Mazda B2500 Overheats During Idle

[sethmac]

I have a 1999 Mazda B2500 that is overheating while idling or when the air is on. Just started hitting 104 days here in Texas so I'm sure that isn't helping the situation.

When driving the temp meter is at 50% but when sitting idle the temperature steadily climbs to the red line. I can bring it down by shutting off the air and giving it gas in neutral.

- When I first noticed the problem, the coolant well was dry (I know...just had a baby so I've been a little off my game)
- The fan is mechanical I believe and appears to be running fine.
- The upper radiator hose is firm
- The valve on the radiator cap has some brown residue/liquid dried as if released around it

I'm a novice but can like to do my own repairs. Any advice on where to start diagnosing what is wrong? Should I attempt to flush it or is that mute at this point?

[buckwill]

cupla things,, first,, i know this isnt the issue but lower rad hose is the one collapses but does so at speed, not at idle but good to check anyway, just buzz it up and watch hose, if it sucks close, replace it, but on to other more likely things, u sed brown residue at rad cap,, that indicates rust,, which sez that your coolant is low or no antifreeze, which suggests that most likely u have rust pooled in block or rad cores plugged,, first thing needed is a good block and rad flush followed by 50/50 coolant,,, check lower hose for rigidity and perhaps boil your thermostat for function, let us know, buck

[sethmac]

Thanks...finally got it home. I'm loosing coolant but can't tell where yet. Appears to be from the radiator but maybe a hose. Going to inspect further. It only appears to leak when running (not sure if thats relevant)

Thoughts? Approach?

[buckwill]

take the water pump fan belt off,, run it in your drive till its hot watch to see where the waters coming from,, or use pressure pump on rad twster to see where the waters coming from,