My 1965 Valiant (225 Slant 6) heats up fast and dumps plenty of hot water (under pressure) into the radiator, but the engine overheats- it is as if the coolant isn't getting through the engine. I understand that there is an engine block cleanout plug and I think it is the little one near the firewall, but I can't work it loose- I rounded off the bolt. What is going on with the engine? I tried removing the thermostat and adding system flush to improve circulation and clear out sludge, but no success.

The Block coolant plug on the left side of your engine(facing it w/ hood open), between the firewall and the oil filter.. if you get it out you will likey have to use something to clean it out... mine was very plugged up from sitting for 20 years...

You may have to pull your freeze/soft plugs and clean out the water jacket.

GL

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Mike C
http://cuda.iclownz.com
67 - Barracuda Coupe - 225 - Automatic

Thanks- What do the freeze plugs look like? Where are they?

They are round brass plugs. They serve 2 purposes, 1st is the holes where the plug go helps when the block is being cast, they release heat and gases if I remember correctly I'm not 100% sure about this but I do know they aid in the casting process. 2nd if the coolant in the water jacket in your engine ever freezes, the idea is the freeze plugs are meant to pop before it breaks the block, leave a pop can full in the freezer sometime you will see what I mean . If your engine is 67 or before you will have 3, and if it's after 67 it will have 5. They are in the engine block, below your Manifolds.

You will need to buy new ones, they CANT be reused, I would only buy brass replacements. The best way I have found for removing these is taking a screw driver on the edge of the plug and hitting it with a hammer, which will make it turn, then pull it free with pilars. To install the new ones, clean the mating surface well, then I put Form-A-Gasket the type the hardens, then get a large socket, the biggest you can find that fits in the freeze plugs so it spreads the weight out good. Then just hammer it into place.

_________________
Mike C
http://cuda.iclownz.com
67 - Barracuda Coupe - 225 - Automatic