When my mechanic friends and I talk about common problems with cars we usually wind up discussing specific vehicles that in many cases have around 100,000 miles or have reached 10 years of age.
This is often the breaking point when even the best built automobiles will start asking for expensive repairs. This page focuses on failure of the water pump on high mileage vehicles.
If you would like to investigate a different car problem you can search through my automotive content using the search box at the bottom. You can also type in a specific problem in the question box on the DIY auto repair page and speak with a professional mechanic.
The replacement of the water pump will often provide a few challenges for the do-it-yourself driveway mechanic that they did not anticipate.
Why is a leaking water pump something you are likely to run into on vehicles with high mileage? Manufacturers are making the same quality water pumps that they did years ago. In the old days automobiles seldom went over 125,000 miles. vehicles today are used well over 150,000 miles.
Even the worlds greatest parts will need to be replaced at around this mileage. This common car problem will affect almost every vehicle made today.
Whether it is a Chevy or Mercedes-Benz, a water pump won't last forever. Since pump failure is one of the universal issues on so many different models, I really can't get into the exact procedures for all automobiles here.
However, we will talk about air bound coolant systems and how to correct it. Remember, there are many online auto repair programs that can guide you step-by-step through the replacement of your water pump.
I prefer a reference manual that directly sources the factory supplied repair information such as the All-Data web based auto repair manual.
What I would like to talk about today is what happens after the successful replacement of the water pump. One of the major problems with this repair is the refilling of the cooling system and removing the air from the system so that it flows properly.
A common complaint that I receive from driveway
mechanics is, after they replaced the pump the car is
overheating. In many cases when performing a part replacement I've found the cooling system can become air bound and will not flow coolant properly.
Air removal from the coolant system is different for each engine and some are so difficult to burp it's ridiculous. The key point to remember here is when you refill the cooling system after the job is done, the thermostat will be in the closed position.
This is the main cause of an air bound cooling system after the replacement of the water pump. After the vehicle has completely warmed up and the thermostat has opened, allow the vehicle to cool down completely and then refill the system.
Also while the radiator cap is off and the vehicle is cool, give the upper and lower radiator hoses a few tight squeezes. You may want to through a catch pan under the vehicle because some coolant may drip on the ground. This is a good way to shake loose some stubborn trapped air.
You must make sure the vehicle is completely cool before you remove that radiator cap and take it off very slow! The problems with cars are that some vehicles are very stubborn about removing air from the cooling system. The above procedure may have to be performed more than once.
On the other hand, some automobiles have a self-bleeding cooling system where they are vented back to the overflow bottle. An air bound cooling system will not be an issue at all on those models. Some vehicles have a bleeder valve to let the air out like on General Motors 3.6L 3.1 & 2.8 L v6 engines.
This is why I always recommend consulting a professional auto repair manual for all of the specific details. I just wanted to make you aware of the most common problems with old cars that I have seen.
If you replaced a water pump and you continue to have an overheating condition bleeding the air out of the cooling system should be your first concern.
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