7 Symptoms of a Bad Radiator Cap (And How to Test)

The part of a vehicle known as the “radiator pressure cap” contains 2 valves. Its purpose is to contain coolant in the radiator and ensure that the cooling system remains pressurized.

The radiator cap is sometimes also called a coolant cap or an antifreeze cap. All three names refer to the same part. 

Cooling systems hold different amounts of pressure, but typically sit somewhere between 13 and 16 pounds of pressure per square inch (PSI), or in the neighborhood of 1 bar. This pressure is controlled by the radiator cap and needs to remain constant.

Too much pressure will exceed the manufacturer’s specifications for the cooling system, and could cause cooling system component failure.

Too little pressure could cause the coolant to boil off. With little or no liquid around to cool the vehicle, the engine is likely to overheat. 

Below are some symptoms you can look for to determine if you have a bad radiator cap.

Signs of a Faulty Radiator Cap

1) Leaking Coolant

coolant leaking

If the radiator cap is stuck, pressure may build inside of the radiator, which could cause cooling system components to leak or burst.

If you notice coolant near the radiator or the radiator cap, then you clearly have leaky coolant. Check to see if the radiator has holes in it or if the cap looks worn or damaged. If so, then replace the cap.

Related: 5 Causes of Coolant Loss Without Visible Leaks

2) White Streaks on Radiator

white residue on radiator

When coolant leaks out of the radiator filler neck and dries, it often leaves white streaks behind. While you may not notice coolant leaking from under the radiator cap, look out for these white streaks. They may tell you the cap is leaking under pressure or intermittently. 

3) Overflowing Reservoir

coolant leak

Coolant goes into the reservoir tank as it expands. The radiator cap releases the extra pressure by sending some coolant into the overflow tank.

If you have a bad radiator cap, the coolant could get released too quickly and cause the reservoir to overflow. While you’re in there, check to make sure your coolant overflow tank is working properly.

4) Radiator Hose Collapses

collapsed radiator hose

You may have a bad radiator cap if the radiator hose collapses. The vacuum won’t be released by the radiator cap properly and it will cause the radiator hose to collapse during the cooling down period.

If this happens, inspect the cap to see if there is any damage. If there is, replace it immediately.

5) Radiator Hose Bursts

radiator hose ready to burst
radiator hose ready to burst

If pressure in the cooling system is too high, you are likely to see one or more hoses start to spray coolant all over the engine bay.

Most of the time the pressure isn’t high enough to rip the hose in half. You will often see a pinpoint leak that only sprays coolant when the car is warmed up.

A hose with a small hole may actually seal just fine when the car is cold. As you drive, pressure in the cooling system will build. The pressure will eventually be enough to force coolant through the tiny hole and your car will slowly lose coolant.

In this situation you’ll likely notice a leak on the ground or in the engine bay when you reach your destination, but not when you start driving. Check to see if your overflow reservoir is draining slowly over the course of a few miles. This may give you a hint that this is the problem.

6) Overheated Engine

engine overheating symptoms

Leaky coolant or air in the cooling system can lead to an overheated engine. If you notice your engine starting to steam from getting too hot, don’t look under the hood unless you’ve turned the engine off. Then, let the engine cool for some time before popping the hood. 

That way, the engine can remain cool as you check it out. If there is coolant fluid near the radiator cap, there could be damage to the pressure cap. Check for that and replace as needed.

7) Air Inside the Cooling System

When your radiator cap does not seal properly, air could make its way inside of the cooling system. This will cause air pockets to get inside of the heater core, thermostat, and radiator hoses.

As a result, the engine will start to overheat because it cannot sustain a temperature that is consistent.

How to Check the Radiator Cap

Warning: Never open the radiator while it is hot! Allow the engine to cool completely before opening the radiator.

The radiator is under high heat and pressure. Attempting to open a hot radiator will cause hot steam and coolant to spray out and is very likely to burn you.

Inspecting the Cap

Before you get too deep into the diagnostics, double check that the pressure indicated on the radiator cap matches the cooling system pressure specified by the manufacturer. You can find this information in a repair manual, factory service manual, or online.

Visually inspect that cap to make sure the spring moves freely and there is no debris or corrosion under the cap. 

