Here's what a failed water reservoir looks like.

[Pablito]

perfectlap the cylindical tube is part of the electonics of your cooling fan....apparently some sort of regulator, It should be in good condition for the proper cooling fan operation, verify your fans are operating...failure in one of them will cause your reservior tank to burst and your water pump to give in not to mention your cooling radiators to bleed green.....

[Perfectlap]

if the cooling fans were opertaing fully, wouldn't this trip the check engine light?

[deliriousga]

Originally Posted by Perfectlap

if the cooling fans were opertaing fully, wouldn't this trip the check engine light?

Do you mean "if the cooling fans were not operating fully"? I don't think the CEL monitors anything with the fans, just emmissions issues. I think the red light on the temp gauge will start blinking if one of the fans fails, but I don't believe it can tell if it is just running a little slow. I know it starts blinking if the engine compartment fan fails. It may show up as a higher temp reading if it's pretty hot outside and one fan is not blowing at full capacity.