How can you tell if you have a bad water pump?

[TerryWalter]

We have a '03 Camry XLE 4 cylinder 2.4 with 109,000 original and I', wondering if my water pump is going bad. I have replaced the thermostat and radiator cap but the lower radiator hose is always cold and the top one is very hot. I'm also not getting hot air on the passenger side of the car now but very hot air on the drivers side. Everything is pretty much original except the timing belt has been replaced about a 1-1/2 ago. How can I tell if I need to replace the water pump and would this cause the cold air on the passenger side of car because the water is not getting circulated.

Thanks,
Terry

[Brian R.]

The only definitive signs that you have a bad water pump are either a coolant leak from the timing belt area, or if the bearing fails and it locks up. A poor coolant flow problem is usually a thermostat or partially plugged radiator and shows up as overheating on your temp meter.

A cool lower radiator hose is not meaningful. It is receiving coolant from the radiator and if flow is restricted by the thermostat, it can be rather cool. Since flow is always restricted by the thermostat to some degree, this is not a symptom of a problem. In Wisconsin, at this time of year, you probably have very little coolant flow in the engine because it is very cold coolant coming from the radiator. This amplifies the difference in temperature between the upper and lower radiator hoses.

Conversely, the upper hose is always hot (at operating temperature) because it is receiving coolant from the engine. Also, not a symptom of a problem.

It is unlikely that the problems you describe are caused by the water pump. You didn't say that you have an overheating problem at any speed. Do your radiator fans stay on all the time without airconditioning or defrost on? They should cycle on and off in stop and go traffic. There should never be a change in the temperature meter once it reaches operating temperature.

The temperature difference between the two sides of the car from the heater is possibly due to a problem with the heater air flow control or a blocked heater core if you have more than one core. If you have thermostat settings for interior temperature, it is difficult to judge where the problem is. A wrong temperature output from the passenger side can be in the electronics, either in valve control or temperature detection or settings.

Try putting a piece of cardboard in front of the radiator so that it blocks around 1/2 the radiator core. See if this helps your heating. Take it off immediately if you notice higher than normal temperature on your gauge.

[TerryWalter]

Thanks for your reply, it is very informative.

The temp gauge gets to just below the 4th line and stays there constantly so it is not over heating but I need to add a little coolent almost each day. I do not smell any coolant at the tailpipe so I don't think that I'm burning any and I don't see any when I check the dip stick for oil. That is why I thought maybe a water pump was the problem. And the fans seem to operate normally because when I get home from driving and I pop the hood I do notice the fans working properly.

What I don't understand is if the heater core was blocked or plugged up why would I be getting heat on the drivers side but not on the passengers side of the car. I looked at the manuals that are available for my car here on the Forum and I cannot see what the problem maybe.

How would I go about flushing or back flushing my system out and seeing if that is all it needs. In the past I would install a fitting in the heater hose and back flush it out where the radiator cap would be. But this was back with my old cars like my 1968 Javelin or 1978 Lincoln Towncar. It was a lot simplier then.

Any more advice would be great.

Terry

[Brian R.]

The need to add coolant daily is a problem. You may have a bad water pump seal or a leaking freeze plug or possibly some other leak. Using a mirror when necessary, check all sides of your engine for signs of a leak. Check your hose connections for leaks - make sure they are all tight. You didn't say if you had electronic heat control in your interior. It is hard for me to figure out the problem related to uneven interior heating if you have electronic temperature control. Try the cardboard.