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The LT4 engine has two different cooling systems. The engine cooling system and the charge air cooling system (intercooler). They are separate from each other. If you are changing the fluid due to the 5 year/150K mile maintenance requirement then you need to change both systems.
The engine cooling system is basically the same as the LT1 while the Intercooler is more complicated. To drain the intercooler you will need to remove or partially remove the right front inner wheel well to gain access to the drain plug at the bottom of the intercooler reservoir. You will need to use a vacuum fill tool to get the air out of the charge air cooling system. For proper performance, the air gap at the top of the intercooler reservoir must be much smaller than the air gap that was there from the factory. There should be no more air at the top of the reservoir than two air bubbles the size of two US quarters. You can see the reservoir from under the hood by looking down forward of the air cleaner and outside of the hood rod. It is hard to get the air out of the system and it can take several hours of pulling a vacuum and refilling and running the pump motor for a minute or so each period of vacuum.
Here is my reservoir after the dealer mechanic spent a couple of hours bleeding the system per instructions from GM Engineering.
We couldn't get the air bubbles any smaller when using the ZR1 intercooler bleeding tools which Engineering said should be used. After we sent pictures to Engineering they thought the amount of air remaining was OK and that my on track high speed (150+ mph) power reduction issues would be resolved.
Remember that you can't use a 50/50 premix coolant in either the engine or charge air cooling systems. The C7 ratio is 60/40. 60% water and 40% antifreeze. Be sure to use DexCool Orange coolant.
I am attaching pages out of the 2016 FSM that show how to gain access to the drain port and use the original bleeding tool that was superseded by the ZR1 tool set.
You need to have the car hooked up to a battery charger that can provide sufficient current to run the charge air coolant pump while flushing the intercooler cooling system. If you don't you stand a good chance of draining the vehicle battery.
anyone know the procedure for the zo6 coolant flush on c7 zo6. is it different from the base c7?
thanks
Not that i know of.
Open petcock located front driver side (minor PITA to get to). Let cooling system drain. If you want insert some compressed air into coolant fill port to force all fluid out (not really necessary)
Refill using a vacuum fill attachment if available. If not available just refill and the watch coolant temp as you may have to burb it a few times to get all air pockets out.
To burb it just warm coolant up, let cool, open fill port and add more coolant . Repeat this a few times until the warm coolant temperature stabilizes to normal (190F or so with stock thermostat) and coolant fill port takes no more coolant to top off.
I'm sure there are other methods but this works just fine in my experience.
The LT4 engine has two different cooling systems. The engine cooling system and the charge air cooling system (intercooler). They are separate from each other. If you are changing the fluid due to the 5 year/150K mile maintenance requirement then you need to change both systems.
The engine cooling system is basically the same as the LT1 while the Intercooler is more complicated. To drain the intercooler you will need to remove or partially remove the right front inner wheel well to gain access to the drain plug at the bottom of the intercooler reservoir. You will need to use a vacuum fill tool to get the air out of the charge air cooling system. For proper performance, the air gap at the top of the intercooler reservoir must be much smaller than the air gap that was there from the factory. There should be no more air at the top of the reservoir than two air bubbles the size of two US quarters. You can see the reservoir from under the hood by looking down forward of the air cleaner and outside of the hood rod. It is hard to get the air out of the system and it can take several hours of pulling a vacuum and refilling and running the pump motor for a minute or so each period of vacuum.
Here is my reservoir after the dealer mechanic spent a couple of hours bleeding the system per instructions from GM Engineering.
We couldn't get the air bubbles any smaller when using the ZR1 intercooler bleeding tools which Engineering said should be used. After we sent pictures to Engineering they thought the amount of air remaining was OK and that my on track high speed (150+ mph) power reduction issues would be resolved.
Remember that you can't use a 50/50 premix coolant in either the engine or charge air cooling systems. The C7 ratio is 60/40. 60% water and 40% antifreeze. Be sure to use DexCool Orange coolant.
I am attaching pages out of the 2016 FSM that show how to gain access to the drain port and use the original bleeding tool that was superseded by the ZR1 tool set.
