How VW Coolant Bottles Fail

[@EL-Duder-Reno]

My coolant bottle just broke and I knew I could count on the humble mechanic for the right info. Thanks

[@jgrant1162]

Hi, might be worthwhile updating this video. Many newer vw/audi/skoda/seat, have a marking on the bottle ' Mit Silicat', german for with silica. This means it contains a small pouch of silica, in the bottle. these pouches have been known to fail, and clog up the cooling system, especially badly affected is the heater matrix. To avoid this, I removed the pouch, flushed the system and filled it with the correct mix of vw evo 12 coolant, to ensure the coolant retains the correct anti corrosive propertie.Keep the videos coming, I find them really helpful!

[@MrGary10k]

Thanks My friend. My 2013 Tiguan had this happen today omw home today. Watched the temp like a hawk when I pulled over. Temp read like it always does. Letting the motor get cold. Now I know what to look for. Thank you much!

[@alansauer6853]

My 04 Jetta was running hotter than normal. I had already changed the reservoir and cap. I then changed both the thermostat and ects ( engine coolant temperature sensor). Well everything is perfect again. I don't know which part was the problem, but since I had to drain the system I thought I just change both parts . Thermostat was$9 ,sensor was$17

[@andreturner4190]

yes I also have a 2004 Jetta 1.8T engine the reservoir cracked at the top and I just ordered another one not only did that go to coolant control temperature when also I replaced that but now it doesn't seem to be working I guess the whole problem is the coolant reservoir bottle

[@prettybaby80]

I had the whole bottle replaced last month. Warning light went away. Two weeks later it’s back on . Sick of this beetle honestly

[@BryanKnight877]

very cool, I'm pretty sure I have this exact problem on my 2006 Jetta TDI, the low coolant light comes on when the engine is cold, but if I turn the car off and back on again after it warms up slightly, the light doesnt come on, and the coolant reservoir is full

[@pwollerman]

Same here - did cleaning the electrodes fix it? (OK - 6 years ago but hopeful : )

[@drivewasher]

Just thought I'd mention this, as I had an issue with coolant level sensor on a Skoda (same as VW & Audi). The 2 prongs in the bottle dont relay resistance the cluster module calculates capacitance. This type of sensor is called a capacitive sensor.Similar arrangement also used in the sump pan to detect oil level, but the capacitance calculator is built into the oil sensor.

[@bonifatiusshimbaranda]

Correctly said...

[@mercer982]

all old mk3's have the bottle so fuzzy you can't really tell how much coolant is in there.

[@Chris-zg8rk]

I Have 215,000+ miles on my 2004 Jetta TDI, got the coolant light and ended up being a leak at the small hose. Speaking from experience...TAKE YOUR TIME CHANGING THIS RESERVOIR- The parts of the reservoir that connect hoses/connector were VERY brittle. The old reservoir doesn't matter but the job is way harder and longer if they break on the inside of hose or even the connector clamp. Cheers and good luck!

[@themachine8009]

I’m replacing mine today. Very excited

[@StevenPatrick]

hahah u rock dude i been workin through this problem for the last week ... I even parked the vehicle thinking it might over heat and was getting ready to go buy a new thermostat , heat sensor and water pump just to say hey these are all new ........ and i should probably do that anway but thats another day so the first time i checked the level in the coolant bottle the car was running and it looked fine ........i just went out and checked it while it was cold and not running and wa la sure enough it was low so i filled it and started it up and bingo no more red light ........ sometimes its the little things in life that make you feel so stupid lol but thanks for the video you saved me money for the time being yet i will replace all the cooling components soon ......... u saved me time and money for now and released some of my stress hahaha

[@RahulSharma-lw3ei]

