[George_L]

I'm at 5 years now on my 2014 Z51. I guess it's time to change the coolant. I haven't seen any how-to threads so I thought I would ask for any tips or warnings. It looks like my petcock is on the driver's side of the radiator at the bottom but there is an opening in the bottom near the petcock that looks like a drain aimed straight down. If the hole is the drain then kudos to the engineers for making it easy to drain without spilling. I assume that the valve only turns 1/4 or 1/2 of a turn counterclockwise to open. Can anyone confirm this? I don't expect to get a full drain by just opening the valve with the thermostat closed; am I correct? Since it is a sealed system, my thought was to open the valve, add water to the reservoir and start the engine. Keep adding water until it is flowing clear, then start adding the 60/40 Dexcool mix until I see a change from clear to red. Am I overthinking this? Does this method make sense? Is there an easier/better way? Thanks in advance for your help. I enjoy doing the basic maintenance on the car and I've gotten a lot of great advice from the forum that has made ownership much more fun.

 

[West Ham Utd]

I would personally skip the fresh water fill part of your flush , as without doing a full drain afterwards, you could end up with an over diluted coolant. I would just drain the radiator (removing the pressure cap on the expansion tank should help draining), then fill with fresh fluid (keep the pressure cap off & run engine, as it allows the air to be "burped" from the system more easily. Keep an eye on the fluid level & be prepared to add more as needed. Once you see the fluid level hold steady & slightly rise, shut off engine & replace pressure cap).
Go for a short drive & get coolant up to temp, then once cooled repeat drain/ fill. This isn't a true flush, but rather just trying to replace as much old fluid with new via "dilution" of old fluid. I would use distilled water to mix with the Dexcool, but that's just me. HTH

 

[Mobius]

I use the technique West Ham mentions, as well.

The only difference is that I collect all the drained radiator fluid, measure it, and replace with an equal volume of fresh orange Dexcool coolant.

 

[West Ham Utd]

Mobius, great tip. I do the same for changing transmission fluids, but didn't even think to bother measuring the drained coolant for a fluid change, Cheers

 

[George_L]

I use the technique West Ham mentions, as well.

The only difference is that I collect all the drained radiator fluid, measure it, and replace with an equal volume of fresh orange Dexcool coolant.

Mobias, thanks for the suggestion. I assume when you fill with orange Dexcool you are using a properly diluted solution?

 

[George_L]

I would personally skip the fresh water fill part of your flush , as without doing a full drain afterwards, you could end up with an over diluted coolant. I would just drain the radiator (removing the pressure cap on the expansion tank should help draining), then fill with fresh fluid (keep the pressure cap off & run engine, as it allows the air to be "burped" from the system more easily. Keep an eye on the fluid level & be prepared to add more as needed. Once you see the fluid level hold steady & slightly rise, shut off engine & replace pressure cap).
Go for a short drive & get coolant up to temp, then once cooled repeat drain/ fill. This isn't a true flush, but rather just trying to replace as much old fluid with new via "dilution" of old fluid. I would use distilled water to mix with the Dexcool, but that's just me. HTH

Thank you for the help. I already purchased 6 gallons of distilled water.

 

[Mobius]

Mobias, thanks for the suggestion. I assume when you fill with orange Dexcool you are using a properly diluted solution?

Yes, I dilute the Dex-Cool concentrate with distilled water.

Per my 2014 owner's manual (pg 9-7), "Maintain a mixture of 40% DEX-COOL coolant and 60% clean, drinkable water to optimize engine performance."

 

[Busa Dave]

To the OP----I always flush Twice*(did it 3 times on the Ram Cummins last year until water came out clean no soapy bubbles) with distilled water before adding back the pre missed coolant. Takes a little more time but I am overkill on everything.

 

[George_L]

I finally got around to flushing my coolant system and I want to share my experience since there seems to be very little info on the forums or the web for a C7. Thanks to all that provided advice. It went smoothly and I was probably over thinking the task as usual. Here is what I did. I'm not saying this is the best way or even the correct way, it's just what I did.

1. Locate the coolant reservoir.

2. Remove the lid (make sure engine is cool as the coolant can be under pressure when hot)

3. Place a drain pan large enough to hold at least 2 gallons under the radiator drain (I also put newspaper under the drain pan). The drain is on the driver's side and facing directly down. You can only see it from under the car. It is directly below the petcock valve shown in step 4. You can see coolant flowing from the drain in this picture. The picture is taken looking up from under the car.

4. Now locate the petcock (valve). It is white plastic and located on the driver's side of the radiator at the bottom. It can easily be seen and reached from above the car. I did need to use my left hand to reach it. The valve is open in these pictures.

6. Open the valve by turning it counterclockwise. Mine was only finger tight. Turning the petcock 3.5 turns CCW started the flow. I turned it an additional 1/2 turn for a total of 4 complete revolutions to drain.
Make sure the coolant is hitting the drain pan.

It took about 10 minutes to drain. I measured 7 quarts of coolant.

