Wednesday, September 14, 2011

How can I tell if I need a thermostat or a new water pump for my 94 Honda Accord?

The engine is overheating after about thirty minutes of driving.

The oil and anti-freeze levels are fine.

The top radiator hose gets hot, as does the radiator itself.

The heater works fine, blows hot air.

From advice I received, I am gambling on changing the thermostat, but would like to be sure I'm not wasting time and money.

Also, does anyone know of any links which have videos or diagrams of how to change a 94 Honda Accord thermostat?

Thanks!How can I tell if I need a thermostat or a new water pump for my 94 Honda Accord?
Well a thermostat could cause the car to overheat if it was stuck in the closed position. or not opening fully. You could check the thermostat easily by putting it in a pan of water and heating the pan up and see if it opens all the way or opens at all. I did this on some of my cars before. I just looped a piece of wire through the thermostat so I could pull it out of the pan to check it. If you do go through the trouble to check it, I would replace it. Thermostats are cheap and changing it would save doing it perhaps later. If it was your water pump, I would think your car would overheat a lot sooner than 30 minutes. Also, when was the last time you had your cooling system flushed? If a lot of gunk is built up in your radiator, it could cause your car to run hotter.How can I tell if I need a thermostat or a new water pump for my 94 Honda Accord?
I'd suggest that if the top hose %26amp; radiator are hot, then the thermostat is opening properly. The heater blows hot, so it doesn't sound like an air lock. Check that the electric cooling fan works properly, then I'd go for the water pump.How can I tell if I need a thermostat or a new water pump for my 94 Honda Accord?
As long as the top radiator hose is getting hot both the thermostat and water pump are working. The pump has to pump hot coolant through the thermostat to heat the upper radiator hose. (Technically, it is not exactly that because the thermostat is in the lower radiator hose and sampling engine coolant, but the flow is the same.)



From your description of the heat building up over half an hour of driving I suspect the radiator is not working well. That often is the result of blockage, and that most often comes from using tap water (even just once if you are in a hard water area) in the cooling system or using any stop-leak in the cooling system. Radiator insufficiency shows up as the lower radiator hose being about as hot as the upper radiator hose when the engine is overheating (a thermometer, like a meat thermometer, is helpful). Another prime indication of the radiator being bad is the heat building up and never coming down. If the radiator is working the temperature should be returning to normal within a couple minutes of driving, even if the fan is not running. A plugged radiator has to be replaced - I've never known a flush to improve the blockage and rodding is almost as expensive as a new one... leaving you with a weakened and old radiator.How can I tell if I need a thermostat or a new water pump for my 94 Honda Accord?
I'd take it to a shop and have them check to make sure you are not getting combustion gases in the coolant. Since you say it overheats, I'd guess that you have a head gasket issue.

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