Not all cars have radiator caps, checkout our full video for more information!! kzfaq.info/get/bejne/lb2hksJmz8CVl4E.html

Some cars have completely sealed radiators..... so you have to fill it via the overflow tank.... sooooo

Important to note over time it will pull coolant from the bottle into the radiator and back as the coolant expands and contracts.

Glad for the info, but please stress the safety of opening that cap under pressure more. Seriously guys do not do it. You’ll burn yourself with a geyser of boiling coolant all over you.

You HAVE to make sure the engine is NOT HOT!! Otherwise you will have 3rd degree BURNS!

Cold engine, remove cap, start engine, warmup with cap removed, wait for thermostat to open, run heater full force, then add fluid. Replace cap. This prevents air pockets from forming.

“Budget Mechanic “ , says it all

In almost all modern cars, if the reservoir has at least minimum fluid in it, the radiator is full. There is no need to open the radiator cap. Adding to the reservoir directly is the proper way to add coolant. You can open the cap when everything is cool if you’d like, but it will be full with no room to add coolant.

Wrong. A low radiator fluid level will be replenished from the reservoir over a given heat cycle or two. Go drain 16 ounces out of the radiator petcock and get the car hot. Turn off the car. Fill the reservoir to the full mark. Next morning reservoir will be empty because it replenished the lost fluid.

How is the blinker fluid level?

Yes, you put the coolant in the overflow. Because, when the engine cools off , if the radiator or the cooling system is low, a vacuum is created and coolant is sucked from the overflow into the engine, next time , you fill rhe overflow again. Unless, you have a leak in your system, then you have bigger problems than low coolant.

Thanks for the short and to the point video. This is all I needed answered.

This man does not understand “solid” fluid systems. Many new vehicles don’t have radiator caps(or they aren’t easily accessible) the reservoir is needed bc the coolant expands as it gets hot and then contracts again when it cools. So the coolant can expand out into the reservoir then when it cools off again the coolant shrinks, because the system is closed this creates a negative pressure in the coolant system which pulls the contents of the reservoir back into the radiator until the pressure is neutral again. Notice how there is a hose connected to the bottom of the reservoir. Adding coolant to the reservoir is just fine. It will not cause an issue. Any air that happens to enter the coolant system will be “belched” out when the system gets hot again because reservoir is vented at the top.

I have a 2014 Outback. While filling the windshield wiper fluid container, earlier today, I happened to look at the coolant level. It was completely empty. I couldn't figure out why my car had not notified me that I was out of coolant. This video just explained that. What a relief!

Some cars don't have radiator caps

To further specify cool, make sure your vehicle hasn’t been running in the past 6 hours lol I’ve had too many friends get burnt up from opening the radiator cap when it’s not cool enough yet

I own three cars right now, none of them even has a radiator cap. This video is good advice if your car is from 30 years ago or older.

The reservoir overflows tank on my car has the radiator cap on it and it goes to the radiator. The water pump actually empty’s into the overflow. That’s how it is on my dodge challenger.

Thanks to youtube learning, the real mechanic shops are getting more work. Keep it up 👍👍 keep posting and thank you

Good luck finding the radiator cap. Notice the cap on the reservoir - it's labeled in PSI. The bottle is the radiator access.

Depends on the vehicle, some only fill up from the resivore but if you have a place in your radiator to fill up the radiator, you better go into the radiator bc on those said vehicles, the resivore is only there for over flow

Thanks bro. That’s exactly what I needed to know.

My 2014 ford focus i have to top it off at the reservoir. Except my 2003 dodge dakota 3.9 this truck is a beast and in my book the best of the best . If you maintain it.

It's not a over flow it's an expansion tank jeez

Fill those over flow tank forgot about this guy. After you drive it getting hot and after it cool down it creates vacuum suck back cooling back to its system

The video is correct. Open the radiator cap (only when engine is cold), fill to full, then watch fill line on reservoir, fill until it's between min and full (being conservative), and you're good to go. Be sure to use the right coolant, Toyotas should be red, but check the color and documents of which coolant, the newer versions G12+ and G13 don't have much problems mixing with old versions of coolant, to be safe flush ALL old coolant out, preferably run with pure distilled water once and then flush it ALL again, refill with new, premixed coolant, check the freezing point should be around 40-50 minus C.

Damn this is super helpful!!

I don’t know much about cars. Thank god I read the comments 😅

Okay so 1 does it really matter? And does the reservoir tell you when you need coolant? Or no because I have a thing of coolant but not sure if my car need any at all

A Properly functioning cooling system would indicate the amount of fluid in the system by the overflow bottle. So unless the system is leaking, putting it in the overflow would get it back into the system just fine.

