 120.

If I therefore pump 30psi of pressure into a radiator it must have an absolute pressure of just over 3 bar. So, if the max pressure rating of a radiator is 1 bar this must mean an increase of 1 bar over atmospheric, 2 bar absolute.

If the original OP pumped 30psi into a standard rad this would be just over double the max pressure it was designed to take and I was wondering if this led to the damage/splits. I know alloy rads can take up to 32psi but a standard copper/brass would be lower (hence the caps set to release at 15psi/1 bar).

[Jhonno]

Probably my bad actually. Only half read it I think, due to being on my phone @work.

Yeah I think you are right. 1 bar cap = 1 bar above atmosphere. Still think it is 2 bar-ish though.

[rossybee]

You're both getting in a pickle

A 1bar cap is 1bar above atmospheric which is aka barg..Taking atmospheric into account is known as bara.

The majority of day to day pressure equipment (gauges tyres etc) is barg, so putting 30 psi in a rad is effectively doubling its operating pressure, not ideal...

Hope this clarifies things

[TimJM]

rossybee said:

You're both getting in a pickle

A 1bar cap is 1bar above atmospheric which is aka barg..Taking atmospheric into account is known as bara.

The majority of day to day pressure equipment (gauges tyres etc) is barg, so putting 30 psi in a rad is effectively doubling its operating pressure, not ideal...

Hope this clarifies things

Yes, I started to doubt myself earlier and got very confused.

So as suspected putting 30psi in a copper/brass rad is a bad idea and it would not be unexpected if the small pipes gave way as the OP said even on a brand new rad at this level of pressure. I only wanted to clear this up as I may be re-using an old Cerb rad in another project and wanted to know the max pressure to test at and thought 30psi was high.

So, as a general rule when pressure testing a standard rad with a foot pump 14-15 psi should be the max you use, any more would risk damage to the rad. Got it.

[Paul.B]

Is 1 Bar not = 14.8 psi?

(Just trying to clarify)

[TimJM]

Paul.B said:

Is 1 Bar not = 14.8 psi?

(Just trying to clarify)

Well I always worked on 14.5 but 14.8 sounds close enough.

[rossybee]

14.5, so 2bar is 29psi.

I think we're talking roughly here, but not to a factor of 2

[rossybee]

http://www.cleavebooks.co.uk/scol/ccpress.htm

[jackwibble]

It's a Range Rover core with TVR side plates to give the specific pipe exits a decent back street rad man should be able to sort it for a lot less than an ally one, plus you wouldn't have any electrolysis issues to worry about.

[TimJM]

jackwibble said:

It's a Range Rover core with TVR side plates to give the specific pipe exits a decent back street rad man should be able to sort it for a lot less than an ally one, plus you wouldn't have any electrolysis issues to worry about.

Electrolysis issues to worry about? I have an alloy rad, should I be worrying about something I'm not?

[FUBAR]

o/t nemasis are you the person with the info on the 'build' of my Cerb?

[FUBAR]

nemasis said:

you have mail

Thanks for taking the time to chat Very enlightening

[jackwibble]

TimJM said:

jackwibble said:

It's a Range Rover core with TVR side plates to give the specific pipe exits a decent back street rad man should be able to sort it for a lot less than an ally one, plus you wouldn't have any electrolysis issues to worry about.

Electrolysis issues to worry about? I have an alloy rad, should I be worrying about something I'm not?

Well even cheaper then if its all RR cheers for intel NEMASIS

Lots of articles about electrolysis on the mighty Google last ally rad I saw eaten by it was on a 12 mth old JCB cost £10k big ouch as it was just out of warranty