Radiator cap drain tube - check it

[readyman]

After cruising for a while at highway speed. A mile or two before running out of fuel I noticed a mist, then a spray, then streaming fluid coming from under the hood. It was streaming from the hood side panels across the fenders, on the windshield. Well then the engine stopped and the fluid leak took second to rolling as far as possible towards an exit.

After getting back to the shop I tried to trace down the coolant leak. Well to make a long story short, the radiator cap drain tube was completely plugged, every inch bottom to top! The coolant overpressure was blowing coolant thru the cap, hose connections, gaskets, it was all over. I could not ream the drain tube out because of the sharp turns in the tubing so I cut it near the cap and replaced it with some nylon flex tubing, and it won't corrode.

So a word to the wise, check your radiator drain tube, it could be a mess later otherwise.

 

[maddawg308]

I had this problem with my radiator drain tube in the 1970 w/w truck I took to Gilbert PA this year. Took me a while to figure out what it was. It was a combination of a clogged drain tube, and I overfilled the radiator fluid.

Question, what are those drain tube made out of? I find it hard to believe a copper line would be jammed with as much corrosion as they are, it's almost like the drain tube was made out of steel.

Great field mod, readyman! That nylon replacement hose will be much easier to fix, or replace, next time!

 

[readyman]

Yeah, I said the same thing. Steel? Is this a joke?

 

[acetomatoco]

put your maggot on it ...looks like dirty coppah to me.

 

[acetomatoco]

The iron comes from junk and rust in the engine block... do not blame the drain tube for poor maintenance.

 

[Kwai]

Probably mineral deposits from the coolant and not corrosion. Use distilled water instead of tap water and you won't have this problem.

 

[FreightTrain]

Down this way we have a pest called a dirt dobber.Pretty sure part of your problem was one of these black pest or one of it's cousins.

 

[readyman]

Yeah,
Magnet checks it out as steel tubing. Do these radiator caps have gaskets? Still seems to be leaking arount the top of the cap.

 

[Blood_of_Tyrants]

Newer radiator caps do have gaskets. They are designed to hold about 15 pounds of pressure in the radiator so that the fluid inside has a higher boiling point. They also allow coolant to exit as it heats and expands. The cap is further designed so that as the coolant cools, it puts a negative pressure on the cap, which in turn draws coolant back up the overflow tube and into the radiator. That way you have enough coolant for all your needs and you don't waste it either. You DO have an overflow tank, don't you?

 

[readyman]

The 'brass cap' to 'brass radiator' seal is still leaking, a gasket of some sort would make more sense in between there. Nope no overflow tank, but theres plenty of room to add one.

 

[jwaller]

my cap has a gasket where the inner cap portion meets the rad. not around the large diameter where you grip the cap to turn it.

I seem to always overfill my rad when do ing service and it spits out the overflow in summer till it's at a happy level

 

[readyman]

jwaller,
Yeah, that thin brass disk is supposed to seal against the filler tube top? Hmmm.... Everythings bent on mine, that thin disk is wavy, and I block sanded the filler tube because it was wavy too. I'm gonna look for a thin gasket to keep coolant from streaming out and on to the sides of the hood. Excess coolant should go down the drain tube like it was designed.

 

[readyman]

Final solution for the radiator drain tube. Painted the inside of the short steel tube to keep it from rusting shut again. The plastic downtube can be routed better too.