HumbleMechanic , I have a trouble with my vw Polo 1.2 MPI (Petrol) here in India. Recently, i am observing some weird engine RPM while driving. My observations are as follows: 1) At cold start Engine RPM is 1300. Then, it falls down to normal 900 range after a slight warming up. 2) When the vehicle moves, in the 2nd gear with an RPM close to 2000, and if i leave my foot off the gas paddle, the RPM hesitates to fall down immediately. Basically, it stays at its place and starts to fall after say 1.5 seconds. Same goes with all the gears after that. 3) RPM up : Gas Paddle Off : RPM needle does not start falling, but stays for a sec and then begins its fall. 4) Later, when the engine is up and running for a while and if i stop at a traffic light, in neutral, the RPM stays at 1200 and does not come down to normal idle(say 900). 5) If, i press and release the gas paddle once or twice...then, somehow sometimes, it returns to 900. . P.S. I took the car to VW show room and they said car is normal after driving. But these fluctuations are definitely not normal. I tried to correct it by myself, i cleaned and checked the air intake filter(it was clean) Opened up the throttle body pipe, and cleaned up a little carbon deposited around it(with engine off and gas paddle pressed with key on). Still the problem stays. However, cleaning throttle body intake, made the gas paddle responsive. Initially with the press of paddle i was not getting an immediate RPM up too. This issue is fine now. Please help if u can. Pardon me for such a long query . Thank You.

[@robertgreenfield9051]

Replaced one today that was so corroded it didn't even register continuity

[@richard66754]

This would be a great video to launch off into VW coolant system woes. I had a coolant light and a p2181 error on my daughter's 2003 Beetle. I replaced the reservoir and still had the coolant error.😬 it ended up that the thermostat was stuck open and the engine wasn't getting up to optimum operating temperature. The water pump wasn't suspect because we had already replaced that due to a broken plastic impeller and previous coolant error. All said and done, we still love our driveway full of VW cars!

[@monkkeylover123]

best video yet on this subject. I have 2001 Jetta. Have flushed and filled with VW coolant. Always the one sensor rod closest to firewall corrodes. have replaced 2 times. No coolant migration. Even after flush/fill, coolant gets brownish. Could this be oil and could it be due to a bad oil cooler or seal? Thanks

[@omnizen]

My mechanics worked on my 2003 VW Passat 2.8L GTX cooling system to find and repair a leak. A couple years later the heater core was replaced after removing the dash. I am fairly confident the coolant system was completely flushed both times. But after the first repair, the coolant bottle swelled up and developed a crack on top. The coolant bottle was replaced. After replacing the heater core, the coolant bottle again swelled up and developed a crack on the underside. Sometimes when I stop the car, steam comes out from under the hood from the coolant dropping on the hot engine. I have to top the coolant frequently. After the second repair, I replaced the coolant temperature sensor myself but did not burp the system. Now I know better. But do you think the swelling and cracking coolant bottle could be from air in the coolant? The gauge on the dash indicates the car is not overheating, and there is no problem with the heater core for cabin air. Any suggestions are welcome. - - Also, could you discuss how the VW Passat coolant bottle cap functions. I have come to the conclusion that the cap opens and accepts air into the bottle after the coolant in the radiator cools down and creates a vacuum in the coolant bottle. Looking through the cap opening, there is a small side compartment with a drain tube down the backside of the bottle open to the ambient air pressure. Somehow the air must get into the center cup in the cap after the plug is sucked down, but I do not see any openings or even pin holes. I cannot find anyone on KZbin or Google describing the function of the VW coolant bottle cap.

[@marcusag2733]

Hey Charles. I have a 2004 vw touran 1.9tdi 102hp. After a new head gasket, water pump, timing belt and a lot of other small stuff, I have a problem with my coolant. After 15min of highway driving I get a low coolant warning. And when I check the coolant tank is empty. Unscrew the lid and all of the coolant comes back. What do I do?

[@dannywooding4009]

Having the same problem with my 04 Volkswagen caddy

[@mykkeau]

My 1985 mk2 doesn't have any lights for warning me about low coolant levels and such (It has 4 lights total, power connected / warning light for engine running too hot / oil low / high beam), I just check all its fluids monthly, works for me.

[@twocups8994]

Hey Charles I know this is kind of an old video , My coolant bottle has changed color to a dark brownish kind of orange color I'm not getting any lights on the dash but do you know if I would have to replace it?

[@abepenner4714]

Did you solve this? My car has the same thing

[@kilovwdude6457]

It’s fine but the discoloration means the plastic is being Eatin into id replace it if you are worried about it

[@NBDFJOB]

Surprised you didn’t mention more about the caps failing. I’ve had 2 VR6 Corrado’s both with overheating problems caused by faulty caps.

