How to Pressure Test a Cooling System

Pressure Testing a Cooling System is a great way to identify hard to find leaks by recreating the pressure your cooling system experiences out on the road whilst being stationary on your drive with the engine off.

[Hix]

I had a really slow weep that I just couldn't trace at all. To save resorting to pressure testing I bought some Ring RLD2 UV dye, it is brilliant stuff, traced it to a really slow weep on the EGR coolant pipe. The benefit of the UV dye is that the marker persists long after the moisture has evaporated away.

[andystagg]

Thanks for this, excellent as usual. I've just got my hands on a V70 T5 from 2003, it's great but someone has mixed red coolant in with the original green coolant, so it's now a nasty brown colour. Can i use my Sealy to flush this coolant out and and flush through distilled water before re filling with the correct coolant. I have seen your coolant flush vid but thought i could maybe use the Sealy to pressure flush, get out all the old stuff?