Pressure Testing the Radiator

If you have a radiator pressure tester, then you can inspect the cooling system on your own. This may help you find leaks or determine if the radiator cap has gone bad. You may also be able to rent this tester from your local auto parts store.

To begin, pop the hood and find the radiator. It is usually located right in front of the vehicle’s engine. Now remove the radiator cap by pushing it down first and then twisting it counter-clockwise.

Take the cap adapter and screw it onto the pressure tester’s end. Keep screwing until you cannot screw it anymore. If you don’t know what the cap adapter looks like, check the label of the pressure tester’s packaging and see if it shows it on there. You can also look it up on the internet as well.

After you’ve secured the cap adapter onto the pressure tester, screw the other end of the cap adapter onto the radiator filler neck until it is tight.

The pressure tester should now be sealed against the radiator. If it is not, you may not be using the correct adapter for your specific radiator.

Using the pump handle, start pumping the tester until you reach the pressure indicated on your radiator cap. See if the gauge can store the pressure. If the pressure begins to fall and you’re sure you have a good seal against the radiator filler neck, you have a leak in the cooling system.

See if you notice any external coolant leaks while the system is pressurized, as they will be easier to find this way. Any leaking components will need to be replaced.

When you’re done with your pressure test, unscrew the radiator cap adapter slowly so coolant doesn’t spill everywhere. It may be a good idea to have a pan or bucket handy to catch any that overflows. Top up any coolant that was lost, and clean up any coolant that has spilled onto the ground.

What Does the Coolant Cap Look Like?

radiator cap

The coolant cap is typically made of metal and sits near the front of the engine bay. Sometimes the radiator cap is oblong in shape, but on some cars it is round. Since the radiator is pressurized, you will often see a warning label on top of the radiator cap that instructs you not to open the cap while the engine is hot.

A radiator cap is different from an overflow reservoir cap. An overflow reservoir cap is usually made of yellow plastic. A simple plastic cap is used on reservoirs that are not pressurized. 

Please beware that some overflow reservoirs are pressurized on certain vehicle models. If you aren’t sure if your overflow reservoir is pressurized, check the owner’s manual before you try to open it with a hot engine. If you have a metal reservoir cap or your cap screws on, chances are you should wait for your engine to cool down.

Bad Radiator Cap or Head Gasket?

When your car overheats, sometimes it is hard to tell if you have a bad radiator cap or something more serious like a blown head gasket. To check to see if you have a blown head gasket, you can do a leak down test.

A leak down test shoots compressed air into each cylinder via the spark plug hole (after removing the spark plug). The head gasket is designed to keep the combustion chamber completely separated from the cooling system. If any air leaks into the cooling system, you will know you have a head gasket leak.

Radiator pressure tests can often tell you if you have a bad radiator cap. Once you’ve pressurized the system, you may notice coolant leaking at or near the radiator cap. This can happen if the cap itself has a bad seal.

Other Cooling System Problems (Bad Thermostat)

If you notice that your radiator cap is not getting hot even after the engine has been running for a while, you may have a problem with your thermostat. When a bad thermostat is stuck in the closed position, engine coolant is only able to circulate through the engine block and cannot make its way into the radiator. This could leave the vehicle with cold coolant in the radiator, even though the engine overheats.

Thermostats are typically straightforward to replace but require opening the cooling system. Any time you let air into the cooling system, this air needs to be bled out. Air pockets inside the engine can cause hot spots that lead to intermittent overheating.


70 thoughts on “7 Symptoms of a Bad Radiator Cap (And How to Test)”

  1. When the engine is cold and filler cap is removed, there is no coolant above the cooling fins. However, the overflow reservoir is at a normal level and the engine runs at the same temp as always. This is a Honda Pilot 2003 which has some unique features, but I’m going to guess there should always be water between the cooling fins and filler cap?

    • Yeah, I’d fill the radiator. The level should be up to the top right next to the cap. Any excess will overflow into the reservoir.

