Last Updated on September 29, 2022
While you should check your fluid levels every time you fill-up the gas tank, most people leave it to the mechanics. It’s a huge mistake. Just because you don’t see any fluids on the ground doesn’t mean that everything is working as it should.
There are multiple places your coolant could be ending up, and if you aren’t keeping an eye out for the symptoms, you might end up with an engine that is constantly overheating.
But where is that coolant going, and what can you do about it? Keep reading, and we’ll break it all down for you.
Common Causes of Losing Coolant (But Don’t See a Leak)
Whether you drive a Subaru or a Lexus, your car needs antifreeze. So, when your coolant is disappearing, you need to track down the cause, and you need to do it quickly.
Below are the three most common reasons your coolant reservoir is empty time and time again.
See Also: How to Properly Check Coolant Level
#1 – Head Gasket
It’s likely the first thing a mechanic will tell you the problem is. Head gaskets are notorious for leaking, but it leaks everything right into the combustion chamber instead of the ground. While this won’t leave any visible signs on the ground, it will be pretty straightforward if you take a quick look at the exhaust.
If you have a blown head gasket, you’ll have a ton of white smoke coming from the exhaust. This is because unlike gas, which leaves mostly clear or black exhaust fumes, coolant burns white, no matter what color of coolant your car uses.
Expect your temperature gauge to rise way past normal also.
#2 – Radiator Cap
If you’ve ruled out an internal leak, that means your engine is burning the coolant somewhere else. The most common place is the radiator cap. Radiator caps hold the pressure inside the system, but if it’s not sealing properly, then some hyper pressurized coolant will escape in the form of steam.
Once your engine is warmed up, you’ll be able to tell if steam is escaping from your radiator cap by merely taking a quick look at it. You shouldn’t see any steam or smoke coming from the cap, and if you do, then you’ll need to replace it.
See Also: Can You Put Water in a Radiator in an Emergency? (It Depends on the Type)
#3 – Leak Onto the Engine Block
While a leak onto the engine block will typically leave a puddle under your vehicle at some point, if it’s leaking directly onto the top of your engine and puddling up until the engine warms up, it might burn the coolant off before it can reach the ground.
While it’s rare, it can happen, and just like a bad radiator cap, a tell-tale sign is a cloud of white smoke coming from the engine bay while the engine is running.
Step-By-Step Troubleshooting Guide
When it comes to disappearing coolant, finding the culprit is often the easy part. If you follow our step-by-step guide below, you should be able to identify the problem without ever needing to take it to a shop!
#1 – Check the Exhaust
It’s the most common reason that coolant burns off. It’s also one of the most straightforward problems to spot. All you need to do is look at the exhaust smoke while the engine is running. If there is excessive white smoke, then you have a blown head gasket.
However, just because there is some white smoke doesn’t mean that it’s a head gasket. It needs to be an excessive amount.
During colder weather, your vehicle will have more smoke coming out of the exhaust then during the warmer months. This is entirely normal.
#2 – Check the Oil
If you’ve looked at the exhaust smoke and still can’t tell if you have a blown head gasket or not, then take a look at the oil. Simply pull the dipstick and see if the oil level is rising over time.
When you get coolant in the combustion chamber, it doesn’t always get completely burned off. If it’s left in there, it’s only a matter of time before it works past the O-rings and finds its way into the oil pan.
If you’re an experienced mechanic, you can tell by merely smelling and feeling the oil, but novices often have to keep an eye on the level to see if it’s rising.
If you do have coolant in your oil, you likely have a blown head gasket, and you need to have a mechanic take a look at your engine.
#3 – Check for Engine Smoke
If your engine is smoking, that’s a sign of a problem. Try and track down the smoke, but if it’s white, then it’s coolant.
If you don’t have a visible leak underneath your engine, then you should take a look at your radiator cap or anywhere along the top or sides of your engine. If you find any antifreeze, then you’ve located your problem!
Thank you very much for your very good article
Perhaps the reason for water loss could be a leaking welch plug.
Yes, this is definitely possible. I actually had to look this term up because I know a welch plug as a “freeze plug”. Both names refer to the same part.
thanks u very much,this was helpful
Just checked radiator cap and hose no leak cap is on properly, put coolint in 2 days later all gone can’t seem to find the problem
Help
Try performing a leak down test. You may be losing coolant internally, through a head gasket leak for instance.
Sometimes coolant leaks are hard to find. They make dye you can put in your coolant that shows up under UV light to make detecting leaks easier.
