Overheating Big Block

[mprat]

Well still having the same old problem. The latest thing I have found out is the pressure in the radiator is really high, while watching the temp gauge
, I noticed that at 160 even before the thermostat opens up it is blowing water out the overflow and into the tank, cannot understand where so much pressure is coming from. I put a cap tester on and watched how high it would go and it topped out at 25lbs. But when the temp reached 160 the pressure on the cap was at 20lbs. There is no water in oil and none in exhaust pipes... what else could cause such a pressure increase.... and such an overheating problem... I did call the march company and they said that was not a reverse flow pump, its arranged so the water still flows the right direction as factory.... driving me nuts,, getting to the point of taking it to a mechanic or someone that is a lot smarter than me...

[shadowgray396]

Over heating and high radiator pressure is sounding like a head gasket problem.

[fleming23]

Originally Posted by shadowgray396

Over heating and high radiator pressure is sounding like a head gasket problem.

That was my thought too but if it is that and you would think it would be more noticeable

[mprat]

Don't they make a sensor you can detect the exhaust gas in the radiator. It acts like a head gasket but water is not getting into the oil or cylinders, pulled plugs and all look normal. I have heard to do a compression test and the one that is blown will read low... but still water in the cylinder would be quite obvious. When I was shining a light in the overflow and watching the water come in from the bottom it was blowing air bubbles for a couple of minutes still that is weird to me also....

[Hank70SS]

You would think with a blown head gasket one or more cylinders would fill with fluid during cool down, causing a hydro-lock when you try to start it up. Not every time, just depends on where the pistons are sitting in the cylinder when you shut it off.

[Hank70SS]

Don't think this is the real problem but 10 degrees base timing is not nearly enough for a big block. It will run cooler if you up the timing.

[shadowgray396]

I'm still leaning something is going on with a head gasket if you are getting bubbles in the coolant. But I'm not an expert on the subject only what has happened to me in the past.

Blown or deteriorated head gaskets account for one of the most common and obvious causes of coolant bubbling. If the head gasket material blows between a water jacket and the inner area next to the cylinder, compression gases will enter the water jacket and send air through the head and into the cooling system. Blown head gaskets produce profuse bubbling inside the radiator and expansion reservoir. Rapid overheating results

I have been there, Never knew I had a problem.

[mestorod70]

Try a re torque of all the head bolts..in order.!
See if any are loose...or perhaps pulled a thread in the block.
I had a pulled thread in my block that caused an overheat problem.
my cure was a heicoil...and changing from bolts to studs.

[mprat]

Well after a lot of asking, they do make a combustion leak test kit that lets you know if you head gasket is blown without having to guess. It uses a chemical liquid that changes color if you have exhaust gases in your radiator. It will be here at noon today had to order. At least it will answer one big question... I will update after I do the test...

[mprat]

Well I just finished the test. And it says it does not have a blown head gasket. Shows there are no combustion going into the radiator. That is one big relief and eliminates one big answer but still does not answer why the pressure and overheating. If you want to watch how this is done, go to "how to tell if your head gasket is blown" on the internet and there is a YouTube video you can watch. Now what could be causing the excessive pressure, and overheating????????