  2. Hi Sean!

    I was driving my 2005 MDX when it quit and wouldn’t start. Checking under the hood smoke/vapour came out from the front of the engine on the passenger side. I checked the engine temp display and it was within limits. Since I now had an engine indicator light, I checked the codes and got “Catalyst Efficiency Below Threshold (Bank 1)” and “Engine Coolant Temp Circuit Input” (I think it was low input but I could have skipped a line and was actually high input). Once cooled, the MDX started and was run only to load and unload it off a flatbed and it got towed to a shop. I mentioned to the mechanic what occurred and that I suspected a blown hose.
    The mechanics says that when he fills the radiator, that the liquid goes into the overflow reservoir which is a sign of a blown head gasket, that the radiator was low/empty causing the engine to overheat.
    Now, wouldn’t a bad radiator cap cause the liquid into the overflow reservoirs also? With the engine codes displayed, and the fact that I didn’t drive the MDX while an overtemp was displayed, could it just be that a hose leaked some radiator fluid and the engine stalled before the condition reached an overheat, but still ran hot for a while causing the radiator cap to fail? How can I verify what is actually required as the cost of changing the head gasket and associated cost of correcting any damage to the cylinders/valves/rings/head has been quoted as $3,000 to $4,000. This is in comparison to changing the radiator cap and a hose. Your knowledge and expertise with this is much appreciated.


    • A leak down test should tell you definitively if you have a failed head gasket or not. If you see bubbles in the cooling system while performing the leak down test, you have a failed head gasket.

      I’m not sure I understand what the mechanic said about liquid going into the overflow reservoir when you have a blown head gasket.

      • What the mechanic is saying is that compression pressure from a cylinder could be entering the cooling system and pushing the water out, into the expansion tank.. This should show up with the engine running and cap off.

      • I was just told this too, mechanic said head gasket as coolant going into the overflow reservoir.. have replaced radiator, thermostat and still getting hot.. Subaru f’ster

  3. Hi Sean,

    I have a 2011 Infiniti G37x. I was having trouble getting AC of heat into the cabin. Sometimes with the on AC it would fluctuate cold, then warm, then cold, etc. My wife borrowed the vehicle one day and it overheated. After inspection I found the lower hose at the firewall was ruptured. I fixed that hose, but after filling with the coolant mix and running the car up to warm, and although the gauge seems normal and there was no overheating, I noticed the coolant level was down almost all the way after I shut it down. I added enough to fill up both the radiator and overfill, and started it again and let rum for about 20 minutes. Gauge remained normal, but upon inspection again, no coolant in the radiator or overflow, and none visible underneath the vehicle. I checked the oil stick and no coolant was visible or by smell. Also there is no smell inside the cabin. The radiator fans are engaging, and there is no water pump squealing. The ONLY thing I noticed was the upper rad hose did NOT get hot after 20 minutes, (which I assume could indicate a bad thermostat), but where is the coolant going, because it’s not under the vehicle ? IDEAS ?

    Thank you for taking the time to answer, Don

    • If there are no leaks and coolant is disappearing, verify that the cooling system is fully bled of air.

      Every car has different nuances as far as properly bleeding the cooling system, but the principle is this: make sure the fill point is at the highest point in the cooling system, pour coolant into a funnel attached to the fill point, let it idle until the thermostat opens (best to wait until the fans kick on in most cases), turn the car off and cap off the fill point.

      The fill point will either be the radiator filler neck or the overflow reservoir. Some cars have a dedicated fill point that is the highest point in the cooling system on level ground. Do a bit of research on your specific vehicle and you may find a few tips and tricks.

      If you run through this process and any of the following occur, you have a cooling system problem:
      1. Car overheats
      2. Fans do not kick on (make sure you wait long enough, it may take a while)
      3. Upper and lower radiator hoses are both cold (indicates thermostat has not opened)

      It will take a long time for the vehicle to come up to operating temperature, so be patient and make sure you don’t stop bleeding until at least this point. If you continue to see air bubbles well after the fans kick on, you may have a head gasket or intake manifold gasket leak. A leak down test or borescope camera can help you verify this.

