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| | | | Joined: Oct 2006 Posts: 99 Wrench Fetcher | | Wrench Fetcher Joined: Oct 2006 Posts: 99 | 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
Well, my time went so quickly,
I went lickety-splitly
Out to my ol' 55.
As I pulled away slowly,
Feelin' so holy,
God knows, I was feelin' alive..... Tom Waits, Ol' 55
| | | | | Joined: May 2001 Posts: 7,438 Extreme Gabster | | Extreme Gabster Joined: May 2001 Posts: 7,438 | Yes that is the relief valve. It should be a 4 psi valve. The original radiator cap did not have a pressure relief valve.
The "stopcock" is your fill indicator. You should stop filling when coolant comes out there. You probably have your coolant level high. Set it at this level and try again. That may cure the puking. | | | | | Joined: Oct 2006 Posts: 99 Wrench Fetcher | | Wrench Fetcher Joined: Oct 2006 Posts: 99 | Thank you- that makes sense. The coolant is high- right up in the filler neck. I will try lowering it to the fill indicator.
Well, my time went so quickly,
I went lickety-splitly
Out to my ol' 55.
As I pulled away slowly,
Feelin' so holy,
God knows, I was feelin' alive..... Tom Waits, Ol' 55
| | | | | Joined: Oct 2006 Posts: 99 Wrench Fetcher | | Wrench Fetcher Joined: Oct 2006 Posts: 99 | Cletis- you nailed it- about 12 oz of antifreeze came out of the fill indicator, and then a hot Boston drive resulted in zero puking. Thanks.
Last edited by Dave Douglas 56; 07/13/2011 7:44 AM. Reason: typo
Well, my time went so quickly,
I went lickety-splitly
Out to my ol' 55.
As I pulled away slowly,
Feelin' so holy,
God knows, I was feelin' alive..... Tom Waits, Ol' 55
| | | | | Joined: May 2001 Posts: 7,438 Extreme Gabster | | Extreme Gabster Joined: May 2001 Posts: 7,438 | You're welcome. I appreciate you posting the results. | | |
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