Cleaning a radiator

[JregGT]

Evening folks, not a massively exciting post but i'm after any old wifes tales, or general useful tips on cleaning the gunk out of a radiator.
Basically I've got a G40 rad that I got when I bought the conversion, It has smooth end tanks, and looks to be double cored, I can't find a part number, but what looks liek the remnence of a Sticker. So i'm pretty sure its a G40 one. The fins are a bit bent etc, but it 'worked fine' in the donor car.
But it is absolutely filthy with grime, I imagine at somepoint the car was ran on very little if no antifreeze. My radiator is only a pattern part, and if accelarating hard from anything under 50 upwards hard, and running at 70 steady on the motorway the single spped fan appears to come on. The radiator on has been on for some years, so I want to put this one on, just to see if it makes any difference. But I want to get it as clean as possible first.
So in a very very long winded way i'm asking is there any addative I could fill it with for a night or so to loosen the grime then rinse out. I have flushed it with a hose a good few times and it keeps coming out lovely and brown! So i'm after a shortcut really!!

Cheers in advance everyone

Rich

[breadman]

Rich, whip the rad out then flush it using a garden hose. Just keep flushing until it runs clean then reverse flush, then flush the other way again. Give the radiator a good shake with the stubs blocked with your hands whilst it's half full or so. More reverse flushing repeated as many times as necessary until it runs clean in both directions.
Might take a while to clear but should clean all but the most blocked rad core.
HTH,
Richard.

[JregGT]

Thats magic Richard ta, top explaination, hoping its a decent rad and will clear this niggling problem! Picked up some fresh G12 today, so thats a job for the weekend!

Ta Matey Rich

[MartinB]

A good blow on the upper hose can also blow out some built-up crud too!

[Andy]

De-scaler for irons can work well on this sort of thing too.