  4. Hi Sean. I have replace the radiator cap, checked underneath vehicle for water drips etc, checked dipstick for indication of water in the oil

  5. Hi. I have a Mutsubishi 2.4 petrol double cab pickup. It is overheating and blowing steam at the radiator cap. Nothing has changed in the water level of the expansion tank. Also, the temperature gauge remains within its normal range. What am I missing here? Thanks in advance

    • A Subaru losing coolant without any apparent leaks makes me think you may have a failed head gasket. Take a look at this article and see if it helps: https://oards.com/subaru-head-gasket-problems/

      You may want to perform a leak down test to see if you do in fact have a head gasket leak. A leak down test with failed head gaskets will show bubbles coming out of the radiator or coolant reservoir. Don’t open the radiator cap while the car is hot.

  6. My needle will fluctuate from a little above the middle line and back to normal until it finally overheats, my cap has flown off once from the pressure being so high. I’ve replaced the thermostat and flushed the radiator. Also made sure my fans were working. Could it be the cap?

    • Pressure increases with temperature, but a cap that holds too much pressure wouldn’t cause your car to overheat; something else is preventing your car from cooling correctly. Check your radiator fans to make sure they are running and make sure your thermostat is working. I would also consider replacing the radiator cap because it sounds like it’s holding too much pressure. However it’s possible the radiator filler neck was damaged by a past incident and this is causing the cap to blow off at or below the correct pressure.

  7. My 2019 Nissan Pathfinder keeps over pressurizing the cooling system and blowing coolant out where ever possible? I bought it a few months ago and Nissan said I had over pressurized it by adding fluid. But I have not done anything. And I have had it back after paying to replace a blown upper hose only a few days and I can smell burning coolant Again and I seen some fresh collections on the engine??? Help

  8. I did not know that caps are this important until my technician told me. To sum up everything he said. All car parts play a very important role. So from then on, I made sure that when something is a little bit different, I will immediately take my car to him.

  9. I drive a Hyundai. I was headed to work and I came to a stop and all of a sudden, steam started coming from engine. Opened the hood and the radiator cap was not on the radiator There’s no leaks, and no mixture in the oil. The cap was brown and rusted. Advice???

    • At the very least, replace the radiator cap, top off the coolant, and burp the radiator. You should also check to make sure there is no damage to the the radiator.

  10. Hi there, I have a 2007 Hyundai Tuscon I’ve taken great care of, she had a full tune up in March, with scones head gaskets replaced, and recently had some more work done. I was checking the oil 2 weeks ago and noticed the coolant reservoir looked a lil low. I took it to a local oil shop and they agreed, shot some water into it and charged me lol. They said to keep an eye on it, but honestly, I checked a day later and I think bc of the water, it was too transparent so I had difficulty figuring out where the level sat. I waited a bit and today I could see the coloring and its just at the low line. I spent $22 on the 50/50 mix and before I add it, I just want to check if I’m doing the right thing. I’ve seen no leaks, smell nothing, I’m not good at examining auto parts but I’m guessing at best, it could be the radiator cap. I’ll check that in a few mins. When a check engine light diagnostic is ran, only a gas cap error shows these days. It’s been on since I bought a new gas cap. Thanks so much!

    • Some cars leak a little bit of coolant over time for a variety of reasons. This could be out the overflow reservoir, the reservoir hose, radiator cap, coolant hoses, or into the engine from a head gasket leak. Top it off to the full line and keep an eye on it for now.

      Check the coolant every day to see if the level drops. If it drops, try to figure out where it’s coming from. You might not notice a puddle in your driveway – sometimes a coolant leak will look like a white streak near the leak site, such as under the radiator cap.

  11. the radiator draws from the tank but don’t return the coolant. The engine is hot and there’s pressure in the radiator, but coolant do not overflow into the tank. Does a bad cap do that? The pressure actually burst the plastic part at the top. It’s a 2001 Chevy tracker.

    • Yes, a bad cap could absolutely do that. If the valve in the radiator cap doesn’t open at the right moment to bleed the excess pressure, you can damage the cooling system as it will end up holding more pressure than it was designed for.

      When you buy a new cap, make sure it has a pressure rating that is designed for your vehicle. For instance, don’t put a 16 psi cap on a vehicle designed for 13 psi.

