What would cause pressure build up in the cooling system?

Question

What would cause pressure build up in the cooling system?
I tried taking out the thermostat , Ive been leaving off the radiator cap just to drive around.

When I put the cap on it blows hoses

Last time I put the cap on it split the top of the radiator open ...boom!

Pull off head
copy that

Answer 1

It wouldn't hurt to do a pressure test to look for combustion gasses blowing in to the coolant through a head gasket,just in case.
If you notice pressure even when the engine is still cold that's the case.
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Now I know for sure the head gasket is blown

Answer 2

I have 2001 honda civic ex there's a problem with the coolant coming out of the overflow. Also my bottom radiator hose is cold and the top is hot with a lot of pressure. I changed the thermostat with the same result.
Also my cooling fan was not turning on so I uncooked the fan sensor on the thermostat housing and bridge it. Before I did all this the car wouldn't over heat at least that what temperature gauge is showing. It stayed a little under half way but the top radiator hose is getting hot with a lot of pressure and the bottom hose is cold. So I took thermostat out and the bottom hose is getting warm not but I still building up pressure just not as much. Also the heat would work after I drove it just not super hot and my temperature gauge would be by the cold mark. I'm beginning to think theirs a block some where in the system or bad water pump.

Answer 3

Very high pressure, above 14psi, in the cooling system could be caused by a leaking head gasket. As a matter of fact, I would bet on it! There are some products available to put in your radiator that have maybe a 20% chance of working. I would go to an auto store or Wal-mart and give it a try. If it doesn't work, you will have to replace the head gasket. The head gasket failure was probably caused by an overhaeting condition with the root cause being a failed water pump, or the belt or idler pulley that turns the water pump.

Answer 4

You are supposed to have pressure in your cooling system, if not THEN you have a leak. your rad. cap keeps the pressure in. Is it overheating? If that is the problem, then you need to replace the thermostat, and probably drain and flush the system. Straight water will not keep it cool, and will crack/bust the radiator if it gets too cold. If you change the thermostat, and its still overheating, time to check for another problem, but its not safe to drive around with the rad cap off, leaking fluid all over the place...remember that stuffs toxic. If you need more help, ask us!
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Yes if its blowing hoses, you need to do a pressure check to see if theres a leak in your head gasket. is the car smoking white smoke out of the tailpipe? I'm assuming that your blowing the upper hose (that runs into the therm.) is it clamped down. May sound stupid, but gotta ask. What kind of vehicle/engine is it, some have reverse flow heads.

Answer 5

Pressure build-up is NORMAL and required for proper operation of the cooling system! All cooling systems operate under pressure. The principal reason is that it raises the boiling point of the coolant and prevents the engine from overheating.

NEVER drive around without a radiator cap and NEVER operate an engine without a thermostat!

Answer 6

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you could just have a bad radiator cap on it,but those will do that also if a head gasket is blown on them,it releases more pressure in to the cooling system from the engine and that will cause a high build up of pressure,you might want to get that checked just to be sure that isn't it,if it is you will do damage to the engine if it isn't repaired ,good luck on it.

Answer 7

Pressure In Radiator

Answer 8

i have 7 chevrolet 6 cylinder cars. i am connstantly experiencing bursting coolant hoses/blowing up of radiator itself in all 7 cars. chevrolet agency is not able to give a satisfactory remedy . my 3 engines got overheated and damaged. thermostat replacement,radiator replacement, hoses replacement and radiator cao replacement were done. still no use.I have come to a conclusion that it is a radiator inefficiency to cool the 6 cylinder engine what causes the problem.

Answer 9

I have pressure build up in the radiator n white smoke is blowing out my tailpipe so what's wrong

Answer 10

You have a leaking head gasket. Nothing you can do to fix it except remove the head and replace the gasket. Another possibility is a crack in the head or block.