Mazda 626 coolant leak


Popped 1ltr of coolant into my radiator along with a lot of water and topped it up about two months ago. Was all great until I noticed my temp gauge rising slightly, went to check the coolant and it was almost empty. I shouldn’t be burning through coolant this quickly should I? Checked the oil and it looks ok (no milky liquid). There is a lot of rust around pipes but not sure if its around the coolant pipes or something else. Haven’t noticed any leaks on concrete either. Any advice or anyone know what’s wrong/how I can fix/check? Also, the radiator is producing a lot of this brown/rusty liquid? Is that anything major?


Seems like your radiator is rusted internally. My guess, you need a new radiator, likely some new hoses. Quite possibly a new radiator cap. Water pump may be leaking.
Cooling system needs to be flushed, then refilled with the coolant specified by Mazda.
Different types of coolants may not be compatible.
Modern cooling systems should lose very little coolant. Your vehicle is losing coolant when system is pressurized while driving. Coolant should not be discolored, retaining its original color.


Let me also suggest that the brown milky coolant and loss is caused by a bad head gasket.


Aluminum radiators don’t rust.

So forget that.

Have someone perform a cooling system pressure test to check for leaks.


The Mazda 626 was last made in 2002 so this thing might need some serious work . Yasmine does not seem to know just what pipes have rust so paying a shop for a diagnostic to see what it needs might be the first step . Then she can decide what to do.

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Coolant passes through steel and iron in cooling systems, as well as the aluminum radiator, so rust is possible. That variety of metals is one reason for using the correct fluid. Murky discolored coolant can result from too-long change intervals, wrong coolant, head gasket leaking into the cooling system, etc.


For future reference, you need to use a specific ratio of coolant and distilled water, not what appears to have been a random mix.


Get it checked out by a trusted mechanic (ask around, google ratings, yelp, etc.). If you’re lucky it’s some cooling system components that need replacement. If you’re not lucky it’s a bad head gasket. Check it soon before the engine seriously overheats, which could damage it badly.

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