cooling issue

replaced water pump gasket as it was leaking. hooked everything back up, tried to bleed cooling system, temp gauge went up higher than normal, replaced thermostat. same result. there is a knock in the upper hose that is loud and can be felt, even after the car is turned off. is this just trapped air? is the thermo not opening?

My car has 143000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Sometimes air can be trapped in the cooling system, effecting circulation. Generally, a normal fill and bleed procedure will work. With the radiator cap off, run the vehicle with the heater on so coolant circulates throughout the cooling system. Slowly add coolant and allow the system to "burp" several times. Once complete, reinstall the radiator cap and allow the vehicle to run for a short time. If it continues to run hot, then shut it off and allow it to cool a bit.

The next step is to try the bleeder screw. The 3.7 ltr V6 has a small bleeder screw where the upper radiator hose meets the engine. Remove the radiator cap again to relieve any pressure in the cooling system. Locate the small bleeder screw. TIP: if this screw has never been touched to your knowledge, spray it with some penetrating oil and allow it to work for 5-10 minutes before attempting to loosen it. It is a small screw and can easily be broken with too much force. Once loosened,(not removed), top off the cooling system until you see some coolant come out of the bleeder screw. Once you do, tighten it back up and replace the radiator cap. Try running the engine again, keeping an eye on the temperature.

If this does not resolve the running hot issue, have a certified technician inspect the cooling system to see if the problem lies elsewhere. Continued driving while running hot can damage the engine.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

A thermostat that is stuck open can cause the engine to run colder than normal and turn on the check engine light. It may also cause poor fuel mileage and the heater to blow cool air. A thermostat that is stuck closed will cause the vehicle to overheat.
The most likely reason is a coolant leak. If there is a leak in your coolant system, there won`t be enough coolant fluid to effectively cool down your engine, resulting in overheating. Some other possible reasons why your Jeep might be overheating include: Broken radiator fan.
The most common reasons a Jeep Liberty is overheating are a coolant leak (water pump, radiator, hose etc.), the radiator fan, or a failed thermostat.
Why does my Liberty`s engine overheat? There are two main causes for engine overheat: The coolant does not flow through the system like it should. There is not enough air flowing through the radiator.
If the coolant tank is full, the problem may be electrical or mechanical in nature, in which case a tow to the nearest repair shop is definitely in order. A leaking hose, worn or broken fan belt, bad water pump, or malfunctioning thermostat may be the culprit.
The most common reasons a Jeep Wrangler has a coolant leak are loose hose connections, a broken radiator, or a failed water pump.
If you find that you`ve got a car running hot but not overheating there might be a few reasons: Clogged or damaged radiator. Low coolant level. Damaged water pump or thermostat.
The most common reasons a Jeep Wrangler is overheating are a coolant leak (water pump, radiator, hose etc.), the radiator fan, or a failed thermostat.
Don`t allow an overheating engine to threaten that convenience. Replace your Jeep Liberty thermostat with a durable component from AutoZone as soon as you notice your vehicle running warm. The signs of a faulty thermostat are a boiling or rumbling noise and the engine overheating.
One of the first things you will notice is the temperature gauge is higher than normal. It may even start to fluctuate frequently. If you notice the gauge is hovering ¾ of the way from the top, then your thermostat is experiencing damage in the form of overheating. This can soon lead to your engine and car overheating.
Look to see if the coolant is swirling/flowing immediately — that means the thermostat`s stuck open. If the coolant doesn`t flow after 10 minutes or so and continues to be stagnant after the temperature gauge indicates it`s hot, the thermostat`s likely stuck closed.
If you notice that the actual temperature of your room is at least five degrees warmer than your desired temperature and your air conditioning system doesn`t kick on, you could have a bad thermostat. If you`re still using a manual version, use this time to upgrade to a smart model.
Start your car`s engine and allow it to idle. Look through the radiator filler neck to see if the coolant flows. At this time, it should not be flowing as your car has not reached the operating temperature to cause the thermostat to open. If you find the coolant is flowing, it means the thermostat valve is open.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Cooling fan unresponsive and other electrical issues – 1995 Dodge Spirit
ANSWER : Hello. It sounds like you have an issue with a bad electrical connection. Most of the time, this occurs from either a bad connection at the battery or a bad negative battery connection. The negative connections at the body and frame come loose or become corroded and cause this. It will take some testing with a voltage meter to find the issue. If you want to have this done, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose the electrical conditions and have this problem repaired.

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Engine cooling fan works fully when it’s cold
ANSWER : Hello. The cooling fan is activated when the temperature of the car reaches slightly above normal operating temperature. If the engine stays cool long enough, the cooling fans will not come on. If the engine gets warm but doesn’t overheat the cooling fan may stay on after the car has been shut off in order to cool down the engine. It is also possible that the coolant is low. This could cause the issue that you are describing with the engine cooling fan. It may be a good idea to have a certified technician, like one from YourMechanic, come out to top off the coolant in your vehicle.

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I had dual cooling fans, the replacement part was a single larger cooling fan. Now I get aengine light about my cooling system. Ho
ANSWER : Hello,
You should check with the person you bought the fan from. I show a listing of a single or a dual fan system. You should replace the fan with the same as what was removed. You should not use the single fan when you were equipped with a dual fan system. The wiring and programming is different depending on how it was made.

