the original honda radiator developed a hairline crack along the side of the plastic that tops it.

the four replacement radiators did not crack; the metal teeth holding the plastic top of the radiator begins to separate from the body of the radiator due to the tremendous pressure. in the initial stages, when the car is turned off and begins to cool down, the coolant seeps out around these teeth. then the separation gets bigger and the radiator fails.

the third radiator blew out at the bottom, while the latest radiator is leaking out from the cap. it's only a matter of time before it too will fail.

the dealer has no idea what it is. they even checked with the dealership where the car had been purchased (something i had alreay done). the car had all of its routine maintenance and nothing else required.

all the acura tech could tell me is that there is some sort of blockage. they want to start first with removing the water pump and inspecting. or it could be a cylinder sleeve, he says. the cylinder head has been pressure tested as has the engine. my mechanic, with 25+ years of experience, says this is the first time he has had no idea what is wrong with a vehicle that he has let out of his shop and advises me to skip the "witch hunt" and sell the car.

but to me the most plausible explanation i got was from my neighbor who said the engine had run hot and there is a small crack smaller than a fingernail at the very bottom of the engine block. the previous owner used an engine additive that plugged the hole. but since i've been changing the oil and not adding anything to the engine, the problem has returned. the heat and pressure has nowhere else to go but up and is relieved at the weakest point - the radiator. sounds plausible, and he's a shadetree guy.

all i know is that there is too much pressure being generated and no one knows why.

any more speculation? thanx for the feedback.