  12. Hi my name is Dennis Matsha driving a Toyota Corolla 2002 model I just overhaul the engine February this year and suddenly the car is overheating, cause when i start the car the coolant cap pops up and I bought a new thermostat cause the heater was not blowing hot air. What seems to be the problem?

    • Have you tried changing the radiator cap? Make sure you have the correct pressure cap. If that doesn’t help, more troubleshooting of the cooling system is necessary to pinpoint the problem.

    • I would actually take a look at the thermostat. If the thermostat is stuck open, the engine would have a very hard time warming up to and maintaining operating temperature.

  13. Hi my name is Scott and I have been working on these old Chevy motors since I was old enough to hold a wrench but this one has got me stumped it is running around 260 degrees I’ve changed thermostat I put a new clutch fan plus a small electric fan it is building up psi the hose never hose soft like it should when the thermostat opens I haven’t changed the cap but in my experience the cap will cause the hose to collapse other then checking the heads and gasket I am at a lose please if anyone has some kind of solution please feel free to let me know thank u so very much in advance

    What would make the engine build up to much psi other then a head problem

    • It sounds to me like you have multiple cooling issues going on, which is making this harder to test. If I were you, I would start with the following:

      1. The higher the heat, the higher the pressure; figure out why it’s running at 260 degrees first. Most thermostats open around 160-180 degrees. If your thermostat is opening in the 160-180 degree ballpark, the next thing I’d do is a leak down test. If you get any air bubbles coming out of the cooling system, that’s a textbook blown head gasket.
      2. Figure out why the pressure is so high. I think this issue may be related to the root cause for point #1 above. If the radiator cap is old, I would try replacing it. Make sure you replace it with a cap that holds the correct pressure for your cooling system. You should be able to find this pressure rating online or in a repair manual.

    • Hello Scott,

      When looking at your cooling system you need to decipher when is overheating. Is it overheating just while idling or while driving, and/or all the time.

      There could be many reasons that it could be overheating but knowing when it overheats gives you a direction.

      If you have a bad radiator cap then it could suck in air push it to your overflow and cause a flow problem with air pocket…. Look at the basics and the symptoms, write down when and what happens, and follow the trail…you will find it.

      Also, newer cars, not sure year, make and model of yours, but newer cars are made of a bunch of plastic parts and housings that will only leak as they get hot with pressure and swell and you will never see it.

      Do you have air conditioning and heat when you turn them on? If you turn on your heater and you have no heat you have a flow problem air pocket or a component failing.

      Or the cooling fans turning on when they are supposed to on newer models. Does the AC fan turn on and or the cooling fan turn on, on newer application. Of course older models have fan clutches, it also supposed to lock up and help the water pump circulate at certain temperatures. But that is with the fact that your radiator is good and cooling system components are in check, again known factors.

      You have to have flow. You have to have known factors in order to diagnose. Make sure you don’t have exhaust gases going through your cooling system by doing a chemical test at a part store for confirmation to make sure there’s no damage. And I have seen people put the thermostats in wrong, not saying you did this, but you have to have the air release or that needle on top of the thermostat facing the 12:00 position, you may have gotten a defective thermostat or wrong application, buy a failsafe thermostat then if it fails it will stay open and not overheat

      Make sure no air is getting into system and it is burped properly, if burped, and Air is still getting into system then that needs to be tracked down.

      Could also have clogged exhaust, look at exhaust temperature, if you have catalytic converters, could be having back pressure on engine causing stress on motor causing overheating

      If your vehicle is overheating just while idling then look at those components such as the fan clutch and of course radiator application if it is large enough, water pump could be defective, and even your idle if too low or too high, and even timing of the motor setup. You have to have flow and I got stumped when I had a plugged radiator and heater core due to berries from a tree somehow getting into system. I went to larger core radiator and blew out heater core with air hose to clear.

  14. It’s good to know that coolant fluid near the radiator cap could mean there is some damage to the cap. Last night I noticed that my engine was getting overheated in my old Ford truck and I’m worried that it could do some real damage. I’ll have to check it tonight and make an appointment to get it serviced at a car repair shop as soon as possible.

