coolant overflow- sealed or vented?

NFGTragedy

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Oct 19, 2004
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Rochester, NY
I have an aluminum radiator and I got a polished coolant overflow and it came with a bolt to go in the top to cap it off... my question is... is the coolant overflow supposed to be a sealed environment or is it supposed to be vented?
 
HISSIN50 said:

Any idea on how to vent mine? It's just a bolt on the top that screws in?.. leaving it out would cause unwanted things to fall inside right? So what can I do to fix something up? Right now my overflow hose pops off once pressure builds up a little bit since I have the bolt on tight...
 
It's vented, but it needs to be the recirculating type.

That means if the line comes in from the top, it just can't dump coolant into the tank. That's a true overflow "puke" tank.

It needs to have it's line submerged or enter from the bottom and always covered in coolant. That way, when you shut the car off and the coolant cools, it contracts and draws coolant from the tank back into the radiator.

For a vent, all you need is a tiny pinhole up top.
 
Mike is right. I HATE syphon overflows. Much better is to have it be a bottom feeder (the line from the radiator goes to the bottom of the overflow. Just easier dynamics to deal with that way).

Assuming you have this and now have a spare hole at the top of the overflow which is plugged: You can probably install a 90* brass fitting (those bungs are often NPT tapped) and put a hose on the fitting and run it somewhere out of sight and harm's way. Coolant would overflow out the hose rather than out of the side of the bottle. Be careful of coolant hitting tire tread, etc.

Good luck.
 
NFGTragedy said:
Last time I checked banjo bolts have a hole from the bottom to middle of the threads in a bolt... not usually to the top and out. If you know of any that do go out the top I'd love to hear about them.


Well, i don't know your exact setup, but a banjpo bolt is only threaded halfway, so it won't go all the way in. The part with the hole in the side will be exposed. Maybe you could put a cloth sleeve over this or something fine to protect it further, but i doubt much of anything would enter that hole.

Just an idea really.

You could even drill out the banjo bolt through the middle from the reverse side.