High Pressure in Radiator Tank, Car Heating UP ?

Question

First symptom was the car heating up. I opened the bonnet and could hear and see steam in a jet fashion (like a kettle boiling) coming out from the top plastic (becolite) radiator tank.

Initially I thought it was just due to wear n tear and the radiator needs to be repaired (or changed) but after getting that small leak repaired in the plastic I realized that the high pressure leakage was in fact a symptom of some underlying disease.

I started pouring water after getting the radiator repaired. Started the car and pumped the accelerator. Instead of the water/coolant level going DOWN it paradoxically went UP with HIGH pressure which I then realized was the reason it cracked the plastic radiator tank in the first place.

Somebody told me that the thermostat valve has choked the circulation and is blocking it causing the high pressure. He removed the valve, poured water, tightened the coolant/water cup on top and pumped on the accelerator waiting for the fan to start. Then suddenly the top plastic radiator tank BURST open separating from the main radiator !

I was infuriated and drove back home with the coolant/water cap loose (to avoid high pressure).

So it again boils down to the same question WHY the HIGH PRESSURE (especially on pressing the accelerator) ?

Before I get the radiator replaced I want to be sure that the cause of the pressure is removed.

Thanks. Appreciate a detail reply outlining all possibilities.

(btw car is 1996 Honda Civic)

Answer 1

you blew a head gasket friend

Answer 2

Sounds like a blown head gasket to me.

Answer 3

I would try a radiator flush before buying a new one.  I would think that a clogged radiator would act in the same way.  Has the car sat for awhile, perhaps causing some rust to develop inside the radiator?  What color is the fluid?  If it's a brownish color, I'd try a flush.  

Answer 4

It sounds like your head gasket is gone & that is why your car is overheating. You can test this easily enough by taking it to a mechanic & have a "TK test" done. This checks the coolant system for carbon monoxide (engine fumes). Something you can check for yourself, although it's not fool proof, is remove the oil filler cap & check the inside of the cap. If it has a mayo like substance on it then book it in for the gasket.

Sorry to be the bearer of bad news.