You need to have the car hooked up to a battery charger that can provide sufficient current to run the charge air coolant pump while flushing the intercooler cooling system. If you don't you stand a good chance of draining the vehicle battery.
Bill
Last edited by Bill Dearborn; Oct 15, 2022 at 04:29 PM.
UGH,but thanks Bill. I had posted on the C7 discussion that I accidentally poured almost a half quart of oil in the coolant tank, realized it then pumped it out.
removed tank and washed it out with dawn and put it back. Took it for two 10 mile drives with no problems but next day when I open cap can see slight sediment floating on top of coolant.I skimmed it out with turkey baster both times and replaced with new coolant.Had scholder surgery Thursday so skimming and refilling is over for now
So 99k question is am I ok?
Thanks
Bob
Didn’t want to start a new thread but what is the approximate dealer cost of flushing (and bleeding) both systems? I’m nearing year 5 and I see the owner’s manual recommends flushing at 5 years.
pretty sure my 16' has the stock stuff still and not looking forward to replacing the coolant in either / both. but between that and the brake fluid is all I have left to replace.
Didn’t want to start a new thread but what is the approximate dealer cost of flushing (and bleeding) both systems? I’m nearing year 5 and I see the owner’s manual recommends flushing at 5 years.
I just did my 15 a few months ago.
I'm sure some guys will say there's additives that decay over time, etc, which very well may be true.
but what I can say is mine came out looking literally brand new as if it was filled the day before.
I still went through with it anyway and did a few fills, warm ups, drains, refills, etc, to get it all exchanged out.
But it was crystal clear with a tint of orange just like new fluid
Didn’t want to start a new thread but what is the approximate dealer cost of flushing (and bleeding) both systems? I’m nearing year 5 and I see the owner’s manual recommends flushing at 5 years.
The engine cooling system is similar to any other Chevy engine and should be one of the dealer's normally advertised services. However, the Charge Air Cooling System requires more time and you will need to be on top of them requiring they make sure they get most of the air out of the system. That is because the cars were delivered from the factory with a large air gap at the top of the reservoir so everybody references that level when refilling. However, performance issues with charge air cooling demonstrated to GM Engineering the air had to be removed from the system to get the best performance when driving on a track. On the street, an owner will never notice the difference. When the dealer did the warranty charge air bleed on my Z06 after GM Engineering instructed them to get the air out it took about 2 hours of bleeding time. There was no drain and refill, just bleeding.
I just did my 15 a few months ago.
I'm sure some guys will say there's additives that decay over time, etc, which very well may be true.
but what I can say is mine came out looking literally brand new as if it was filled the day before.
I still went through with it anyway and did a few fills, warm ups, drains, refills, etc, to get it all exchanged out.
But it was crystal clear with a tint of orange just like new fluid
Same here, mine looks new. I have a ‘19 originally bought in 5/2018. I got it used in 6/2022 but I’d imagine the owner never did anything. I’m at 8500 miles currently but it’s hibernating. I never changed out coolant in other cars but being that these are performance cars I’m much more inclined to do so.
Originally Posted by Bill Dearborn
The engine cooling system is similar to any other Chevy engine and should be one of the dealer's normally advertised services. However, the Charge Air Cooling System requires more time and you will need to be on top of them requiring they make sure they get most of the air out of the system. That is because the cars were delivered from the factory with a large air gap at the top of the reservoir so everybody references that level when refilling. However, performance issues with charge air cooling demonstrated to GM Engineering the air had to be removed from the system to get the best performance when driving on a track. On the street, an owner will never notice the difference. When the dealer did the warranty charge air bleed on my Z06 after GM Engineering instructed them to get the air out it took about 2 hours of bleeding time. There was no drain and refill, just bleeding.
Bill
Thanks. I think I can handle the regular flush but it’s the charge air cooling flush and bleed that has me nervous. I’m a guy that knows his limitations and after reading all of your info I’m not sure it’s something I’d care to do myself. I don’t track mine but I did look and the current air bubbles aren’t too big but probably larger than spec.
I struggled getting the intercooler bled for years, so much so that I finally went about R&D'ing a solution that didn't require lifting the car to awkward angles or constant tinkering and involvement from the person performing the bleed. Just a solution that the end user could plug in, press go, and the system would Auto bleed completely and fully.