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Car jerks when accelerating in reverse & makes grinding noise. Is this a transmission or computer issue?
ANSWER : Hi there. Typically when you hear a grinding noise when you move forward or in reverse it’s usually an indication of a gear fault either in the transmission or another driveline component. If this occurs only when in reverse, it’s likely a damaged reverse gear. It is also possible that it’s a hydraulic fluid issue not supplying enough lubrication or pressure inside the lines to fully open the gear. I would recommend having a professional mechanic come to your location and complete a car is hard to shift inspection, so they can diagnose the source of your issue and recommend repairs that should resolve this problem.

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What Is the Difference Between a Water-Cooled Engine and an Air-Cooled Engine?
ANSWER : There are a few main differences between a water-cooled and air-cooled engine.

Air-cooled engines utilize an engine cylinder design that incorporates cooling fins all the way around the cylinder and on top of the piston cylinder head. These fins draw heat away from the cylinder and radiate away the heat. As the vehicle is being driven, the air is directed over the fins to dissipate even more heat. Some vehicles may incorporate a belt driven or electric fan to blow across the fins to assist in keeping the engine cool. Some engines use the hot air off of the engine to heat the interior of the passenger compartment. Engines that are cooled by air have a harder time maintaining a constant operating engine temperature. This can affect engine operation during colder conditions or extreme heat conditions.

Instead of fins used to keep the engine cool, in water-cooled engines the engine block and heads are cast solid but with internals passages throughout the engine block around the cylinders and over the cylinder in the cylinder head. The engine will utilize a water pump that is connected to these passages on the engine. The water pump can be driven by belt, gear or electric motor. The system has a radiator that is used to radiate the heat away from the water (coolant) that flows through the motor. A thermostat is put into a passageway from the engine to the radiator. The water or coolant temperature is maintained by the thermostat. The thermostat controls flow of coolant into the radiator. As the water pump is turned, the coolant is pumped through the engine. The coolant absorbs and transfers the engine’s heat from the combustion process. As the coolant gets heated, the thermostat will allow the flow to be restricted to the radiator until the coolant temperature reaches a set temperature of around 190 degrees at which time it opens the flow to the radiator. The coolant then flows into the radiator and the coolant heat is transferred to the radiator fins to be dissipated out to the surrounding air like the fins on the air-cooled engine. The radiator has electric or mechanical fans to blow air across the cooling fins. The thermostat opens and closes as needed to maintain a constant engine internal coolant temperature; engine temperature is controlled better that air cooled engines. The coolant can also be routed into the passenger compartment to flow through a small radiator called a heater core to heat the interior of the vehicle.

Some engines may use a hybrid design that uses a water-cooling system mixed with some of the air-cooled engine traits to help keep the engine cool and to lighten the added weight of a full-size water cooling system. These systems may use smaller radiators or thin lightweight radiators and engine designs that have air cooled areas to dissipate heat.

The advantages of air-cooled engines are that they are lighter without the use of radiators, water pumps, thermostats, coolant, or hoses. The disadvantages are that they cannot warm up fast and cannot maintain a constant engine temperature. This will affect engine performance and emissions in climate changes like extreme cold or hot temperatures. A cold engine requires added fuel to run properly.

The advantages of water-cooled engines are that they can warm up quickly and maintain the engine temperature better than the air-cooled design. This helps maintain engine performance and emissions. The disadvantages of a water-cooled engine is the added weight of the engine design along with added weight of the cooling system components like the radiator, water pump, coolant, and hoses.

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Car cabin smells of AC refrigerant at times and now the AC is not cooling after about a month of filling it .
ANSWER : If you have detected a refrigerant and oil mist in the cabin, then an evaporator "area" leak is likely. However, any time there is one leak, the entire system should be pressurized (whether pre or post repair) and tested for leaks in order to ensure trouble free operation. To request diagnosis and repair of your system, please use YourMechanic’s a/c diagnostic service page and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Problems with the cooling system
ANSWER : Hello. It is possible that your radiator is clogged or is beginning to fail. If the radiator cap isn’t holding the proper pressure this may prevent coolant from being pulled up from the overflow tank. I would suggest that you have a certified technician, like one from YourMechanic, complete a pressure test of the radiator cap. The technician should also complete an inspection to see if the cooling/radiator fan motor needs to be replaced, if the radiator needs to be replaced, and/or if the radiator hoses need to be replaced. YourMechanic technicians are mobile and can provide this service at your home or office.

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The cooling mood on my 2007 chevy cobalt came on out of nowhere. I had a guy pour antifreeze in and it was okay until yesterday.
ANSWER : Hi there. Check the coolant level to see if there is any coolant in the radiator. If there is no coolant in the radiator, then fill up the radiator with water and perform a pressure test. Check to see where the coolant is draining out of and fix that item. If you cannot find the coolant leak, then check the engine oil and the transmission oil to see if they are milky. If the engine oil is milky, then the head gasket could be split and causing coolant to go into an oil jacket. If the transmission oil is milky, then the radiator has a split and is forcing coolant into the oil cooler on the radiator.

If the coolant is full and the engine is overheating, then there could be an issue with the thermostat, water pump, head gasket, or radiator cap. Check the radiator cap and see if it holds pressure. If the cap does not hold pressure, then replace the radiator cap. If the thermostat is not working, then the coolant will heat up quickly and either make the engine overheat fast or overheat at a high temperature, but not sever. A burned head gasket or a failed water pump will make the coolant overheat very quickly and cause the computer to perform a shut down. If you need further assistance with your vehicle, then seek out a professional, such as one from Your Mechanic, to help you with your engine overheating and shutting down while driving.

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