I've noticed, and read, that the GMC radiators have a relief valve, and the cap is fixed. On Chevys, the cap is vented and no relief valve. My truck is a GMC and has the relief valve. When I took the radiator to service, the guys almost cut the relief valve (dindn't knew what it was, never senn one), but I stopped them. Shall I trust the valve is working properly (it is not stuck) and buy a closed cap or by the vented cap, just in case. If my truck doesn't have the thermostat, do I need to buy it?
