How would I know if the water pump wasn't working? I am trying to figure out a slight overheating problem and am probably just going to end upreplacing the whole damn cooling system...

 

The water pump, being rotated by a belt attached to the main pulley on the eccentric shaft, is constantly spinning - if it weren't you'd hear the most horrendous squealing sound. So, it's probably turning just fine - whether it's moving water is another issue...

Start out by grasping your engine fan and try to turn it from side to side (from left to right). If it moves freely and you can see the pulley on the waterpump being torqued each direction, then your waterpump bearing has gone out and will need to be replaced (the whole pump, not just the bearing).

If the bearing seems okay, look for coolant leaking along the front of the engine, below the pump. This can be caused by a 'weep-hole' that's designed to leak when the pump inner seal goes out. If that is leaking, pump replacement time.

If those are okay, check your radiator for leaks on the ground under your car - any slight leak in the coolant system will reduce pressure (normally 12-14psi) and cause the car to run a bit hotter than normal. Also, be sure that you're running the proper mix (50/50) of water to antifreeze for aluminum block engines. Running straight water will lead to higher temperatures, and potential corrosion in your engine.

If all seems normal, it may be caused by a sticking thermostat located just under the water outlet at the top of the waterpump. If the thermostat is sticking, it won't let enough coolant flow through to keep it at a normal level. Replacement of the thermostat is easy and fast, and should probably be your first course of action as far as replacing things goes.

A new Mazda factory thermostat has a 'jiggle-pin' which allows air to evacuate from the engine block before the engine heats up - install the thermostat with the jiggle pin at the top. HTH, and reply back - we'll figure it out.

 

some more data on cooling system. good luck.

http://www.wankel.net/~krwright/file...(3)cooling.pdf

 

Well the only thing i've seen my car leak is oil so Its not coolant.. i tried flushing the whole system a couple days ago and also replaced the thermostat.. And no coolant leaks that I could find and odd noises coming from the engine bay, except it does make a screeching noise every so often but I think thats just a loose belt. So what happens is it gets extremely hot up hills, it will get to the first mark on the hot side.. but only up hill, i can run the car at 120MPH all day on flat land and the temp wont move a bit... I did it the other day and it was about 50 degreese outside and it still got baking hot. So all i can think of is the rad isn't working anymore or the pump isn't pumping. The radiator, aside from 20 years of corrosion and crud, looks fine.

 

A radiator rebuild may not hurt. If they boil it down and rod out the core, you will get much more consistent flow and better cooling.

Also, be sure to check your engine fan to see if the clutch has gone out on it. This will cause overheating at anything other than high-speed driving conditions where air is being forced through the front end.

 

or simply get a new radiator. That's what I did. I was experiencing similar problems. After the rad was replaced = temp never reaches the middle of the gauge, no matter what I do, and normally sits at 1/3rd.

p.s. fan clutch failling = engine will overheat at low speed. radiator clogged = engine will overheat when going uphills, and eventually, when it gets real bad, under all circumstances