Driving Without Coolant Reservoir Cap
- Thread starter garystaven88
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Looks like a separate system for cooling the hybrid battery.
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- Dec 24, 2023
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The other reservoir has to do with the Hybrid system. I researched this and it is normal to be blue in that reservoir.
I would have the regional service manager put your conversation in writing,I'm unsure if they created problems,the techs and the dealer service manager need to learn to correct their issues,not ignore them
The rubber glove is an excellent idea. It can expand and contract as needed. Good thinking.
4wd
$50 site donor 2026
Yes, our Fusion Hybrid had that second tank …
4wd
$50 site donor 2026
You can Google pressurized coolant tank and they pop up in dozens of shapes/sizes - very telling …
Your pics confirm it's unpressurized, so as others have said fashion a temporary cover to ensure dirt stays out and drive away.
Neglecting coolant related things is common. I bought a 10 yo Lexus in 2016 and it was dealer serviced. When I got home it had ZERO coolant in the reservoir and ZERO that could be seen in the radiator.
I thought blown head gaskets but no. Evaporation.
Why it was never checked? Toyota interval was 10 years / 100k miles. Car was reaching 10/81k so no need to and was never checked in its entire life.
I also realized that in addition to being inaccessible (air intake obstructs the radiator and reservoir, the tank gets stained so one can’t even see the level, it appears as full—really bad design).
So while the dealer answer is disappointing for sure, it likely would not have any effect unless something such as debris could fall in. It’s not a closed system like BMW where such an answer would be moronic
My .02
I thought blown head gaskets but no. Evaporation.
Why it was never checked? Toyota interval was 10 years / 100k miles. Car was reaching 10/81k so no need to and was never checked in its entire life.
I also realized that in addition to being inaccessible (air intake obstructs the radiator and reservoir, the tank gets stained so one can’t even see the level, it appears as full—really bad design).
So while the dealer answer is disappointing for sure, it likely would not have any effect unless something such as debris could fall in. It’s not a closed system like BMW where such an answer would be moronic
My .02
100K is the change interval. I promise the manual says to inspect the fluid every service interval. This is for a 2019 Rav4, with 100K coolant change interval.
Which might mean the tech was actually doing his job when he lost the cap?
Another tip off of a pressurized tank can be more than one hose emanating from the tank and also perhaps the absence of a conventional radiator cap on the radiator. Hot coolant is continuously circulated through the tank of my Suburban.
Contrary to my initial assumptions in Post #10 (prior to seeing the photos), the '24 Tucson Hybrid does indeed have a pressurized cooling system. The pictogram on the missing cap clearly shows not to open the cap when the coolant is hot due to pressurization.
As such, I would advise against driving the vehicle without the cap installed. The obvious risk is loss of coolant due to evaporation (which appears to have occurred) and the potential for introducing debris. However, since the cooling system was engineered to operate under positive pressure, there is some potential (perhaps minor) risk that overheating could occur due to cavitation within the system. If an air bubble pocket forms at the coolant temperature sensor location, the temperature gauge won't display any temperature increase.
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To pile on our hapless dealer tech, they often have to fill out an 87-point inspection checklist when they do any service, as a customer service (not really) and as an opportunity for upsales (bingo). Tech probably pulled the cap so he could dip a test strip that shows degraded coolant by changing to a particular color.
OP should look around the engine compartment, down cracks etc, it could have fallen down somewhere. And he should be raising cain to get a replacement cap or tow in for service. If his manual says not to drive without the cap, bingo, golden ticket to a free tow.
OP should look around the engine compartment, down cracks etc, it could have fallen down somewhere. And he should be raising cain to get a replacement cap or tow in for service. If his manual says not to drive without the cap, bingo, golden ticket to a free tow.
I totally agree it’s not desirable and maybe with my own car I would act differently. But the OP’s original pic was clearly the coolant and not the inverter cap. I do think there would be evaporation as a result over time. One should be able to technically drive with ZERO coolant in the overflow. Again not designed that way but works. It’s the job of the radiator cap to allow overflow, and vacuum as well when engine cools.
What we’re talking about is the overflow cap, not the radiator cap. Again my .02
What we’re talking about is the overflow cap, not the radiator cap. Again my .02
You are describing a traditional non-pressurized overflow system that has an overflow bottle which has a unsealed cap along with a sealed radiator cap with an integral over-pressurization relief valve (typically rated ~12-16 psi) that vents to (and siphons back from) the overflow reservoir.
The OP's Tucson has a pressurized cooling system that only has one cap to maintain pressure...and that cap is now missing. There is no additional cap on the radiator itself. As such, his situation would be similar to driving a car with a non-pressurized system without a radiator cap.
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I stand corrected. Then it's awful on the dealership's part. Dunno if it was discussed or not, exactly how does it become missing?
SammyChevelleTypeS3
$50 site donor 2023
REPORT this foolishness ASAP.
This is IMHO truly some very dumb and arrogant attitude "could care less about their customers" & behavior. Report them to Hyundai Corporate offices plus to the Dealership owner.
I would first call the dealership (Main Manager) and explaining to them you would like to know his reaction to the way his people treated you. Then that you will hold his dealership + service department (their very own servicing shop) totally responsible for any issues. You did not remove or lose the cap did you? So...... who did?
I would then ask, Would he send any of his own family members out on the road under similar situation?
If they truly cared for their customers, there is no way on earth he could not have quickly and caringly remedied this situation.
They could easily and simply could have called one of their local suppliers or even a close by Hyundai dealer for a repayable favor and have had an OEM or any suitable temporary cap (better than no cap!?) put in place until a Hyundai cap can be obtained.
Of course many, I am sure will say - "no , an oem cap is not really required" which I agree with.
The poor treatment you all received is what I can not accept. Unfortunately I am hearing more and more stories that sound very similar as of late. So what we have going on is , prices of vehicles are sky rocketing to near unobtainium prices along with the rising costs of service work while the quality of many parts and the quality of work is going in the opposite direction. Not good for consumers who can not DIY.
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