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I seriously need some help here... As most of you know I recently finished a complete rebuilt on my 70 mach 1, now it is overheating to the point it boils. I have a 76 model 302 I used in the car freshly rebuilt all stock parts (except the intake is off a 68 289). I have replaced the water pump (twice) the thermostat, and just because I wasn't 100% sure, I pulled the heads to make sure the gaskets were installed correctly. I had the radiator rodded and cleaned and made sure the shroud was in place.Timing is set a 4 deg btdc (specs say 6 deg btdc)and still it boils over after 10 miles or so. Replaced the radiator cap that didn't help either. any thoughts??
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First thought: Are you sure you are running the correct rotation water pump?
What type of fan and shroud do you run? How about your bottom radiator hose? Is it kink free and are you sure that it is not collapsing?
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the water pump is a standard clockwise rotation pump, the fan is a solid 5 blade and the shroud and radiator are orginal to the car. The lower hose is kinda s-shaped but it is not collapsed. I took off the radiator cap and the coolant is circulating but with more rpm's the coolant is pushed out the filler neck not pulled down into the motor as would be expected.
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Did you compare the coolant ports on the intake to the one that came off the engine. If the blocked off ports are wrong it will cause incorrect flow through engine block.
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no, the intake that came off this engine got junked when I bought a edelbrock that I was using at first, I changed back to the 2bbl to try and save fuel as the cost is over $4 a gal here. I tried to find a 76 model 2bbl 302 intake but no such luck so I bought this 68 289 instead.
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[quote='Robertb40' pid='20616' dateline='1335667753
I took off the radiator cap and the coolant is circulating but with more rpm's the coolant is pushed out the filler neck not pulled down into the motor as would be expected.
[/quote]
From this statement right here I believe you have a reverse rotation water pump. I used an 86 302 in my sons 89 Mustang and didn't realize it was reverse rotation. It acted the same way. Circulating fine, but blew coolant back out the neck when reved up. Then about 10 miles up the road it was running about 235 degrees. With an 18 pound cap. They may have given you the wrong one at the parts store. Did you get it from a reputible parts store? It seems crazy, you could have gotten 2 wrong pumps in a row??? We got a pump for a 69 351 Windsor and it cured the problem. I really can't think of anything else it could be. The blowing back out the neck, points to reverse flow or restriction. Wish I could think of more. There just isn't anymore parts in the system. JTS 71 Mach1
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I bought it at Autozone... I do have the original water pump for this motor (the one that came factory on it) it worked fine when the motor was still in the granada,I rebuilt the motor and decided that I would put on a new pump so everything would be "new". I took the back cover off the original pump and the impeller is still solid and the bearing is quiet. I also found out the '68 289 intake I am using is different than the original,the '68 does not have a coolant passage across the back as the '76 did, I decided to put my Edelbrock performer 289 back on as it has the coolant passage across the back. I am using an adapter to be able to use my 2bbl carb and I am putting in a 160 deg stat to see if that helps at all.
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There is a guage tester that indicates the prescence of oil or exhaust gases in the radiater fluid that a mechanic at tires plus used on my diagnoses of this same problem on my 1970 Mach 1 with the 351 Cleveland engine overheating.
After all that changing of parts I finally found that my heads needed to be shaved at a machine shop due to the fact that they were warped slightly. This condition caused the gaskets not to seal correctly.
On your car: My first thoughts are that Id get an original 1976 "302" water pump from Ford or put your old one back on with new gaskets. I believe they are correct in the rotation problem because something doesnt add up unless the block is cracked inside between the cylinders somewhere and the cooling system is presurizing. This is entirely possible especially since the 302 has thin casting methods in thier cylinderwalls.
If you find exhaust gasses present and you know the gasket job you dod was good, then your block could be cracked slightly with a hairline fracture internally. This would cause the condition you specify as well as others mentioned.
If this is the case then you should hunt down a
351 Cleveland and make a monster out of that rad looking beast of a red hot hotrod.
The car looks amazing.....dont give up...
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I had the Heads checked about 2 weeks ago when I replaced the head gaskets they told me the heads were fine. I pulled the heads because I wasn't sure if I had a blown head gasket or a cracked head. If it were leaking exhaust into the cooling system you could smell it with the radiator cap off, not smelling anything... I also do not have oil in the cooling system nor is there water in the oil...
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I noticed you said you have the original pump from when it was in the Granada. Pull the back plate off of it, and the new pump, and compare the impellars. If the fins are not bent the same direction. Then you have a reverse rotation pump. If they are the same? Did the engine have any overheating issues in the Granada? Keep posting details. We'll all figure it out one way or another. JTS 71 Mach1
Ps are you running v belts, or a serpentine setup? If the serpentine is running on the back side of the belt to drive the water pump. That will spin it backwards. You may have a correct pump and just be turning it backwards? Just a thought. JTS