    • I recently bought a 2000 Honda Accord for 1200 dollars ..The lady did not say it had to have a brand new Radiator put in it ..She gave me the new one and my Cousins husband changed it..I drove it to and from the store yesterday it did not show no warning signs of over heating or anything….I also have an issue to her when I first bought the vehicle after we went to DMV together to make the inspection and purchase she told me nothing at all was wrong with the car..When I was driving home myself after the purchase I found 5 bottles of anti freeze the one kind as to where it’s mixed with water..Can you explain to me your professional opinion why she had possibly all this anti freeze in the vehicle..Of course now she won’t return my calls because she knows she sold me a car that was doing something she did say the other night when I spoke to her nothing was wrong with it except for the Radiator needed to be changed and it was but the hoses needed to be connected so she came to Walmart to help me tighten them because my cousin’s husband didn’t all the way and after that she will ???? not of course return my calls…..What’s your professional opinion as to why she has all this Anti freeze in the car I bought?..I need to know a machanic opinion?

  15. hi…i have a 2007 pt cruiser. top radiator hose is hot across engine and
    hot still at the thermostat housing but rad cap up top is cold or cool.
    I have intermittent warm heat at best.
    temp gauge is constantly running below first cool tick line….no overheating
    at all…

      • Make sure you don’t have any air in the system. If you bleed the radiator and find more air later, I would figure out where that air is coming from so it doesn’t develop into a bigger problem down the road.

      • I have this same issue on a 2005 pt cruiser turbo. The bubbling sometimes while running and almost always when i shut it off. Replaced the thermostat, which was frozen appsrently. Checked the fan with a wire tester, that wasn’t coming on, so that’s now manually done everytime I turn the car on. Seemed to help the car drive better the first day then i noticed it was driving weird again. The bubbling has been consistent since I got the car 5 mos ago. It only overheated twice once on a 3 hr trip. Also there is a crack in the overflow tank. But with fan on, no longer constantly putting water in. I’ve been burping it to make sure air not in line. Few days ago I was told because thermostat isn’t going up but it’s bubbling is a pressure issue. Now my heater core just went, but I’m so lost on how to fix the bubbling. Could the overflow crack be the pressure issue? I read the other turbo needing that hose replaced and will do that next. Please any help is appreciated. They’re so ugly noone I know had any experience with them and the setup under the hood is a pain in the *ss to deal with. ANY ideas please help

      • Those overflow tanks aren’t pressurized, right? I don’t think that’s the problem.

        Sounds like you need a thorough inspection of the cooling system. There may be multiple problems at this point because the overheating issue wasn’t addressed quickly. I’m not really sure what the root cause is.

  16. Hi, I have a 2002 Toyota Hiace. The overflow tank overfills and liquid does not go back into radiator after cooling. Have had the pressure test, and my mechanic put in Chemi-Weld to rectify this problem. He talked Head Gasket issues and we are hoping not to have to go this route. I replaced the radiator cap and wonder if buying a cheap one was a bad idea. Should I get a genuine one from Toyota? The mechanic also said I had a tiny leak in my overflow tank. Would replacing this do the trick? Get both a new cap and overflow tank?

    • I would always go OEM on something like a radiator cap. If it’s not sealing, it will prevent flow back into the radiator. The leak in the reservoir can also be causing this since you need vacuum between tank and radiator to function properly. Check the coolant overflow hose for a leak as well.

  17. Please I have a Toyota Matrix 2003. I have being experiencing overheating lately. The mechanic said it was a blown gasket, he changed it and washed the radiator tank. At a low of 1000 – 2000RPM the temperature is normal but from 2200-3000RPM the temperature goes high, on the high way the water heats up and boil, which evaporate through the expansion tank outside. Please what can I do because I’m out of ideas.

  18. Need advice. I was driving my honda accord 1999 down road and saw steam. It was a upper radiator hose with a tear in it. The heater went out.

    I replaced the upper hose. I filled radiator up and overflow to min. Heat came back.

    Now I see steam coming up. I’m not sure if it is from the antifreeze from the hose blowing or new issue.

    What would cause the hose to tear like this? I replaced the radiator, the cap and hose about 2 years old.

    How can I test to see if it’s the cap? I dont have any specific tools for this.

