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1971 Ford Ranchero 302 (1970s block, stock internals.) Auto 3 speed.

So today i went and got a new rad cap, hoping this was the problem. I jacked the front end up and filled it up with coolant to the cold line. Started the car up and let it warm up with the cap off. No issues/bubbles/spraying out... untill the thermostat opened up. then all hell broke loose lol. Just started pouring out the rad. So i slapped on the new rad cap and within 1 min the cap opened up and it let the water out. About half of the radiator worth.... Also if i let it run with the cap off the water level in the radiator will fluctuate. It goes way down then goes straight back up and overflows a bit. Ill link a video.

Ive recently taken the water pump off to find theres nothing wrong with it. And a clockwise pump.
Replaced the thermostat to a 195, which im going to change to a 180.
Cleaned out the radiator of scale with vinegar and it flows nicely.

Today i took off the T stat and stuck a hose into the waterpump and flushed the system untill clear water was running out the intake manifold. But, when i put it back together and ran it for a bit with just water it turned green again?? There some blockage somewhere only letting a little water thru at pressure?

Does this sound like a water jacket blockage?? I want to make completely sure before i start tearing this thing apart.


Any help will be appreciated,. Thanks
 

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I understand that. But even with the cap on the radiator will still drain about halfway. I bought a brand knew 13 psi cap and it made no difference. Should i go higher psi?
 

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I dont know the exact temperature. The temp gauge does not work, but im going to get a new mechanical one soon. But it pukes once the thermostat opens, which is a 195. So i imagine around 195 degrees.
 

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It shouldn't boil at 195* unless you are way up in the hills somewhere......sounds like a blown head gasket......wrong water pump rotation......bad thermostat......clogged water jacket or radiator??:|

Wish I could be more help but not being right there it's just guesswork!!:frown2:
 

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I understand that. But even with the cap on the radiator will still drain about halfway. I bought a brand knew 13 psi cap and it made no difference. Should i go higher psi?
No don't go higher pressure. Do you have an overflow tank? The small hose on the side of the filler neck should go to a tank, and the end of the hose into the bottom of it. With that, you fill the radiator cold, let it belch into the overflow through the small hose, then when the engine cools the fluid gets sucked back into the radiator. The cap has to be the one designed for that specific radiator.

Also, you need to have a thermostat installed, because that helps control flow from the pump.
 

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-Thanks guys, Ill install an overflow tank, itll probably help. Heres some more info.
-Brand new thermostat, I recently took it out and tested it so no problems there. And it is in the correct way.
-Also taken the waterpump off recently and it also is the correct clockwise pump for a v belt.
-I let a gallon of vinegar soak in the radiator ( out of the car) for 5 or so days and got a bunch of scale out, and it flows nicely with a hose in it.
-No signs of a blown head gasket, water has no fuel smell or exhaust bubbles coming out. And no smoke out exhaust or water in oil.

Im going to remove the intake manifold and see if theres any evidence of scale blockage.
 

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Your video makes me think blown head gasket.

Also your idle seemed kinda high in the vid. Was it? or was that just the camera made it sound fast?

If it was fast, what happens if it idles "normal" say 750-800 rpm?

I had one once that did the same as yours.
"No signs of a blown head gasket, water has no fuel smell or exhaust bubbles coming out. And no smoke out exhaust or water in oil."

Yet the head gasket was blown. Just had that same fluctuating water level in the rad and would puke out the coolant on a short drive. No overheating until it ran out of coolant.
 

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Just to be sure, when you fill a system

1 - fill it to the top
2 - run it at idle with the cap off until the thermostat opens and it sucks a bunch in, it'll breathe and burp then just drop like a rock
3 - top it off and put the cap back on

If it doesn't drop, thermostat could be bad or backwards, if it continues to build pressure not just heat expansion, but like a compressor, it's a bad head gasket
 

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Yea. Im just going to replace the head gaskets/intake gaskets. Also the thermostat just to make sure. The car was sitting for nearly 20 years when i got it a month ago so they should be replaced anyway.

Another question, does anyone know how much a machine shop may charge to machine the heads flat? Or should i even bother?
 

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Another question, does anyone know how much a machine shop may charge to machine the heads flat? Or should i even bother?
If they are warped, toss 'em. Replace with a new set of Edelbrock aluminum, or another reputable brand.

Since you are committed to doing these parts, gaskets, I'd suggest that you consider a complete gasket/ seal set (not too much more $), pull the engine out and do all the gaskets. That will allow you to inspect the bottom end for bearing play and overall integrity. Don't disassemble the rotating parts. Then you can clean the block and paint it, for a nice clean, leak-free engine.

Then you can degrease/ clean/ paint the engine bay.

A little more work, probably rental of an engine hoist and stand, not too much money and a much better end result.
 

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Around here they charge 75 a cut, but Omaha can be expensive for machine work, high property and income taxes :(

So 150 for two head gasket surfaces, 300 if you do the intakes too, 450 if you do the exhausts too. Even though I throw my guy a lot of money, and he makes it up in other areas, he doesn't come too far off that price...
 
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