Hybrid Specific Coolant Burping Differences?

Hey all, I just had the 6.0 rebuilt and thrown back together. I plan to fill and burp the coolant system tomorrow. I understand that the coolant reservoir is split in two for both the primary engine coolant + radiator and the hybrid control module + radiator.


My question is, is there anything specific about filling/burping the coolant with the additional hybrid coolant system? If it matters, I am pulling vacuum on the entire system before filling.


I wouldn't think so but in the manual on page 6-11 it says "If the DMCM coolant is empty , the vehicle must be serviced by your dealer and a special fill procedure must be followed. Attempting to fill the DMCM cooling surge tank yourself when the fluid level is empty can damage your vehicle. Your vehicle must be serviced."

I don't have access to the oem procedure but I replaced mine when I replaced all the hoses. the hybrid side has electric pumps that run with the key forward and the tank is the high point. do it seemed to purge air fine. I have a feeling the warning refers to the type of fluid. you have to make sure it's electric car compatible. I just bought some a while back, and I don't remember if it's a different part number, or if gm has just switched all cars to the same coolant these days. since it's just a 50/50 mix of dex cool but the water is what's important. it's gotta be some deionized water used, or you might lose voltage containment over time and the ecm sees it and shut the system down.(the whole truck dies) same with the ac. being you had the engine out, if you opened the ac, make sure you use electric compressor oil. it's POE, not the standard pag. as pag can conduct.


being that you're vacuum filling anyways, just use the correct coolent and you'll be fine. these days a lot of brands make it, but I personally just ordered a gallon off rock auto. cheaper than the dealer, but I did have a shipping issue, the first box leaked and FedEx disposed it and I had to get them to re ship it. so the quickest safest is to hit a local dealer parts counter and ask nicely if they can match or get close to matching the gm parts direct price. some will.

details on your build? not a lot of people drive into working on or rebuilding engines on theses. it's always interesting to hear how it goes.


the other thing they might be talking about is if you find the tank empty during a check, as in there's a leak in the system. you keep adding coolent but it's leaking in the inverter and damaging it.

on the next hybrid newer gm built, the volt. if the hybrid side coolent take hits the low coolent sensor, it sets a code disabling the car until someone with a dealer level scanner can clear it. meaning they went thru the checks. since the coolent runs thru the battery and all the electronics on that one. they want a tech to check for leaks in some battery inspection holes so users doing just keep filling the battery with coolent from a leak.

gm definitely took the hybrid cooling very serious

here's what my software says.

should be fine, just run the pump to work the air put before starting.