No cap here, think it goes in the overflow... :)

Start car bring up to operating temp after t stat opens and level drops add coolant then put on a new radiator cap

You want to START filling it while the engine is cool, you need to start the engine and run it to help burp out any excess O2 that’s still trapped in. You can typically squeeze the upper and lower hoses to help.

My radiator cap is behind the vehicles faceplate. I would have to take the face plate completely off EVERY TIME I wanted to check my fluid. HELL NO. I use the overflow to gauge if it needs a top off or not, because its right there on top of the engine.

Funny, it's sez in almost all manuals that IS the way you fill/top off our radiator fluid

I do both unless the car only has a overflow reservoir

My car just stopped! Just replaced my alternator so it's not that or battery 2 weeks ago and it was ok. So I look and no coolant😢 Just brought some coolant and watched your video. Praying it starts

Bro.. you just caused about 1000 second degree burns 🤣🤣

Someone watched this video and went to "add coolant the right way" while his car running

Not on Euro 💶 brands: VW, Skoda, Manseratti, BMW, Merc, Audi, Pugeot, Renault. These cars the reserve is the radiator filling it's dual.

I accidentally did that with my moms pickup truck. I just realized i mixed gold with orange then had to Spend the whole night mixing coolant with half water while using a turkey baster/ extractor and an empty water jug. The Radiator will burn off a little fluid but reservoir should always be at cold fill level. Simply Turn the key to see the temp rise from the bottom of the engine.

Actually, that's not true. Because if the radiator is low it pulls from the overflow due to vacuum

If the engine is cool just keep filling the reservoir! It will fill the radiator

Wrong. It is the overflow and also reserve tank. It takes as the engine needs and also returns when needed

Dam man I feel stupid as hell 😂😂😂I’ve put it in the reservoir for years

There are two types of tanks. -The overflow tank, like the one shown in this video, is just a tank to catch any overflow from the radiator. If you open this tank while the car is hot, it will not erupt. The bottle will usually have a snapping cap and the radiator will have an accessible cap of its own. -The coolant reservoir tank is a direct component of the pressurized cooling system. It will always have 2 or more hoses connected to it and pressure release cap that screws on until it clicks. If the system is hot, removing the cap will cause an eruption. The radiator will not have a cap, as one is not necessary. Know your system. An overflow tank that's low on fluid, means nothing. A reservoir tank that's low, means you might have a problem.

Super helpful!

Holy shit, this was me. Like actually. First time swapping coolant, I drained it, then I put the sealing spout in the overflow, and I was so confused why it was spilling out as I added fluid. It took me like an hour of freaking out to finally figure out that I was being super dumb.

Good to know that, Thanks!

Note that many cars dont have a radiator cap directly on the radiator, they have two plastic containers one taping the radiator and another overflow container.

A lot of modern cars don’t have this. You just fill from the overflow tank and don’t let it run dry. The engine won’t overheat fast enough for it to be a problem and as long as you don’t let the overflow tank go dry, you won’t burn out the water pump. Best way to do it is remove the fuel pump relay, have someone inside the car cranking the engine, while you add coolant to the reservoir, once the reservoir stops emptying out, you’re good to go.

Alone, stuck with two disabled kids, a service dog and zero support help. Your video will get me home hopefully. If not, I lose the car and I'm done, it's over. Here's hoping for the best!

No sir, you are wrong., the coolant is under pressure when hot and vacuume when cool. That bottle displays the coolant amount in system......

Appreciate the video man 🫡

You can definitely add coolant to the reservoir. Even honda manuals suggest topping it up through the reservoir if it’s running low

Well here’s the thing I just filled up my 750li with coolant and it had bleeder valves built into the heads and you can fill the expansion tank because it’s the only access point. Proccess is fill up put car in position two turn on heater to full to turn on secondary pump and bleed that then fill more turn car on then leave cap off for an entire heating cycle after that put cap on run one more heat cycle the next day then go ahead and fill if needed then drive

This kind of advice can lead to people removing the radiator cap while under pressure. Fill the overflow, the system will push out air when hot and pull in coolant when it cools. If your overflow is "boiling" you probably need a new radiator cap.

Yall who beginners please know all cars dont have the radiator cap. So yes put the coolant in the reservoir tank. If you flush the system have prior experience.

That’s an expansion tank a sealed radiator system has a reservoir! Pipe in pipe out expansion tank 1 pipe from top off radiator and a vent to atmosphere

When youve only worked on 1 car ever and dont know what the fk you're talking about.