  19. Happy New Year. Appreciate your work in helping us with a good article and post. 2008 PT Cruiser Turbo. Radiator began leaking last summer. Had it replaced. Come winter, I found little heat coming into the cabin. The fluid lines into and out of the cabin show 195+ deg temp, so not the heater core. Have refilled the radiator with air removal via the air bleed valve, have replaced the thermostat and the radiator cap but the unusual problem remains that engine temp takes a long time to get to the mid (normal), then at highway speeds the temp actually begins to drop towards the quarter mark. Will get some heat into the cabin after like 30 mins of driving. In street driving the radiator fan cycles on and off as normal.

    Now, after a few weeks the CEL has come on with a code of P0128. Only thing left is the coolant temp sensor which is kind of hard to get to but could probably be done with removal of the left headlight, which’ll be a lot of work.
    Thoughts, please? Thanks in advance.

    • Found the information at Autozone’s Repair Guide:
      2008 PT Cruiser Coolant Temp Sensor Replacement
      Turbo Models
      Before servicing the vehicle, refer to the Precautions Section.
      Disconnect the negative battery cable.
      Partially drain cooling system below level of ECT Sensor.
      Support engine from below with a jack stand and piece of wood
      Remove upper torque strut. (One 18mm and two 15mm and wiggle the mount out)
      Disconnect ECT sensor electrical connector.
      Remove ECT sensor.
      To install:
      Install ECT sensor. Torque sensor to 168 inch lbs. (19 Nm).
      Reconnect ECT sensor electrical connector.
      Install upper torque strut.
      Fill cooling system.
      Connect negative battery cable.

      • Update:
        Turned out that it wasn’t my Coolant Sensor either.
        Then, while looking for the intake air temp sensor I discovered that the long black thick goose-neck hose that goes from the top of the air filter box to the turbo air intake was totally rotten at the bottom neck and was almost separated at that point.
        So, for any car that is over 5 years old I’d recommend checking the air feed hose first, for temperature issues.
        Heat around the engine seems to be enough to disintegrate the material of these hoses.

  20. I have Toyota Camry 2006 and my car’s radiator is going dry and every 2 days I need to fill coolant. I visited radiator mechanic but he didn’t find any leakage but auto mechanic suspected that it may be a gasket issue and the coolant is filling into the engine. We checked engine oil also we didn’t find water in it. Can you suggest me what should I do I’m just going to change the cap immediately after reading the above symptoms.

  21. I have a 2001 chevy cavalier. I replaced the thermostat my car started to run hot finally got all air from line and it idles and drives 195- 197. When I turn the key off antifreeze goes out the recovery tank over flow hose. Can any one please tell me why??

  22. Hi, my 94 honda accord just blew the cap off going down the interstate. So what caused this? Do I have a bad radiator cap or is my radiator going bad? Need to know if I put water in it can I still drive it home?

    • It’s likely a faulty radiator cap. It’s job is to open and purge excess coolant to the overflow tank when a set pressure is reached. If it’s not doing its job, that pressure has nowhere to release so the cap itself pops off. It’s possible (but highly unlikely) that it’s a blown head gasket but in my mind, replacing the radiator cap should fix your issue.

      • Hi Kevin I opened my radiated on the weekend so I filled back up coolant vx commodore. By accident but know it’s making a crackling sound do I just reales pressure or by a new radiator cap not sure Shane

  23. My radiator blew. Replace it with a new one plus new thermostat. Started 2.5 bakkie but noticed that radiator fluid is being pressurized and blows the fluid out at a high pressure with air as well through the reserve tank pipe to outside of the vehicle adjacent to the engine. Please advise

  24. My 1997 Buick Le Sabre consistently loses coolant. Car runs at 100 120 degrees. On Vent, you can get slight amount of warmth on passenger side. Driver side cold.

    • Need to figure out where the leak is coming from. Most common areas would be the radiator cap, a radiator hose, the radiator itself, or the thermostat. Worst case is a leaky head gasket.

  25. my car is a Subaru Impreza 2003 model.
    Radiator dries up every few kilometers.
    Radiator cap suspected.
    What is the right radiator cap?

    • Any auto parts store or dealership will be able to tell you which cap you need. Make sure you don’t have a leak in the radiator or overflow tank.


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