Coolant flowing from radiator cap at speed

namvetmike said:
If I drive over 40mph coolant comes out at the radiator cap. The radiator is new with a qual radiator cap. Any suggestions on how I can fix this!


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I had the same issue, I made mine own gasket with some large rubber washers (you have to cut and play with it until you get a good fit).
 
As Bill mentioned in post #16, I had same problem with the Quail cap and tried & made new gaskets but it always spit water droplets out, around the hinge when I went over 45 - 50. I bought the standard cap and it cured the leak.
 
To eliminate the overheating question, either install a temp gauge or shoot the radiator when warm with an infra-red thermometer, $30 at HF. Most likely lowering coolant will "fix" the problem. I call it QUAIL INCONTINENCE, caused by pumping more than the radiator will accept.
 
I thought this was usually caused by the absence of the baffle under the fill hole. An easy solution is to add a thermostat, and don't fill to the top, as noted.
 
I just repaired the same problem with my Model A Ford. Look how high your overflow tube is inside of the radiator neck. If it is down several inches from the neck of the radiator add a piece of gas line hose to raise it up into the radiator neck. This corrected my sprinkling on the windshield and it keeps an extra quart of antifreeze in your system. If you are satisfied with the results you can remove the gas line and swedge a copper tubing to fit the overflow tube and epoxy it on for a permanent repair.
 
Joe K said:
Other solutions involve trimming down your water pump vanes (to reduce the quantity) or putting a "flow restrictor" (sold by the parts vendors) in the upper tube, or incorporating a thermostat (sold by the parts vendors.) Any of these will not make a sensible change to your motor temperature as the wide open flow is probably too high anyway. (and the biggest resistance to heat travel is at the copper tube/air juncture at the radiator exterior.)


Joe K
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As I read the OP, I smiled to myself anticipating that someone would come up with something like this. It is an old wive's tale to say that the pump can cause overflow issues. There is a thread on the other forum at the moment where a guy (Greynomad) explains why. Trimming vanes, restricting water flow (so long as it's not too much) is voodoo. The ONLY water available to the pump to pump is what has already gone through the radiator. It is obvious that water cannot be created from nothing so whatever amount of water available to the pump is what it pumps and there is therefore the same amount of space in the radiator for the pump's output. Barring an increase in volume due to steam (boiling) or exhaust gasses (blown head gasket or cracked head), the cooling system cannot oveerflow once it has reached it's happy level.
 
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