[@HumbleMechanic]

I have seen 1 cap fail in almost 15 years. It's possible for sure, but not super common from what I have seen

[@NBDFJOB]

HumbleMechanic it’s possible it was just a problem for the European market. Either that or I’m just unlucky!

[@xncx123]

my coolant cap shot off leaving the threads still threaded what would cause that much pressure to make it explode like that

[@OhWhatFun]

On to my 3nd cap. And 2nd bottle!

[@Peace_and_Love_777.....]

Agreed... it is a faulty seal in the caps

[@charleshines5700]

I had a couple Volksagens that used a round one just like that. There must be minor differences like the cap and bolt hole locations. Over the years the cap is one change that is easy to see since the color and style changes but they all look interchangeable otherwise but probably are not.

[@amcrae1]

Can you tell me what the voltage is supposed to be at the coolant bottle? and THANKS for the video!

[@aaroneverett296]

I need to stop watching your videos. Everytime I see one I think I need replace something. So far I'm replacing the valve cover, vacuum pump, and map sensor. Luckily haven't seen any sign of this failing.

[@HumbleMechanic]

Lol don’t stop!

[@tusharin1984]

Dude, great video. Yesterday my wife, son and I were getting ready to run around. Backed my car out of the garage (2012 Passat SE V6 B7/NMS platform) and the light started blinking. The coolant is below the min in my resovoir so I headed to autozone today to pick up some pentosin pentefrost e. Manual says that light is a coolant system malfunction. I’m surprised there wasn’t a a low coolant warning light that came on, however my wife drives it daily and hopefully she didn’t over look the warning light. Being that the light flashed however based on your video I will look at the contacts and see if they are gunked up. There is approx 70k miles on the car.

[@darinhill6543]

So upon further discovery: when i went to add coolant to top off the reservoir, the first thing i noticed was that the cap was loose. This was probably done during the last service at the dealer. I'm assuming i lost coolant due to evaporation?? I guessed accurately at adding 16 ounces of fluid (8-oz coolant, 8-oz distilled water). My next question is since the system is to be pressurized, would there be contingent damage due to the cap being loose? Any thoughts ?!?!

[@johnbranca611]

I have 2004 jetta tdi that I just got a few months back. Did a complete fluid change of all fluids. Noticed inside the reservoir that one of the electrodes inside was completely missing.... The red light would randomly come on telling me my fluid was low.. Which it wasn't, but since one of the electrodes was missing, figured I should replace the bottle. Installed new one, and all was ok for a little while, then it started again with the light. Checked bottle, the same electrode on the new reservoir was starting to gunk up and, I had some coolant migration into the connector.. Not heavy, but would classify as moisture. I cleaned the electrode with a tooth brush. And it's fine for a bit then gets gunked up again. I just received the replacement reservoir from ECS tuning, free of charge, and I'm hesitant to replace it. For the time being, i have the plug disconnected and jumpered. Something, has to be causing the coolant to flow up the electrodes and into the plug?. The one electrode is acting like a sacrificial anode. I can replace bottles and engine harnesses all day long.... until the root cause is addressed, I'm afraid this will continue... Your thoughts?

[@BenjamenMeyer]

Working on a 2005 Jetta GLS with a 2.0 and replacing the coolant bottle after it started breaking down and leaving chunks in the reservoir. Found it while doing a flush with water.

[@KittyCakeHate]

Thank you, very detailed information. I am about to check it and I am praying it's not the connectors.

[@BeeShopcs]

For my Audi the square one I have changed it 2 years before. Issue was the return side broken. But it's good 11 years life in area which 50+ cc 3 hot seasons.

[@dj_marty_d]

You keep saving me money!! Very straight forward. Thanks!

[@danyo1972]

Cap failed on mine years ago. Spilled the coolant out every time air con was on. Can be serious if a very hot engine suddenly loses a bunch of coolant through depressurising quickly. If it happens to you don’t drive it, let the engine cool down. If you need to get home, top up up with water to get you there, get a replacement cap asap.

