What are some of the signs if my water pump would be going out?

Hi,
My 626 is also having coolant leaks off and on and idles att high rpm on those days, but runs smoother when i fill it up with coolant. the mech said i need to have the water pump replaced, but i was wondering what are the symptoms of a bad water pump..will keep you posted if i get to know more..
Adwait

Water pumps are typically driven by belts through a pulley that bolts onto the pump shaft flange. A water pump consists of a casting, an shaft with an impeller, and a seal which keeps the coolant from leaking from the pump. Some water pumps need to be bolted on using a gasket to the engine block, so if the gasket does not seal properly, a leak can develop there. Mazda water pumps usually have a back cover with a gasket already installed and there is an inlet tube with an O-ring and an outlet tube or hose.

Many waterpumps have a weephole in the casting close to the shaft. If you see coolant seeping through the weephole, you have a bad pump.

so in summary, the most common failure mode of a water pump is a leaking shaft seal. There could be other source of leaks, such as bad gasket on the back cover(or gasket between the engine block and pump housing), and a leaky O-ring of the inlet tube (as in case of Mazda Protege).

This is a coincidence, but I happen to have a water pump for a 92 Protege LX (1.8 l DOHC engine) which I changed on my car preventively and it was a perfect water pump when I took it off. Free to anybody if you want to pay a few dollars postage. this is a genuine Mazda pump and it cost about $ 70 . waterpum

Will this water pump fit a 626 (2.5DOHC V6)
Is it easy to replace the water pump, in other words can i replace it myself. I think one needs to replace the timing belt also? How critical a job is that?
Thanks
Dwight

Anonymous. I guess the first thing, your saying, is to have it professionally looked at to determine if it's the pump or seals. My check engine light recently came on but went off and I noticed a liquid under the car towards the very front. The antifreeze level has been fine because that was a concern. No odor or color though to this puddle. If it does happen to be the pump I would be interested if it would be the right one. I'd have to get the specs off my car.

As I said in my post above, a leaky shaft seal is the most common problem with a water pump. The seal is part of the water pump. It keeps the coolant from leaking past the rotating impeller shaft. When a water pump is rebuilt, they typically only replace the shaft seal and the bearing, and a rear cover gasket, if there is a rear cover. Impellers are usually made of metal, so they do not alway need replacing.

I looked at the fuel pump I have and it too has a weep hole in the shaft. This weephole must be dry - if it leaks or seeps coolant, the seal is bad and pump must be replaced.

The Mazda part number for the 92 Protege LX water pump is 8AB8-15-010. I stand corrected, this water pump does not have a rear cover like some other water pumps, and it bolts to the engine block. There is a gasket betwen the two. There is also a gasket between the coolant inlet pipe and the pump body. The inlet pipe does not come with the pump but is has a branch pipe called water bypass pipe, and this pipe has an O-ring which should be replaced when changing the water pump.
So to install a new pump you need two gaskets, and the bypass water pipe O-ring.

To change the water pump, you essentially have to remove and reinstall the timing belt. This is why I changed my water pump preventively when replacing the timing belt. If the pump must be replaced by itself, it will be a $ 300 job just for labor.

You can do the job yourself if you are mechanically inclined. However, there are some precautions that must be taken when re-installing the timing belt. When you remove the belt, the cam sprockets will move out of alignment slightly because the valve springs exert tension on some cam lobes. You must realign both sprockets when you slip on the new belt, otherwise you will install it icorrectly. Mazda also makes a special tool for removing and properly torquing the crankshaft pulley bolt. The tool part number is 49 D011 102, and it is called "crankshaft lock tool". Only Mazda dealers sell it. If costs about $ 50. You can get by without this tool if you have an air impact wrench, but you must be careful not to overtorque the bolt. The crnakshaft lock tool allows proper torquing of the nut wtih a torque wrench.