Radiator fluid dripping from neck of remote coolant header tank

1990 v12 5.3 l.

and yes I bought a new radiator cap 16 lbs . Actually bought 2 and will switch them to see if the new one is faulty… Anyhow, after driving the car, parking and turning it off, I hear the Aux fan coming on . When it shuts off after 4 to 5 min. a cup full of radiator fluid drips down from cap /filler neck. I thought any extra fluids goes to atmospheric tank behind Left wheel and then goes back when car is cold. What could the cause be ? Did I overfill the radiator system / Gina


You need to verify the hose to the atmospheric tank is not plugged.

There is a metal adaptor in the hose just inside the fender pocket behind the wheel…that metal gets completely blocked causing pressure to build up and escape from the cap seal.



That means that cap is leaking. Note that might not be the cap’s fault; it could be the neck’s fault. Sometimes the flange is deformed too much for the cap to effectively seal against. Sometimes the flange is actually cracked, and those cracks can be really difficult to see. Whatever, that leak has to be fixed if you want the air purge scheme and atmospheric catchment tank to function properly.

Hi Kirbert,

you are right , the flange is deformed. We bend it back , it held 16 lbs pressure with the pressure device, but when we ran the engine, the neck did not hold pressure. time for a new header tank or weld a new neck on mine. I guess there might be 2 different models according to vin number. Thanks for your help. gina

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