[@nunodaniel9458]

Mine is throwing coolant out too .. Does cold starts even after drive it for some time, temp gauge does not work properly.. engine seems to be running fine, no power loss at all but just can figure it out..

[@bubblebubblegum2732]

Yes. Mines keep leaping out.. I fill it then it is gone 2 days later... and my overheat light keeps flashing when it's hot

[@maxvorobey1316]

So I had my ac on high blast in my vw golf 2013 and it was a really hot day. After about 15 minutes, the coolant light came on, and the engine temp started going up. When I looked at it I found spilled coolant on my headlight, and around the coolant bottle, along with some spilled below it. There was also a puddle right below it on the ground. Was this just the coolant bottle spilling coolant from the pressure? Or is it something worse like a pipe or a plastic flange? Thanks!

[@brianvazquez6854]

Max Vorobey same question did you ever figure it what it was?

[@scottlinder2258]

Thanks for the video! Saved me some dough and a trip to the dealer for something in my wheelhouse!

[@V10PDTDI]

We don't replace them too often last week I replaced one on a 2003 Passat 1.8t the return nipple was broken. One thing to check when you screw back the cap on is to make sure that the O ring is there or in the right groove.

[@saeedsuleman3252]

Thank you so much same issue on my jeeta tdi mk6 i done timing belt already but after 20km happen to me and every time between driving temperature light is on and after gone few minute later i check my car everything look normal no over heating coolant level perfect only issue coolant bottle bad 🙂🙏

[@sollykhan2385]

Thanks for this really 'COOL' video Henry,as ever great content man, keep on posting these 'COOL' uploads 🙂

[@michelelara5982]

VW service wanted to charge $199 to replace the coolant reservoir…. Idiots! This part costs $25 and it takes 15 minutes to replace. I’m following you for more videos! Thanks.

[@willrobinson1671]

Thank you very much HumbleMechanic. Very clear explanation, very informative.

[@Alfra1324]

My just went out at 74000 miles! 2012 VW GTI!!! It took me 15 min to replace, easy job!!!!

[@redbeard9760]

Thanks for the great info. Replaced my coolant bottle on my 2007 Jetta 2.5L this morning, and now I have a leak on the driver's side of the motor, leaking on the top of the trans... I was just curious if you may have a link to a diagram of the cooling system, and maybe an idea of what to check. Keep up the great videos!

[@ultrafloss492]

Tim Dodson I hope you've got it already fixed but if not, it might be the coolant flange. Do check with a mirror as well at the bottom part of it because if the leak is minimal it won't be easy to spot.

[@redbeard9760]

ultrafloss492 I just saw this comment, thanks for the advice. I have that part of it fixed, it was a cracked hose, but of course, now the water pump is out... Trying to find a fair price to have that replaced. Just glad we had something else for the wife to drive for now

[@ultrafloss492]

Tim Dodson good luck! I hope you'll get it sorted quick. :)

[@stevenrhee4940]

Ultrafloss which hose was it ?

[@Othermind972]

In 4y i replaced two times the coolant bottle. Very bad quality.

[@carlostettey2889]

I'm using a Skoda Octavia and I saw smoke coming through the air conditioner vents... the coolant tank was empty... i refilled and it happened again after few kilometers... no leakage under the car. I will check the cap

[@michaelsullivan8934]

Thanks for all the videos! I have a 2008 mkv GTI, fsi engine. I just developed a bad coolant leak a couple of days ago and it seems to be coming from the lower front area of the engine. Where should I start looking?

[@TommyCubed]

Its probably the radiator. I had something similar on mine and it was a busted radiator.

[@djansen2442]

This video is awesome. You just saved me like $200 worth of gravy work at the shop.

[@PanamaSticks]

So does the coolant evaporate, or does the low level indicate a leak, or worse, coolant getting into the engine?

[@danyo1972]

Doesn’t evaporate, closed system. So if coolant level drops you have a leak, and hopefully it leaks externally otherwise you are in trouble.