That's where The Cooler Bleeder came into play. Check it out if it's something you decide to do on your own as it's more or less fail proof successful bleeding of the intercooler circuit / CAC, or find someone in your area that has one already
I struggled getting the intercooler bled for years, so much so that I finally went about R&D'ing a solution that didn't require lifting the car to awkward angles or constant tinkering and involvement from the person performing the bleed. Just a solution that the end user could plug in, press go, and the system would Auto bleed completely and fully.
That's where The Cooler Bleeder came into play. Check it out if it's something you decide to do on your own as it's more or less fail proof successful bleeding of the intercooler circuit / CAC, or find someone in your area that has one already
So I don't have to reinvent the wheel is there a procedure to flush the intercooler fluid using the Cooler Bleeder I have without removing parts from the car and using the drain valve on the intercooler reservoir?
So I don't have to reinvent the wheel is there a procedure to flush the intercooler fluid using the Cooler Bleeder I have without removing parts from the car and using the drain valve on the intercooler reservoir?
atljar's solution works really well. I own a Cooler Bleeder.
atljar's solution works really well. I own a Cooler Bleeder.
I used mine to purge air from the system. My question is can the system suck the fluid out of the system without pushing it back in. During normal air removal the system sucks some out ands then pushes it back in plus some from the initial tank fill.to replace the air that was purged...
I used mine to purge air from the system. My question is can the system suck the fluid out of the system without pushing it back in. During normal air removal the system sucks some out ands then pushes it back in plus some from the initial tank fill.to replace the air that was purged...
I'm not sure about using it to purge the system. I'd pm atljar and ask him.
I used mine to purge air from the system. My question is can the system suck the fluid out of the system without pushing it back in. During normal air removal the system sucks some out ands then pushes it back in plus some from the initial tank fill.to replace the air that was purged...
You can use The Cooler Bleeder as a flush machine, but the intercooler/CAC circuit is not ideal for machine flushing because of the very small hose diameter sizes. This comment will make more sense if you know how standard coolant flush machines work.
Most typical coolant flush machines are able to flush systems by collapsing the coolant hoses under vacuum and displacing that fluid. Because the hoses collapse, this effectively lessens the cooling system's capacity and that displaced coolant is pushed out of the system into the coolant flush machine. Since engines have large diameter hoses and lots of them, you (or a technician) are able to get a fair amount of fluid exchanged from the system. Any volume of coolant that is in a fixed volume location (inside the block, radiator, waterpump, heatercore etc) however will continue to hold coolant and wont be flushed out. In other words, a these type of machines are no where close to a 100% coolant exchange. You could use The Cooler Bleeder for a similar process, but the amount of coolant exchanged would be small because of the limited amount of hoses and their relatively small diameter.
There are two ways you can do high quality flush on the CAC systems.
Method 1) Remove one of the hoses from the front heat exchanger and remove the bleeder port fitting. This will allow the system to gravity drain. Catch the drained coolant and dispose of it legally/ethically. Bleed and refill the system with the correct 40/60 dexcool mix using The Cooler Bleeder. CONS: Those hoses are possible, but awkward, to reach from the engine bay. Will take some swearing and fidgeting and some long reach pliers. There will be a small amount of old coolant left over in the system (not enough to worry about IMO) PROS: You can refill the system with a precise percentage mixture of antifreeze and less mess than method 2
Method 2) Remove one of the quick connects on the super charger. These are easy to take off. Take an old piece of heater hose and slide it over the supercharger male fitting. Route the other end of the heater hose and direct it into a 5 gallon bucket on the floor. Take a garden hose and press it up against the vehicles CAC hose you just disconnected from the super charger. Turn on the hose and force water through the system. It will start pumping out heater hose and into the bucket. Run water until it turns clear. Dispose of coolant as noted above. The system is now pure water, so you will need to get some out to make room for antifreeze. You can use compressed air to blow in the heater hose and pump out some of the water or use The Cooler Bleeder to activate the cars CAC pump to pump it out. Remove the heater hose and reconnect the quick connect hoses. Now you need to ensure to get the system freeze protection back to the suggested 40-60 mix. If everything is stock, the system holds 4.5 qts of liquid. That means you need to add 1.8 qts of PURE coolant to the system. Add the 1.8qt to The Cooler Bleeder and let its do its thing. You should be able to get the system to take that completely in. Any additional coolant added to The Cooler Bleeder to finish the bleeding should be pure water. Try to only add the bare minimum amount to the pot so that you dont over dilute the mix. PROS: Easier access to the hoses to disconnect and the best quality flush. CONS: The end percentage mixture may not be absolutely perfect. Messier process than method 1
TLDR: The CAC system doesn't have enough volume in collapsible locations to be ideal for a vacuum machine flush. Other methods outlined above.
