Overheating blowout, bad pump

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Craig Smith

1966 Valiant 200, Super 225
Joined
May 26, 2014
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Minneapolis
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It was like Old Faithful, Antifreeze blowing out all over the car and engine compartment, with the cap on. Luckily I had a gallon of water and I got home. I have a newer water pump, flushed the radiator about two years ago, and the temp had been spot on - 190 degrees. I've had no problems until this.
So I did a Prestone flush and put on a new rad cap. Now the good stuff. When I took out the thermostat there was 8 inch or so wire rod stuck through it. It looked like part of a coat hanger! I cannot for the life of me guess were it came from, but it was obviously the problem or part of it. I put in the new thermostat.
I believe I need 13qts. to fill up the radiator, but after 8qts. it was full. I drove a few miles, came back, and carefully removed the cap. There was a little bubble over. The temp at the opening was about 185. So that was OK. I topped of the radiator - still about 2 gallons total coolant. Now I'm wondering if the pump is blocked. I don't see any movement of the coolant. The bottom hose is cooler, the top of the radiator is hot. I'm thinking that there is no circulation so the top coolant boils. I'm planning on replacing the pump tomorrow. Do you think I'm deducing the right problem, and the right fix?
 
It was like Old Faithful, Antifreeze blowing out all over the car and engine compartment, with the cap on.
WHERE was the coolant spewing from? You have to locate the leak...

I believe I need 13qts. to fill up the radiator, but after 8qts. it was full.
The engine block retains some of the coolant. Full is full.

The bottom hose is cooler, the top of the radiator is hot.
Normal. The lower hose SHOULD be cooler- the top tank is hot coolant straight out of the engine; the bottom tank and hose is coolant that has gone through the radiator and cooled down. That is how the radiator does it's job.

It looked like part of a coat hanger!
I have NO idea why that was put in there...? Serves absolutely no purpose.
 
Probably left over from when the head was cast, I got some wire like that out of a couple of heads that I have worked on.
Dutra talks about this in his book on these engines.
 
Probably left over from when the head was cast, I got some wire like that out of a couple of heads that I have worked on.
Dutra talks about this in his book on these engines.
That is correct. The foundry process for making the cores that form the open shapes inside the cylinder head and block used wires to give the cores enough strength to be handled and set in the mold. That core process was typically called ‘oil sand’. By the early ‘70s the oil sand process was replaced by what was called the ‘hot box’ process. The hot box process produced cores that were stronger and dimensionally more stable and then wires were not used.
By the way of the perhaps billions of cylinder heads produced with the oil sand process, each having 2 to 4 or more wires in them. Yours is the first one that I ever heard about where a core wire moved and got into a thermostat.
 
And there's a thread where it's become painfully apparent that a whole run of defective/mis-assembled Slanty pumps are out there, on .org....
 
Just drove home from cabin - 120 miles. I stopped twice on the way down to check the radiator and fluid. First stop the pressurized coolant bubbled a little when cap removed. About 195 degrees. Added a half gallon of water. When I started the engine I could finally see some movement in the coolant (like the pump was now working). I hadn't seen that the previous day. Second stop no bubbling when cap removed and only measured about 185 degrees. Radiator was still full this time and the coolant seemed to be circulating. Checked it again when I got home - same readings. Once that wire came out it seemed like things slowly got back to normal. Consensus around here was that someone was jerry rigging some home-made fix. But the casting wire theory makes more sense.
 
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You wouldn't see much fluid movement in radiator unless/until thermostat opens, at 185, a 195* thermostat wouldn't be open yet
 
Your rad core might be blocked. They can & do block up with sediment with miles & time. This would cause boiling & water to be ejected via the overflow. So it needs water when you go to check it.
 
By the early ‘70s the oil sand process was replaced by what was called the ‘hot box’ process. The hot box process produced cores that were stronger and dimensionally more stable and then wires were not used.

My 1974 head had around 7 of those wires in it. So they were still in use until then at least. But it's hard to see how one could get jammed through the thermostat unless someone did it on purpose.
 
found one in the block behind a expansion plug too. I saw it in there ad pulled it out with a pair of ling needle nose pliers. Never seen a rigid wire make a 90 degree through a stat! SABOTAGE!
 
yeah and after all those years and possibly (at least) 1 trip thru the hot tank over the years and those wires are softer/easier to bend than a coat hanger....
 
I'm gonna go with a PO sabotage. It's out of the system and I'm driving again, no problems. Thanks to everyone for the input, over and out.
 
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