Car keeps overheating, the cap will not fit on the radiator

Car keeps over heating , first the thermostat was bad so I replaced that first , ran good for a while now it over heats again, my cap leaks and I've tried 9 different ones now and can't seem to find the correct one the radiator is 2 years old at most but seems like a cheapo one some one threw in. I did compression test and came back good, my fan works and comes on when it gets warm , I let it run with cap off and the coolant level fluctuated and bubbled periodically so I think the water pump is ok , I can't seem to fix the issue could the cap be the root of the problem, I've

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Overheating Engine

If the cap can`t maintain the correct pressure for your vehicle, the engine will start to overheat. An overheating engine could also be a symptom of air pockets within the cooling system. If the radiator cap doesn`t have a good seal, air can make its way into the system, creating little pockets.

Overheating can be caused by a: Cooling system leak – This is the most common cause for a car to overheat. The radiator, hoses, water pump, head gasket, and thermostat housing are all components of the cooling system, and all can be susceptible to leaks.
When the radiator cap is bad, your car is likely to overheat, which can cause more serious issues down the line. Essentially, the radiator cap would no longer be able to correctly maintain the internal pressure of the system. Drastically increased pressure could cause certain parts of the cooling system to break.
Coolant leaks and engine overheating are usually caused by a failing water pump. Automotive water pumps are designed to leak coolant through weep ports as a warning that they are failing. Aside from overheating, a distinctive grinding or whining noise caused by a bad bearing is also a symptom of a bad pump.
Why is my car overheating but it has coolant in it? It could be that the coolant concentration is not correct, or you may have a bad thermostat, a failed water pump, broken drive belt, or a bad radiator or radiator fan.
Bubbling indicates rising air pressure in the cooling system, which is a sign that the flow of liquid is blocked by a pocket of air. One of the most common causes is a blown head gasket, in which the air pressure inside the cylinder heads is transferred to the cooling system.
And, while it might be tempting, make sure you don`t open the radiator cap while the engine is hot, warns Seyfer. This is because the hot coolant can cause severe burns. Seyfer adds that leaving the system closed until it fully cools down may actually be better for the engine, too.
Leaks. The most common cause of radiator leaks is leaky hoses, but you can have leaks in the radiator itself, too, which can be a bigger problem. The coolant continually running from your radiator to your hot, running engine and back again creates a lot of pressure.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I had my radiator replaced also my lower radiator holes replaced and my car keeps shaking really bad when the car is still
ANSWER : The shaking could be the result of a number of issues, including the engine having a misfire (not firing on all cylinders). The radiator replacement would not have created this condition. The vehicle should be inspected in order to diagnose this issue. A YourMechanic certified mechanic can come to your home or place of business to perform a car is shaking or vibrating inspection on your vehicle.

Forgot to put radiator cap on car now car keeps running hot
ANSWER : Depending on how long the radiator cap was off for, this may have cause the coolant to leak or evaporate resulting in the engine overheating. If this continued for a period of time long enough, this may have caused a cylinder head gasket to be damaged. A blown head gasket may cause a number of different symptoms. A head gasket that fails between cylinders will generally cause a misfire and potentially compression leaks from one cylinder into another. Low compression will eventually result in a rough idling engine. When the head gasket fails between a cylinder and the coolant port, coolant may leak into the cylinder causing it to be burnt with the fuel charge in the combustion chamber. This often results in misfires on startup, especially after the engine is run, turned off and restarted and in some cases may result in the engine not maintaining enough cylinder compression to even run or start. This type of failure may not always show with a compression test. I would recommend having an expert from YourMechanic come to your location to properly diagnose the symptoms you describe.

My heat in my car stopped working two days ago and now my car is overheating. I put antifreeze in my car and it’s still overheating 2006 Pontiac Grand Prix
ANSWER : Hi there – you may have 2 related events here, a coolant leak, and a problem with the heater system. The current issue may be air inside the cooling system, which can cause overheating, and a lack of heater function. The lack of heater function could have 5 causes: the engine is not getting up to correct temperature (center of the gauge) due to a malfunctioning thermostat, the heater control valve is not letting hot coolant into the heater core, there is a restriction in the heater system that is preventing adequate hot coolant flow through the heater core, the heater fan is not working to transfer heat from the heater core to warm air for the passenger compartment, or the air blend doors inside the heater are not working properly to route warm air to the desired vents. I would recommend a heater system inspection](https://www.yourmechanic.com/services/heater-is-not-working-inspection) by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

car is overheating and leaking water and anti freeze
ANSWER : Coolant leaks can occur because of cracked hoses, leaking gaskets, faulty water pumps, or damaged radiators. When the coolant level goes low, the engine will start to overheat due to the low coolant level. I would first recommend giving the cooling system a visual look over. If it is not obvious where the coolant leak is coming from, I would recommed having the cooling system pressure tested in order to determine the leak source. If you would like to have your cooling system pressure testedcoolant is leaking inspection, consider YourMechanic, as a certified technician can come to your home or office to inspect your cooling system.

Just had radiator replaced in March but car overheated today. Fluid level fine – what could be happening?
ANSWER : It sounds like there may be a problem with your cooling fan. If it is not working, the car can overheat when stationary. A quick way to check this is to turn on the air conditioning. The cooling fan should be running whenever the air conditioning is on.

If the fan doesn’t turn on with the air conditioning there is a problem. Another possibility is that the water pump impeller has failed, so the coolant is not circulating. If the coolant is not circulating, it cannot be cooled down by the radiator. We notified our customer service team about your issue, and they will get in contact with you soon about your overheating problem. You can also give us our team a call at 1-888-341-3994. They we will help you solve your problem.

Expansion tank cap keeps cracking and the car overheats in stop and go traffic.
ANSWER : It is impossible to tell without doing some further testing. Your issue may be caused by a compilation of several different components. A run of 6 months is pretty good to not have any issues. Slow traffic can cause the engine to heat up quickly. High heat leads to high pressure which can cause the cap to fail. When you say that "a bunch of work" was done, what exactly was fixed? What wasn’t?

The radiator cap is meant to relieve high pressure situations, and it may have failed to vent. The fan is critical for the decrease in temperature when sitting in traffic. When the vehicle is moving, the air coming through the grill works to help cool the coolant in the radiator. The fan is in charge of this task when there is no air flow.

I recommend having a certified mechanic, such as one from YourMechanic, come to your location to determine why the car is overheating.

Replaced alternator on car 2 times each time shows it’s charging 14v let car run for a little bit then test drive and car voltage
ANSWER : There are reports that the replacement alternators will not communicate with the engine computer and will not charge correctly. I recommend using only the manufacturer approved replacement part. It can be new or remanufactured but approved for use in the vehicle. Some lower cost alternators on the aftermarket will have charging problems since they will not communicate with the ECM on the vehicle and will stop charging.

07 nitro overheating on me… water pump? thermostat? radiator cap? best way to diagnose
ANSWER : Hello. There can be a few possibilities that can cause the overheating condition. Have the radiator and pressure cap tested to make they hold pressure. Look for leaks at the water pump. The pump will show leak coming front the front of motor and will drip off of the crank shaft pulley areas. If pump is leaking, then replace the pump and thermostat.