How does a radiator thats installed wrong affect a 2006 Chrysler PT Cruiser
What was wrong about the installation?
Any ideas plz I have had problem with overheating for a while now and can’t find why. Have had head skimmed gasket replaced water pump timing belt thermostat housing replaced new rad cap within last month n went on 40 mile journey n lost all water gone on small runs n no problems never had so much trouble or work done on a car as this one don’t no what to do next
Can you tell if the coolant is leaking internally or externally? When you say you had the head skimmed, do you mean it was decked as part of a head gasket replacement?
What is the year, make, and model?
I have a 2007 Jeep Commando had the water pump done new radiator new thermostat in my cooling system still be running out and don’t see kno leak underneath
Is the vehicle overheating? You could try doing a leak down test to see if you’re losing coolant through the head gaskets or something like that.
Pressure test radiator for leaks, if no leaks present, use a leak down test kit don’t forget that the engine BLOCK could also be the culprit, not just the cylinder head/gasket.
Yes, that is a good idea.
I have a Jeep Wrangler 4.0. It apparently has a very small coolant leak. I can smell it but cannot find it even with a pressure tester. The coolant level stays the same. With the engine off the smell is strongest around the radiator. No visible leaks. Any ideas? Should I try the UV leak detector fluid?
UV leak detector might not be a bad idea. Did you check the coolant level in the radiator and the overflow reservoir?
If you smell coolant and the level doesn’t change, perhaps you had a leak in the past and you’re smelling the leftover spill? You might be able to see some white streaks coming off of some of the cooling components. This may indicate the presence of a current or past leak in that area.
my 08 scenic 1.5 dci is losing coolant but heaters work no white smoke no lack of power had coolant pressure rest done and no drop in pressure what can it be
You could try doing a leak down test to see if you are losing coolant out of the combustion chamber.
It is also possible you could be losing coolant but it evaporates before it hits the ground. Look for white streaks in the engine bay, particularly around coolant hose clamps. Do you smell coolant in the engine bay anywhere?
They make a special UV dye you can put into the coolant and that may help you track down leaks as well. After adding the dye, you can use a black light to see where the coolant is going if it’s leaking out of the engine.
I have kia sportage km 2009 after 2x General overhaul but still consume all the coolant in 3 days for 2 years straight. I change thermostat,radiator, reservoir tank, radiator cap,coolant hose but still the same, checking for leak and no any visible leak or anything. Hope you can give some suggestion
I would do a radiator pressure test to see if I could spot a leak while the system is pressurized. You may notice coolant leaking onto the ground when you do this. Sometimes leaks only show themselves when the system is under pressure.
Same problem with my Kia sportage 2008..
Losing coolant but the mechanic cant see any leak..
Did change radiator as well?
bad overhaul crooked cylinder head maybe cracked block
Hi I have 2004 vy Ute and suddenly water is leaking ? To don’t know. There’s no smoke. No milky oil either . , it just started happening yday morning . And heater don’t go. Could thermostat make this happen? . There’s no leaks on ground either thx jon
Can you tell where the water is leaking from? Are you just slowly losing water level in the overflow reservoir?
Hi I have a 2006 Dodge Grand Caravan and it is slowly losing water from top of motor where head meets exhaust. The oil is not milky, is this a head gasket problem?
Sounds like it might be. I’d get it checked out.
My hi I have 2012 dodge grand caravan I replaced cooling system on top of motor water pump thermostat radiator cup and still overheating up to3/4 of the gauge and losing cooling fluid smell burn help
I would consider doing a leak down test to check for head gasket failure. During the test if you see bubbles come out of your radiator, that’s not a good sign.
Hey, did you find out what was the problem? I have a 2014 dodge grand caravan and I have been having overheating issues since I got the van. We will fix something and then a few months later the whole problem will start again. It’s upsurde to me…
Hello,
Can anyone please help. All mechanics are booked and can’t take my car.
I have a BMW ( yeah i know, I know) and I just filled coolant and oil full and after a 3 miles drive I went to check and bone dry, there is no leak I can find , no puddles, exhaust is transparent, no white smoke or and underneath hood is all clean. But when I open the oil resovior it does have a little burnt smell. I don’t understand because I took it for oil change and they said nothing. I took it to mechanic last month and he gave me paperwork that said he couldn’t find a single problem wrong.
Please help. I am a female and I feel like I’m getting a run around because I have no clue about mechanic of cars
Are you saying the radiator and the dipstick were both bone dry after filling them with their respective fluids? Are there any warning lights on the dash?
