1992 500SL. I had noticed that I was losing a small amount of coolant so following the advice of the group here, I went into the dealer to have him look into the problem. The service writer told me that it could be a $9 dollar hose replacement or a $900 radiator. He then called over a mechanic who pressurized the cooling system and pointed out bubbles coming from a miniscule, previously invisible, 1/8 inch long hairline crack running on the top of the radiator between the hose clamp on the drivers side back of the radiator and the small nozzle on the top of the radiator. Before putting the system under pressure, the hairline crack was not visable. Under pressure, very small bubbles were coming out of this hairline crack. The mechanic said $900 radiator replacement and that it needs to be done ASAP and that the car should really not be driven until this is done. Does this sound correct? Thanks JR