I have a 56 gmc 3/4 ton with the 270 six, and we passed inspection today! It was a hot day in boston, 86 or so, and when I stopped, antifreeze was dripping from under the radiator. Engine temp was running 180 plus a little, and 200 when engine off and about to restart. Bummer I thought, new or recored radiator in my future. But I could not see the leak, and it stopped as it cooled (suspicious). I went out just now to look again, and I spied something I have not thought about in the 30 yrs I've owned this truck, a 1 1/2 inch wide by 3/4 inch deep metal cylinder soldered to the top tank of the radiator, with a button like end facing rearward. There is a tube soldered to the side of it that descends into the radiator mount about where the drips seem to come from. Is this a sort of pressure relief valve? If so I might be a candidate for an overflow reservoir- I have an old mercedes res, I could plumb it into the heater line with a T fitting...and there is a stopcock with a tube outlet on the other side of the top tank- I could plumb an overflow tank there too I suppose. Thoughts? The merz res has a 16 psi radiator cap. I know that's a bit not original, but i do not like dripping antifreeze- I have a dog, and they like it (smells sweet) and it is potentially lethal.
Last edited by Dave Douglas 56; 07/12/2011 5:15 AM. Reason: added to it