[@LynxStarAuto]

Lol I just replaced one on a MK7 Jetta with 7k miles. 🥴 the newer ones tend to see the cap fail. The cap doesn't vent apparently, and the system over pressurized causing the cap to press upwards and gum up the threads. Then you can't remove the cap without destroying the bottle threads 🤷‍♂️

[@splah01]

Surprisingly you didn't mention the bag of silica that is inside them, at least on the euro models. They can burst, sending the stuff into the engine cooling system. Gave me a breakdown for overheating, took out the heater matrix and 12 months later looks to have been the cause of a catastrophic water pump failure. Have 47k on a b8 Passat, luckily all sorted under warranty.

[@HumbleMechanic]

That started after this video came out

[@splah01]

@@HumbleMechanic well that would explain that then 👍 I understand it's not that common a problem, but I also think a redesign would fix it. Mine is a 16 BTW.

[@The_Enforcer14]

in Argentina several volkswagen do not bring the sensor ... hopefully they bring 4 wheels, engine and chassis

[@annomyous1]

02 vw gti vr6 with over 400k and still going. 09 gti as well. Not to mention the rest of the fleet from big rig to diesel 3500 and 2500 and f250 and motorcycle. Out all them vw is the biggest pain between the secondary air injection tube coolant globe the climate controls and radio ignition switch harness cooling fans

[@nelon5234]

Do you think that a crack-leak in the bottle would also cause the engine to idle higher? 2010 MK6 Golf TDI far from stock. My drives are short so I think the battery is just not getting charged, but it is a VW!?

[@wesleyhurd3574]

I'm wondering if the electronics monitor the coolant level circuit for a low resistance (high conductivity) condition. In other industries, conductivity is used as a measure of the impurities in water. High conductivity would indicate a high level of impurities (or a short in the monitoring circuit).

[@Nikolias007]

I have a 2003 beetle 2.0 and I replaced the coolant bottle and ECT with after market parts and they don't seem to be functioning correctly is this because they are cheap after market parts or a deeper issue?

[@Brainiarc7]

I’ve had a similar issue with a Touareg. Replacement coolant reservoir tanks kept exploding.

[@daemn42]

I had the plastic crack around the coolant return, replaced the bottle, and now I'm losing coolant at a furious rate, but don't know from where. It seems to be collecting on the rim around the middle rim of the bottle, but have never managed to catch it actually coming out of anywhere. It's gotta be the cap or the overflow tube, or the sensor port.. but that narrows it down not at all. I tried a new cap and it doesn't *feel* like it is as snug as the original one, and leaking just as bad (if not worse). It's like the tolerances of the new bottle opening just don't match the old or new cap.

[@gregorythoman8281]

Replaced my coolant bottle in my Audi A4. It was fine but looked a little rough. I installed the new one. Then it got very cold and I needed to move it out of the way and the damn thing broke because it was cold. Of course I had thrown away the old perfectly good one. Here is a hint: don't screw with any plastic part when it is -10.

[@Venenooffroad]

Thanks for the video, do you have a video flushing coolant through de vent line of the coolant reservoir? for audi Q7, Touareg, Porsche?

[@charleshines5700]

That thing with the wires being covered with coolant. I would assume that changing the coolant on time could help prevent that? It does turn acidic with age. Please don't think of it as just water. It is more like highly toxic water that is a mix of different chemicals. Also I imagine that some water pumps could be saved if it is changed on time since the coolant also lubricates better than water does on its own.

[@31biga]

Still a problem on MK7 Jetta, coolant made it's way from the bottle to the BCM through the electrical harness. 2019 Jetta, 18 000 km. Now parked at the dealer because the BCM is back order and the car is f****up

[@AdrianMartinez84]

Hey Charles, How difficult is to do a coolant flush? Need to do one on a 2012 Beetle Turbo. Thanks for all that you do!

[@HumbleMechanic]

+Adrian Martinez not too hard. Many times a drain and fill will do the trick on a car that new :)

[@diegojaimes8008]

Theres a plug at the bottom of the radiator which allows for easy emptying

[@joshuashaw9331]

my mk1 TT coolant bottle exploded and wrecked my bonnet!

[@emiliomartinez3201]

I have a Gti 2.0l turbo and have a problem with coolant circulating, what do you think I can check?

[@snoopy5736]

Did u ever figure it out?

[@bryanyasuhara2994]

Doing mine tomorrow. Thank you!

[@DJDrue]

very helpful video, answers a bunch of questions I had. Thanks so much for posting.

