300SEL 3.5: coolant is disappearing

[Frank Reiner]

Martin:

Brazing, in the sense of brass or bronze welding, will involve temps and heat input to the parts that is too high. Radiators are assembled with soft solder, i.e., tin/lead solder, which is what is also used in copper plumbing.

Easier to do with the radiator removed; you'll be doing flat work that way, rather than vertical.

[werminghausen]

Originally Posted by Frank Reiner

Martin:

Brazing, in the sense of brass or bronze welding, will involve temps and heat input to the parts that is too high. Radiators are assembled with soft solder, i.e., tin/lead solder, which is what is also used in copper plumbing.

Easier to do with the radiator removed; you'll be doing flat work that way, rather than vertical.

Hi Frank,
I used the same solder flux and heat as I use in copper piping...but no lead involved in the new solder.
It is a tricky thing to do this radiator... took me 3 attempts until the leak was sealed. Having the radiator horizontal is a must.
The solder was not flowing greatly unfortunately as it does with new copper fittings.
I ended up building up some material of solder until the leak was gone.

If it leaks again over time I am going to a radiator shop and let them do it.

Martin

[werminghausen]

Maybe the modern soft solder used for copper piping is not quite compatible with the old school solder of the radiator (w/lead?). Probably this is the reason the two alloys didn't want to connect smoothly.
So far the radiator is tight....
I was using 30% MB blue/green coolant (which is BASF G-48) because this is the only coolant available from MB/Oman. I'd liked the yellow one (BASF G -05).