I was losing coolant but my overflow was full seems my car was leaking, replaced radiator cap, everything works great now

I heard, try to not remove radiator cap from radiator, gasket might lose its ability to seal … You should have an extra cap in vehicle, just in case

If you can’t see the radiator cap you most likely have a coolant reservoir that’s where you add coolant but if you can see the radiator cap always add to the radiator then the overflow to the proper level

It's not overflow, it's just the reservoir putting coolant there will circulate through the radiator

The reservoir is not an overflow, it's an expansion tank. Coolant fills the reservoir when hot and is sucked back in when cools down. The overflow is a hose from that reservoir which dumps the excess of coolant, in case you add too much.

My left ear:🔊 my right ear:🔇

Except some cars you fill thru the overflow like the 97 ford f250 xl

Thank you so much!!

After refilling the radiator, do we put any into the reservoir ?

Most new cars the overflow is the highest point in the system

Im grateful for ALL the comments… seriously 👍

My coolant on the catch tank is below minimium but when I take the radiator cap of, It's full. Is there something I should be worried about?

Is it okay for the overflow to be empty then?

If the clear bottle on the side is low is that good or bad?

Actually it’s correct nomenclature is “Degassing tank”

It’s not an “overflow” reservoir, it’s just a coolant reservoir. The radiator cap had a spring in it that shrinks when hot. Two things can happen in this process if the radiator is too hot or too pressurized. If it’s too hot the spring will open up, and the pressure from the water pump will suck fluid out of the reservoir, or if it’s too pressurized, the spring will open allowing the excess amount of coolant to flow into the reservoir.

Some car (mine for example) need to be filled by the reservoir. The reservoir is higher then the radiator so it fill it until the level line.

Coolant doesn't make your engine colder. It is used to increase the boiling point and lower freezing point of the water in your radiator.

Im good, ill listen to the manufacturer instead

i have an 2019 audi s4 and i only have 37,000 miles in it. i think i put the wrong coolant into the car. should I flush or drain out the old coolant and use like a coolant flush cleaner or just pour the new coolant in. this stuff i confusing any advice?

This was correct until about 10ish years ago, my current car has no cap, only way to fill is that plastic bottle on the side 😂

Yes it is overflow but it is also RESERVE

2013 dodge journey has no radiator cap, it’s only the engine coolant reservoir, am I missing something? Or is that the way my vehicle is made?

Hi, i were to buy a mazda cx 3 but, when i check the coolant reservoir it was over filled, even when remove the cap it got spilled does it normal?

Yep learned that one the hard way blew my head gasket

The overflow bottle for any ford truck is the way you put any freeze into the radiator there's no other way.

i got a check light saying my coolant is low and. i didn't know. I think i might of used the wrong coolant in my car. I went and bought the "Peak Oet Extended life concentrate anti-freeze/ coolant european" I'm not sure if that coolant is the correct one to use in this so please help! i have an audi s4 b9 2019 btw. i’m not sure if this is the right coolant and i’m worried i mixed the oem coolant with the peak oet coolant

90% of cars dont have a cap on the radiator nowadays, you're supposed to put the coolant in the reservoir

You're wrong. The radiator cap for those systems have a check valve. As the system heats, pressure rises. The liquid goes places(tank) as the system cools, it develops a vacuum, overcoming the check valve and drawing in lost fluid from the tank. If you are not recovering fluid from the tank, you have a leak preventing vacuum or your cap is shit.

I be making that mistake all the time. Now I now. Thanks

It can't get to the overflow if the radiator isn't full.. right? McFly...

It's ok to put it in the res if u are aware of how it ebbs and flows based on temp. Obviously if the amount ur adding is substantial then yea u wouldn't but it wouldn't hurt anything unless ubover filled the res and the coolant has no where to go as it heats uo and expands

Do you watch the overflow bottle as you pour the coolant in the radiator cap side to know how much to pour in ? thx

Does a pontiac G6 have a radiator cap?!! WHERE?

You need to explain to the people viewing, some vehicles dont have radiator caps, resvoir caps

MAKE SURE YOU ENGINE IS COLD!!!!!ONLY DO THIS WHEN YOUR ENGINE IS COLD!!!!! kindve odd how he whispered that part though,, if your running around town just fill it in the over flow reservoir tank passed the full line about 1 or 2 centimeters over the full line continue to drive and park again and check again,if the tank liquid has gone down again it has filled the radiator

Coolant overflow reservoir ok . Answer this question . Is it a different circuit ?

Ya right, 1997 Chevrolet cavalier: No radiator cap. I use the white tank, thank you!!!

Works for ones that have a radiator cap. Come across some you have to do it that way.

That works all good unless you have a sealed system, at that point the plastic resivor is your only way to check and fill the cooing system. My truck is a sealed system.