Hey, so I’ve got a ’92 Lexus LS400 that seems to have a coolant. I’ll refill the reservoir and after about a week it’ll be either very low or gone. Heater blows hot after I refill but after that week it only works well after you rev the engine to 2k RPM. Then it’ll only work during freeway driving. Engine does take a while to warm up from startup, but doesn’t run cold or hot. Right in the middle once its warm. No visible leaks, no headgasket leak, no white smoke, no smoke from engine bay, thermostat is not stuck open. Could maybe air in the coolant system cause this? I mean I always bleed it so I have no clue. Any help is appreciated!
Sounds like you do have a leak somewhere. You could be leaking from the intake manifold or a head gasket even without visible white smoke. You could try a leak detection kit if you want. That kit looks for exhaust gases in the cooling system. It’s pretty cheap and easy.
It’s possible you’re losing coolant from somewhere in the engine bay and it’s just boiling off before you notice it on the ground. Are there any white streaks in the engine bay? Coolant that evaporates tends to leave white streaks behind.
If all else fails you could do a leak down test to see if you’re losing compression to the cooling system.
Please i have a Toyota Corolla my coolant overflow always I drive for 30min out of the tank I have changed tank cover but still come out to the reserve tank and overflow
Hello. We have a 2005 Jeep Liberty diesel. We keep losing coolant. This has been going on for a couple months, but the mechanic said everything looks okay. It did overheat for a while, but now that we know to keep adding coolant, it’s not overheating. We had a little white smoke this morning. We are not in the US (in Croatia at the moment), and it’s difficult to get a mechanic to take a look at a Jeep. We added head gasket sealant this morning, but the coolant is still disappearing. Does the sealant need time to cool down? Should we return back to Albania and have our mechanic change the head gasket?
Try to figure out where you’re losing coolant from. It could be as simple as a leak in the overflow reservoir, or the hose that connects the reservoir to the radiator. Perhaps the radiator cap and filler neck aren’t sealing well. If you notice white streaks anywhere in the engine bay, I would start there. Once coolant dries, it often leaves white streaks behind.
Excellent advice and tips on coolant leaks! I have a 2004 Acura MDX and had the radiator replaced with new hoses and thermostat because they were old and original and radiator started leaking. Two months later, I noticed the temp gauge started rising and engine overheating so I had to pull over. I ended up adding almost half a gallon of the blue Asian coolant. So far so good, no more overheating signs. My questions, would using wrong coolant cause a drop in level and overheat or is it common for coolant to drop in level because its a new radiator? Thanks for your help in advance.
The coolant level probably dropped as the cooling system was bled of air over time. After replacing the coolant, you have to bleed the rest of the air out of the system or you risk overheating.
It’s also possible that one of the radiator hose clamps (or other coolant hose clamps) aren’t tight and you’re slowly losing coolant that way.
Hello – I have a 2004 Acura MDX with about 140k miles. The car drives fine but on a few occasions white smoke have come out of the engine area, but when it happens, it’s only happened after driving uphill for a a few miles. The temperature gauge never springs pass the mid range.
I’ve noticed a drop in coolant level and I’ve refilled it once in the past 10 months. I’ve taken this car to the mechanic a few times, and they diagnose that there are no leaks (visual and pressurized tests), no milky oil, no blown gasket…they just tell me everything is fine.
Any ideas what the white smoke is about?
If your coolant level is dropping and you see steam, there is a very good chance that you do have a leak that was missed in their test. Maybe it’s an intermittent problem.
Does the temp gauge ever creep above the exact center of the gauge? Some temperature gauges aren’t very accurate and you can be running hot even when the needle isn’t pegged at the hot side.
How quickly are you losing coolant, and how often do you need to fill it up?
My radiator coolant mix with engine oil but no physical leakage and the coolant always reduces whenever I drive the car toyota Corolla 2006 model
Could be an internal head gasket leak. Do you notice any white smoke from the exhaust?
2003 Pathfinder w 125k. Im the only owner. car taken very good care of. So, a week ago, i happen to notice i had no coolant in receptacle. Filled to max line and 5 days later, no coolant. No leak on ground, no stuff on cap, seal is good, no white smoke from exhaust and my car IS NOT OVERHEATING…..I just dont understand…..
It’s possible that you have a leak somewhere that only manifests when the cooling system is under pressure. I’ve seen leaks before that won’t leak a drop on the ground until the car is hot. You can often find these by doing a radiator pressure test. You connect a pressure gauge to the radiator filler neck, pressurize the system to the amount the system is supposed to hold (often around 1 bar), then check for leaks in the engine bay and on the ground.