[@morenalephoto5492]

Hi watching this video in 2024 from South africa I'm working on a golf7 gti the temperature goes up to 130 when pressing down on the gas and a warning saying coolant level sensor range performance

[@morenalephoto5492]

Please assist

[@pg6803]

Coolant Fault every next day level went lower so what should I do ?

[@srianthanaidoo3665]

I have a golf 7 gti that had a small front damage. we replaced the radiators and everything with geniue parts- all new parts. we bled the system but the coolant bottle is bubbling like water in a kettle.

[@danny192]

Any update on your car? Mine is doing the same thing. Thanks!

[@vrtxs1938]

This is driving me crazy 😤 idk If my reservoir is bad or the pipes are bad everything is soaked with coolant and the leak is so bad I fill it up 3 times a day

[@clint1285]

Me too.....sick of this leak....

[@TylerPKegger]

My temp light came on and the liquid inside my coolant bottle was boiling like water on a stove, any ideas what could be causing that issue?

[@alansauer6853]

Hi. I watch all of your videos. I don't know if you answer questions, but I have a question about my 2004 2.0litre Jetta. It just started to run a little hotter than normal. The temperature always ran with the gauge straight up in the middle. Now its more like 1 o'clock. I changed the reservoir and cap because there was small leakage around the return line. I also bought a thermostat and a coolant temperature sensor. What does the sensor do? Does it control hi and low fan speed?. I'm not sure how the cooling system works. Thanks

[@martyray518]

I just changed my coolant , fresh and clean . It’s still running hot 200 to 230 . Normally it would run at 190 always . What do you think ? Water pump ?

[@802Garage]

If you have time, I have a question. If I'm using one of these expansion tanks in a project, do you know of any way to use the coolant level monitor prongs to set off a custom light? As in, I have the expansion tank, I have an LED. How do I get it to turn on when the coolant is not touching both prongs? Apparently the prongs are usually connected to something which monitors resistance, and when the resistance gets too high, the light turns on. Creating a simple circuit to do that seems complex. Typically the job of a micro controller. Would be much easier if they connected when coolant dropped like float sensors work. I was thinking, I could just use a normally on relay and use the two level sensor contacts as the switch lines for the relay. As long as there is coolant, the relay is switched to off, meaning no light. Coolant drops too low, resistance becomes infinite, relay returns to normal on state, light goes on. My only concern is I will be passing current directly through coolant. Obviously a very small amount, typically in the 200mA or less range. Just not sure if that can have unintended consequences in terms of electrolysis. As long as neither contact is touching coolant, it shouldn't pass current through the whole cooling system. I realize there is a low chance you'll see this comment. Maybe I'll hit you up on social media sometime. Just figured it would pique your interest if you do see it. Forums were not helpful and I figured if anyone knew, it would be you. Thanks for the awesome videos!

[@802Garage]

I think part of the solution may be putting the relay in the power side of the level sensor wiring. Provided both sensor pins aren't touching coolant, resistance should be so high that the relay does not switch and therefore it should pass nearly zero current through the coolant. As an additional precaution, I could use a MOSFET instead of a relay. It should draw such low Amperage that current through coolant is a non issue, especially since the reservoir and connecting hoses are plastic. Since a MOSFET is Voltage switched, provided there is high resistance, it definitely shouldn't switch without coolant present. I'd need to make sure the resistance through coolant wasn't so high it would never switch though. At any rate, if you have more insight, please let me know!

[@rudolfhuijs4526]

Are you the guy who made a Scotty Kilmer parody video?

[@802Garage]

@@rudolfhuijs4526 That is indeed me!

[@rudolfhuijs4526]

@@802Garage That video made me laugh like mad all the way. Then at the end the gas tank goes nuclear and I was pissing. Cheers man!

[@802Garage]

@@rudolfhuijs4526 Hahaha thanks a megaton! Maybe I'll make another one someday. For now focusing on cool engine swaps and all that. :D

[@MarioRedd-wi7gb]

Thank you for this. hey my bottles is not hold coolant but no signs of leaks. The inside of my bottle is like pink dirt inside. How can i fix this

[@nikoabednego1734]

Please help i hv water coming out tru a reservoir breather on my vw polo while am drivin bt the car does not overheat ,fan turns on fine at 90 degres i changed the reservoir cap bt nothing changes what could be the cause

[@Mikeyk07002]

Question, my coolant looks dark and has a bit of foam or bubbles on the top. Will flushing it resolve this.