7. Close the valve. Replace the drained fluid with an equal amount of distilled water.

8. Start the engine (I left the coolant cap off) and idle until the engine reaches operating temperature.

9. Repeat the drain (7 quarts drained this time also) and fill with distilled water again.

10. Run engine again until it reaches operating temperature.

11. I repeated steps 7 and 8 one more time. This time the drained fluid only had a very light orange color.

12. Close the valve. Wipe off any coolant under the car. And add 4.5 quarts of Dexcool to the reservoir. The coolant capacity is 11.3 quarts and GM recommends a 60/40 water to coolant ratio. I was only able to find gallon jugs of Dexcool so I have 3.5 quarts left over. It didn't all fit until I let it sit about 5 minutes. Top off with distilled water. Wait 5 minutes and fill to the correct level with more distilled water.

13. Install the reservoir cap. Run the engine again until operating temperature is reached. Let cool and top off fluid with more distilled water.

I still need to take the car for a good ride and check the level again. It was very easy but a little time consuming. Also make sure to dispose of the old coolant properly. I hope this makes things a little easier for someone. The coolant is supposed to be changed at 5 years (there is also a mileage limit which would require earlier replacement) so the 2014's are due.

 

[jsvette]

Very nice and clear write-up George. Thank you! You are correct in that the Owners Manual maintenance chart does indicate changing it out at 150k miles or 5 years, whichever comes first.

 

[Tom99]

Thank you George.

 

[George_L]

Thank you George.

You are welcome Tom. I'm glad I can help for a change. I've gotten so much advice from others on the forum that has helped me do a lot of my own maintenance.

 

[2ndvette]

I finally got around to flushing my coolant system and I want to share my experience since there seems to be very little info on the forums or the web for a C7. Thanks to all that provided advice. It went smoothly and I was probably over thinking the task as usual. Here is what I did. I'm not saying this is the best way or even the correct way, it's just what I did.

1. Locate the coolant reservoir.
View attachment 266232

2. Remove the lid (make sure engine is cool as the coolant can be under pressure when hot)
View attachment 266234

3. Place a drain pan large enough to hold at least 2 gallons under the radiator drain (I also put newspaper under the drain pan). The drain is on the driver's side and facing directly down. You can only see it from under the car. It is directly below the petcock valve shown in step 4. You can see coolant flowing from the drain in this picture. The picture is taken looking up from under the car.
View attachment 266238

4. Now locate the petcock (valve). It is white plastic and located on the driver's side of the radiator at the bottom. It can easily be seen and reached from above the car. I did need to use my left hand to reach it. The valve is open in these pictures.
View attachment 266240
View attachment 266242

6. Open the valve by turning it counterclockwise. Mine was only finger tight. Turning the petcock 3.5 turns CCW started the flow. I turned it an additional 1/2 turn for a total of 4 complete revolutions to drain.
Make sure the coolant is hitting the drain pan.
View attachment 266236

It took about 10 minutes to drain. I measured 7 quarts of coolant.

7. Close the valve. Replace the drained fluid with an equal amount of distilled water.

8. Start the engine (I left the coolant cap off) and idle until the engine reaches operating temperature.

9. Repeat the drain (7 quarts drained this time also) and fill with distilled water again.

10. Run engine again until it reaches operating temperature.

11. I repeated steps 7 and 8 one more time. This time the drained fluid only had a very light orange color.

12. Close the valve. Wipe off any coolant under the car. And add 4.5 quarts of Dexcool to the reservoir. The coolant capacity is 11.3 quarts and GM recommends a 60/40 water to coolant ratio. I was only able to find gallon jugs of Dexcool so I have 3.5 quarts left over. It didn't all fit until I let it sit about 5 minutes. Top off with distilled water. Wait 5 minutes and fill to the correct level with more distilled water.

13. Install the reservoir cap. Run the engine again until operating temperature is reached. Let cool and top off fluid with more distilled water.

I still need to take the car for a good ride and check the level again. It was very easy but a little time consuming. Also make sure to dispose of the old coolant properly. I hope this makes things a little easier for someone. The coolant is supposed to be changed at 5 years (there is also a mileage limit which would require earlier replacement) so the 2014's are due.

Very nice write-up. It gave me the confidence to proceed with the flush of my 2014 Stingray. Only 14000 miles, but it is 5 years since purchased.

I filled with distilled water and drained 6 times for clear water to come out of the last drain.

I felt setting the heater temperature to "Hi" the first and every time I ran the engine would make certain the flushes flowed through the heater core unrestrained. I am not certain how the heater works in the Corvette making this precaution of questionable value.

I also lifted the overflow reservoir enough to make a mark on the side at the level of the minimum cold coolant level. This is one thing that is irritating and happens in a lot of cars. The mark on the side of the reservoir is almost always in a position that it cannot be seen. This is one attention to detail that would be so simple for the designers of the components but they do not anticipate how difficult they make maintenance by molding the markings into the reservoir in a place that cannot be seen. My reservoir now has a line drawn by a black Sharpie that can be easily seen on the side visible when the hood is open.