Hope that's helpful! Dont hesitate to reach out with any follow ups or checkout the website www.coolerbleeder.com
You can use The Cooler Bleeder as a flush machine, but the intercooler/CAC circuit is not ideal for machine flushing because of the very small hose diameter sizes. This comment will make more sense if you know how standard coolant flush machines work.
Most typical coolant flush machines are able to flush systems by collapsing the coolant hoses under vacuum and displacing that fluid. Because the hoses collapse, this effectively lessens the cooling system's capacity and that displaced coolant is pushed out of the system into the coolant flush machine. Since engines have large diameter hoses and lots of them, you (or a technician) are able to get a fair amount of fluid exchanged from the system. Any volume of coolant that is in a fixed volume location (inside the block, radiator, waterpump, heatercore etc) however will continue to hold coolant and wont be flushed out. In other words, a these type of machines are no where close to a 100% coolant exchange. You could use The Cooler Bleeder for a similar process, but the amount of coolant exchanged would be small because of the limited amount of hoses and their relatively small diameter.
There are two ways you can do high quality flush on the CAC systems.
Method 1) Remove one of the hoses from the front heat exchanger and remove the bleeder port fitting. This will allow the system to gravity drain. Catch the drained coolant and dispose of it legally/ethically. Bleed and refill the system with the correct 40/60 dexcool mix using The Cooler Bleeder. CONS: Those hoses are possible, but awkward, to reach from the engine bay. Will take some swearing and fidgeting and some long reach pliers. There will be a small amount of old coolant left over in the system (not enough to worry about IMO) PROS: You can refill the system with a precise percentage mixture of antifreeze and less mess than method 2
Method 2) Remove one of the quick connects on the super charger. These are easy to take off. Take an old piece of heater hose and slide it over the supercharger male fitting. Route the other end of the heater hose and direct it into a 5 gallon bucket on the floor. Take a garden hose and press it up against the vehicles CAC hose you just disconnected from the super charger. Turn on the hose and force water through the system. It will start pumping out heater hose and into the bucket. Run water until it turns clear. Dispose of coolant as noted above. The system is now pure water, so you will need to get some out to make room for antifreeze. You can use compressed air to blow in the heater hose and pump out some of the water or use The Cooler Bleeder to activate the cars CAC pump to pump it out. Remove the heater hose and reconnect the quick connect hoses. Now you need to ensure to get the system freeze protection back to the suggested 40-60 mix. If everything is stock, the system holds 4.5 qts of liquid. That means you need to add 1.8 qts of PURE coolant to the system. Add the 1.8qt to The Cooler Bleeder and let its do its thing. You should be able to get the system to take that completely in. Any additional coolant added to The Cooler Bleeder to finish the bleeding should be pure water. Try to only add the bare minimum amount to the pot so that you dont over dilute the mix. PROS: Easier access to the hoses to disconnect and the best quality flush. CONS: The end percentage mixture may not be absolutely perfect. Messier process than method 1
TLDR: The CAC system doesn't have enough volume in collapsible locations to be ideal for a vacuum machine flush. Other methods outlined above.
Hope that's helpful! Dont hesitate to reach out with any follow ups or checkout the website www.coolerbleeder.com
Thanks. As soon as it warms up around here I'll do method 2.
The info above is very good .
I use distilled water not tap water.
Our tap water contains lots of calcium.
I use red dye in the rad and blue dye in the intercooler to
identify each system in case of a leak.