[@HumbleMechanic]

Might have to flush a few times but probably

[@brandonmazariegos1412]

MK4 I have boils and the coolant antifreeze presure and wanna come out. What do you think it's the problem?

[@FloridaDCSVideos]

Very easy to replace but i agree with some here, bad quality VW plastics. Have not had a car where this part cracked. The little nozzle on mine broke and the hose won't stay on. Wiki has some info that VW was consistently putting cheap plastics on their cars for years to save money and develop the Bugatti Veyron(claimed by the McLaren CEO).

[@derekkchung]

At what resistance of the coolant would the temp light start flashing? Is it temp related/calculated? Only the pink OEM coolant has the right resistance? What if RO water is added to the cooling system?

[@LynxStarAuto]

The tank only relays coolant level. Not temperature. Temperature comes from the coolant sensors located elsewhere in the system.

[@robertwilson6928]

Watching this after finding mine is leaking around the seam. Not running low but just gonna replace it since it does not cost much.

[@SilentMott]

My coolant was definitely below the line when my light came on and I checked for any residue around the wires and tubes, is it possible there is a leak somewhere else?

[@UomoPiccione]

SilentMott sure, waterpump or radiator

[@davidgruen7423]

SilentMott usually it is thermostat

[@stevenrhee4940]

Check your heater coolant flange

[@louismartinez213]

Can a crack on one of the hose plugs be a cause of a leak?

[@xavierdiazmcguire4667]

Had one fail and filled coils one and two full of coolant

[@evertminnebo4585]

Hi man! Learned a lot on this video! Unfortunately I have a problem with my cooling system and can't find an answer anywhere.. Everything in the cooling system of my VW T3 works perfect, except one thing. When my coolant level is low in the round bottle that you're holding, normally it pumps water from the other reservoir (the one that's easy to fill up without opening your engine/hood) but it stopped doing it.. Is it the blue cap that's failing?? Really can't find anything on the internet. Thanks a lot!!

[@HumbleMechanic]

Weird. Could be the cap.

[@evertminnebo4585]

@@HumbleMechanic I'll order one. Hopefully that's the problem. Thanks for the quick respond! 👍👍👍

[@HumbleMechanic]

No prob. That’s cheap and easy to replace. Just make sure the car is cooled down all the way

[@scramjet2000]

2005 jetta wagon tdi coolant return nipple broke off inside the hose at 265K miles. Loosen cap and close off return hose to get to destination then replace coolant reservior. Full flush and replace coolant.

[@EXOVCDS]

Gabriel Martins Which part of the brake fluid reservoir fails? I have never seen one fail.

[@HumbleMechanic]

***** I have seen lots of b5 resi fail when doing a pressure brake bleed, but that is about it.

[@robertgreenfield9051]

+HumbleMechanic LOL, I've had this happen and it is NOT fun. Big mess.

[@linuxwave]

Can anyone tell me how the overflow works in these VW engines? They don't seem to have a radiator spill cap to release too high pressure in the system

[@dxi8]

The black plastic part of the pressurized lid actually melted on mine while driving. Inside the bottle.

[@LastHumansTech]

Is filling a mk7 gti cooking system as simple as just filling this reservoir? No bleeder valves like old Honda’s?

[@HumbleMechanic]

You really need to use a bleeder. They are a pain to bleed

[@mingiasi]

a4 b5 1.9tdi afn. nothing leaks, does not over heat how ever when parked throws half or more bottle out via overflow? this happens while parked and not running. Bottle, cap swapped to new parts and are holding pressure as expected. No contaminants in coolant, no bubbles. Any ideas what the frick is going on with it?

