My aluminum block slant six 225 that I rebuilt from the ground up runs fine but after a few minutes it blows out all the antifreeze. I put a new thermostat in it and changed the radiator cap to a 13 lb cap, no change! Any ideas?

Some thoughts......

Sounds like you have some air pockets which are turning to steam and blowing out the water.

1. Is the heater core hooked up? Some times it takes awhile to purge out all the air.
2. Does your thermostat have a small 1/8" hole drilled in it to let some of the steam/air bubbles out? I would put the hole at the top so it will allow the air to escape......
3. Is the bottom radiator hose collapsing?

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Last time my Dart did this (overheated within 10 minutes) it was pilot error... I had installed the thermostat backwards.

Yup. Check all of the above, and drill a small hole in the stat, say 1/16 to 3/32 of an inch, mounted at twelve o'clock.

Once the thermostat is properly positioned, and air can be purged from the head as you refill the system, all will be well.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Run without the cap to purge the air.

Hopefully it's not the head gasket.................

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

It may be too obvious to suggest, but when was the last time you know for sure that the radiator functioned? When they get old, they can flow lots of water but transfer very little heat.

I finally replaced the 40+ yr old unit in my Valiant even though it *looked* fine, and the cooling capacity change was like night and day. Literally.

- Erik

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Lots of early Valiants and Barracudas have crossed my path.
Also a handful of other toys for variety now and then.

Kinda thinking blown head gasket also..any air in the system should have purged itself out by now.

You did use the correct head gasket, right? There is a difference in the gaskets for the aluminum and cast iron engines.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225