Barring that, you could try a leak down test to see if you are actually losing any coolant into the combustion chamber. I would try the radiator pressure test first though.
Couldnt edit comment. Sorry for 2nd post, but also when i open radiator cap,I can see the fluid right there. Didnt know if that was normal.
You are supposed to see coolant when you remove the radiator cap. If you did not see coolant, that would indicate your coolant level is low and there could be air in the system.
2012 Chevy Tahoe I have to put water in it every time I move my car it doesn’t run hot r anything and I don’t no where the water is going
You could try doing a radiator pressure test. Sometimes you only loose coolant when the system is pressurized. You might not notice this type of leak in your driveway.
If you are losing coolant over a longer period, two to three day’s, but it has gone, vanished.
This happened to me. Check your radiator hoses for a fine vapour spray around the connections, there will be no visable sign of a leak because the coolant has evaporated into steam leaving no trace.
The only reason I found the leak was because I had opened the bonnet after a small trip, as luck would have it, I heard the fine hissing, very fine hissing where the top hose connects to the engine, the problem wasn’t the hose, it was the housing the hose fit onto that had corroded enough to create a bad fit for the radiator hose.
I replaced the housing and hose.
I should add that the fine stream of vapour came from the top of the hose so was visable when I opened the bonnet, if It had been off to the side or on the bottom I would never have seen it.
If you can’t see it but you can hear it, don’t be tempted to run your had’s around the hose to feel for any moisture, it is steam we are talking about here. Burn-es.
I have a 2000 Daewoo Matiz 0.8cc. After reading some of the comment’s I thought I would chime in with my experience with losing coolant.
My problem started with the temperture gauge getting a little too high, I popped open the bonnet after returning home, this I feel is the important part, I opened the bonnet as soon as I pulled up the driveway, there was the smallest hiss of steam coming from the thermostat housing and the radiator top hose, if I had checked under the bonnett 10 to 15 minute’s later I doubt I would have noticed the hiss of steam. Soulution… Replace thermostat housing, thermostat and top hose, the housing had corroded enough to break the seal between the hose and housing.
Thanks for the tip, that’s useful info.
Ok so I loss about a cup in a
Month. No leaks, no white smoke under hood and as far as I can tell none out of the back pipe. This has been happening for a year now. Took it to get checked and came up with nothing.
Yeah, you shouldn’t be losing coolant. Sometimes coolant evaporates with little to no trace. Sometimes you’ll see white streaks near the source of the leak. They make a special dye you can put into the coolant to help you trace leaks.
Check all hose clamps and fittings to make sure they are tight. Look around the radiator filler neck to make sure you don’t see any white streaks. Check the bottom of the radiator as well.
I have a Chevy avalanche 04, I keep adding coolant but it’s disappearing, and I see no leaks. Help?
How often are you adding coolant, and how much do you need to add? It’s hard to give more specific help besides what is already in the article, given that information.
I really could use some help. Our 2017 Ram 2500 coolant is disappearing fast. No visible leaks on the ground, no coolant in the oil (this was confirmed by two different mechanics) oil was changed, water and no additional fluid. NO unusual exhaust and NO steam/clouds coming from anywhere in the engine. It’s not the headgasket. The engine is not overheating at all it’s maintaining a temp of 192.2 F. We have driven the truck from Florida to California adding several gallons of coolant. No issues other than having to pull over every few hours and add coolant.
We have ruled out every item on this list… are there any other causes you didn’t mention? This is crazy. Thank you for your help
Sometimes coolant only disappears when the system is pressurized. You can try doing a radiator pressure test to see if you lose any coolant while the system is under pressure.
I have an undetectable leak in a 2017 Ford Expedition. I think it is a very slow leak as there is no puddles or drips (I removed all the under engine covers) until the coolant level gets too low and the pressure valve pops. The engine temp still looks normal but the coolant level is low. Once I refill the coolant, no more leaking and all runs normally. This took about 1 year to manifest itself.
Question: If I use the UV leak test fluid, if the coolant is leaking into the cylinders due to a bad head gasket, will the UV show up at the exhaust? If I hold a black light at the end of the exhaust pipe, will it still show after being burned off??
That’s a good question, and I’m not sure about that. I would not expect the UV dye to show up in the exhaust, even if you were losing coolant this way. Combustion may change the properties of the dye, and the carbon from the engine could also cover it up.