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I opened my Bolt's hood yesterday to show family, and I noticed one of the coolant levels appeared low. There are 3 of them, with a red goop inside. The top middle one, as shown in the picture below, seems to be much lower than the line. Is this common or OK? I called two dealers who had no idea. How does your levels look? If I wanted to refill it, what type of coolant would I use?

 

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Checking the owners manual, page 255, shows this is the coolant reservoir for "cabin heating". Doesn't seem to critical, but it'd be nice to just refill it on my own with... something.
 

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From the manual, page 316:

Use Only Premix DEX-COOL® Coolant (GM Part No. 12378390, in
Canada 10953456

From Volt forum:

"Dexcool is still ethylene glycol just like the old green stuff but with an additive package that makes it less reactive to certain metals (especially aluminum and aluminum alloys) less corrosive to modern OEM rubber coolant hoses (not necessarily to cheap Chinese replacement hoses) certain pump seals, AND will also increase it's service interval up to 5-years 150,000 miles."

https://www.walmart.com/ip/Prestone-Dex-Cool-Extended-Life-Antifreeze-Coolant-1gal/16889200
 

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Most of the cars I have owned had max and min fill lines. There is only one line on the reservoirs on the Bolt. All of them are filled several inches above that line on mine, so I am going to guess that is the minimum line. I would definitely fill it, with the approved coolant, to above that line. You don't want air in any modern coolant system. It should not lose any after that. If it does, get to the dealer, as you'd have a leak.
 

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Discussion Starter #5
Thank you guys, big help! DEX-COOL looks like the right stuff. It is in a very difficult spot to fill, so I will also need a flexible funnel. I will fill it up to the line.
 

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There is a little tube that looks like would drain the coolant if it overfilled while hot... so, might cause a little internal mess but otherwise not a big deal. I plan on filling to the line (maybe a bit higher).
 

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Yeah. The systems for ICE are pressurized to raise the boiling point above 212F. If anything in the Bolt ever got above 195F, that would indict a serious problem.
 

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I would take the car into the dealer. The coolant should not be low already and that may mean there is a leak somewhere. I mean it is possible it didn't get filled correctly at the factory but I would still think it prudent to have the dealer check it over to make sure there isn't a leak.

There is another thread going right now that was about someone who did have a leak.
 

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Discussion Starter #10
I'm planning on filling it up & monitoring it. If it seems to drop again, then I have a strong case it is a leak which will definitely require some dealership intervention.
 

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Bolt EV OM p. 254:

A coolant loss could indicate a problem. Have it inspected and repaired by your dealer.
{and}
Hybrid Cooling System Pressure Caps
The hybrid cooling system reservoirs have tamper resistant pressure caps. The coolant should only be serviced by a qualified technician.
Chevrolet Bolt EV Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-10122739) - 2017 - CRC - 10/3/16 V

Will self-servicing your coolant level void any of your warranty protections?
 

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Bolt EV OM p. 254:

A coolant loss could indicate a problem. Have it inspected and repaired by your dealer.
{and}
Hybrid Cooling System Pressure Caps
The hybrid cooling system reservoirs have tamper resistant pressure caps. The coolant should only be serviced by a qualified technician.
Chevrolet Bolt EV Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-10122739) - 2017 - CRC - 10/3/16 V

Will self-servicing your coolant level void any of your warranty protections?
It shouldn't as the caps are tamper proof, not sealed. If they were sealed they could void your warranty. Pretty much the same as if you change your own oil. Also notice the use of should in should only be serviced. If it was in fact a warranty requirement it must say must only be serviced by a qualified technician.

Granted you should keep proof that you in fact used the correct coolant as using the incorrect coolant could void the warranty as it relates to the parts in contact with said coolant.
 

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I just went out and checked one of the tamper proof caps. You have to depress it to unscrew it, like a tamper proof aspirin bottle. Only, unlike one of those, you don't need a pliers to get it off. :)

When you screw it back on, it gives one click, like modern gas caps, to indicate it is tight. Not much torque required for opening or closing. The cap says 5 psi. If that is all the pressure the system sees when it is hot, it is not getting very warm.
 

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In a technical article somebody posted here an engineer on the product described it as "very standard, very traditional 50/50 glycol/water"

Personally I'd buy the GM blessed coolant, but sounds like it's nothing special.
 

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DO NOT USE ANYTHING other than the required coolant. These systems are monitored for isolation faults.
If you use anything else, the minerals in the water/coolant will trigger a fault code and shut the car down. You'll have a car that's not worth a dime because the system that is damaged and will require a 100% replacement.

DO NOT BE A DIY'er with the wrong information and the wrong coolant. You'll regret it!!!

Distilled water and GM's EV coolant only. Most cars don't get this reservoir checked and they have an air pocket. It's not an indication of a leak unless you fill it and monitor it with a continued loss. New cars can and will have air pockets.
 

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DO NOT USE ANYTHING other than the required coolant. These systems are monitored for isolation faults.
If you use anything else, the minerals in the water/coolant will trigger a fault code and shut the car down. You'll have a car that's not worth a dime because the system that is damaged and will require a 100% replacement.

DO NOT BE A DIY'er with the wrong information and the wrong coolant. You'll regret it!!!

Distilled water and GM's EV coolant only. Most cars don't get this reservoir checked and they have an air pocket. It's not an indication of a leak unless you fill it and monitor it with a continued loss. New cars can and will have air pockets.
So there is a special EV coolant version of DexCool? It's not just the same DexCool radiator fluid used in other GM cars?
 

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Also, to DrDiesel, what kind of funnel, or filling device do you guys use to service these reservoirs that Chevy so poorly provided access to?
 

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So there is a special EV coolant version of DexCool? It's not just the same DexCool radiator fluid used in other GM cars?
I don't think it anything "special" just for an EV. This is the part number specified in the manual, Premix DEX-COOL Coolant GM Part No. 12378390. It lists as being used by trucks and hybrids.

dex-cool

One interesting thing with this one is that it is already premixed with the deionized water, it says not too dilute further.
 

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Also, to DrDiesel, what kind of funnel, or filling device do you guys use to service these reservoirs that Chevy so poorly provided access to?
I don't have a Bolt so I can't be sure that this applies, but in other cars where fluid reservoirs are nestled way back underneath the HVAC air plenum there's often a plastic piece of the plenum that can be removed to make it easy to fill the reservoir.
 
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