[@gamthv]

I have the same problem on my 2015 Passat Tdi haven’t figured it out

[@joel561]

My 2006 VW Jetta 2.5L is getting the flashing red light for engine temperature. I suspect that it's this bottle, because first the engine doesn't overheat and stays at normal running temperature and stays there. Checked the coolant level and all is fine there, didn't see any leaks either... I think the level sensor is going bad, like you said it builds deposits over time?... Is there any way to clean the sensor or is it best to just buy a new bottle/sensor all together? Thanks for the video. very informative!

[@eponymous7910]

Buy a new coolant bottle + sensor and get a new maf sensor while you're at it. They're responsible for so many issues in VW/Audi land

[@JavierGomez-lh8uj]

is there a diy video on how to replace this part, cant seem to find it

[@HumbleMechanic]

+Javier Gomez there may be. It's one of those pretty straightforward things. 2 screws 2 clamps. Just be sure engine is cold and top the coolant off

[@rickreid81]

Great video! Thank you. Very helpful. I will be using Deutsche Auto Parts in Future. They have a store less than a hour from me.

[@HumbleMechanic]

Oh nice. I’m on the other side of NC

[@droge192]

On my 3rd one in 2 years. Always fails (cracks) in cold temps in winter.

[@GS-rs6es]

I have this problem now. 2004 Jetta V6. When I release the cap to the bottle the water starts to boil. I think the coolant has flowed back

[@wafi3187]

Cutest coolant expansion tank lol

[@macksonchison8868]

Wafi 31 what wrong if golf 6 is overfloating

[@kevinclass2010]

Looks like the death star or BB2

[@gplusgplus2286]

A good aftermarket bottle was about 7 euros. Oem is 35. Change the bloody things, they're cheqp.

[@christopherhaislet6460]

2005 beetle convertible gls 1.8t Coolant leaks out when outdoor temperature drops down. Gonna replace coolant bottle. Any other things I ought to look for? Will Fiberlock help ? Getting tired of this problem, have spent so much to .are this car run good !

[@Messy_Jesse]

I own a stage 3 VW that keeps going through radiators every 4 months or so. I'm carefully installing them and tape cardboard to the fins so they dont get poked on install... The car has aftermarket cooling fans. I used 2 relays and put them on switches... It has polar fis and I manually switch the fan on if it reaches 190° or so. I don't use AC. It throws a code for the cooling fans and AC. I want to code them out if possible but really need to figure out why my radiators keep failing. My best guess is an electrolysis issue but I cant find a vw video on this topic. Have you dealt with this before?

[@billd66]

I've noticed that the false "low coolant" alerts really tend to happen mostly on very cold days. I have an '01 Beetle with the 2.0. I had a few days this past winter that were below 10°F/-12C and got that false low coolant reading.

[@lorenzobeckmann3736]

ON THIS PART ISSUE: !!with my CC this bottle was rubbing against the mount, the left (looking into engine bay) engine mount has a black brackert which holds the washer bottle. this bracket, with very sharp edge, rubbing against lower portion of bottle---could easily wear through in time. jammed 1/8 piece of leather between to stop abrazion.

[@HumbleMechanic]

Wow never seen that

[@Drawing-photography]

I think ours cracked - going to have a go later at replacing it

[@davidgruen7423]

Last time I refilled the bottle cause the system just exploded when I broke a plastic coolant pipe joint. I filled the bottle to the correct level when cold before I start the car and drove it with the heat on full blast for 20 minutes. And the other day when I checked the fluid the level is below minimum. The question is, why didn’t the warning light came on?

[@HumbleMechanic]

It has to be lower than below min for the light to come on

[@davidgruen7423]

HumbleMechanic it was below minimum but while I was driving the day before the light never came on… weird.

[@angelramos4788]

My car randomly purged all my coolant through that overflow tube you mentioned, never had any temp problems before any thoughts?

[@HumbleMechanic]

Seen a head gasket do that a few times, also seen a few bottles fail that way

[@angelramos4788]

HumbleMechanic I don’t think it’s my head gasket. Filled the coolant back up and tried to see if I could get it to repeat and it’s been running fine for a month now since it happened. Thankfully happened in my driveway while idling so I was able to shut car off immediately

[@edsheeran2994]

Daryl Ramos did you ever find the solution? My car just did the same thing

[@JavierGomez-lh8uj]

If you have a leak, all you need to replace is the coolant container?