Strange coolant behavior

CamaroChriSS · 08-22-2022, 09:08 AM

I recently replaced the fan in my car, and in doing so lost a lot of coolant so I topped it off and thought I purged the system of air by letting it run for 10 to 15 minutes with the cap off. I had both reservoirs topped off at the cold line, but then after driving and sitting overnight, the upper reservoir is full and the lower reservoir has dipped. I would assume it would settle back at the cold line on the upper reservoir, but it’s definitely not doing that. Is the system overfilled? Or is that an indicator of air in the system? Something else?

CamaroChriSS · 08-22-2022, 09:12 AM

For clarity, this picture is from after the car sat overnight and was completely cool

SSDan · 08-22-2022, 09:20 AM

The upper reservoir should be always full (there is no cold line) and the lower tank is the overflow tank and needs to be kept at the cold line. I know that sounds backwards and most would thing the lower tank is the reservoir and the upper tank would be the overflow. But not for our cars.

You are not overfilled. Bring the botton tank back up to the cold line and then monitor.

CamaroChriSS · 08-22-2022, 09:26 AM

Thanks! I know our systems are a little bit different than standard, so I figured I would ask here before doing anything stupid like taking coolant out.

ctrlz · 08-22-2022, 09:47 AM

Bring the lower reservoir up to the fill line and see what happens. You have a few small air bubbles in the upper reservoir. I bet they go away after a few driving cycles. Don't touch the cap on the upper tank, that will only introduce air.

Trochoidal · 08-22-2022, 04:00 PM

I’ve had the coolant out of my car twice and both times the lower reservoir did the same thing as what you’ve described. IMO, this is normal and you may have to top that lower tank off a second time after it sits overnight.

lt4camaro · 08-22-2022, 08:55 PM

That overflow tank cold reading (after it sits overnite) will always be lower than when you look at the level right after a good drive. That is when the reading will always be higher. You do not have to keep it right at the cold level line when cold, it can be a inch lower no problem. The colder the night, the slightly lower the coolant level will be. As long as you can see about a inch of coolant in the tank on the coldest morning after sitting all night you are good.

CamaroChriSS · 08-23-2022, 12:41 PM

Appreciate it, everyone! Coolant is so simple in theory, but one stupid mistake... new engine.

08-22-2022, 09:08 AM	#1
CamaroChriSS Drives: 16 1SS M6 Black -previous 00 Z28 M6 Join Date: Oct 2018 Location: DC Posts: 255	Strange coolant behavior I recently replaced the fan in my car, and in doing so lost a lot of coolant so I topped it off and thought I purged the system of air by letting it run for 10 to 15 minutes with the cap off. I had both reservoirs topped off at the cold line, but then after driving and sitting overnight, the upper reservoir is full and the lower reservoir has dipped. I would assume it would settle back at the cold line on the upper reservoir, but it’s definitely not doing that. Is the system overfilled? Or is that an indicator of air in the system? Something else? Attached Images

08-22-2022, 09:20 AM	#3
SSDan Drives: 2016 1SS 6MT NPP Join Date: Feb 2010 Location: Lake Murray, SC Posts: 2,245 View My Garage	The upper reservoir should be always full (there is no cold line) and the lower tank is the overflow tank and needs to be kept at the cold line. I know that sounds backwards and most would thing the lower tank is the reservoir and the upper tank would be the overflow. But not for our cars. You are not overfilled. Bring the botton tank back up to the cold line and then monitor. __________________ 2016 Camaro 1SS Hyper Blue 6MT NPP 2010 Camaro 2SS Cam/Headers/CAI/3.91 gears 476 rwhp/440 rwtq (sold)

08-22-2022, 04:00 PM	#6
Trochoidal Drives: 2017 Camaro 2SS A8 Join Date: May 2019 Location: USA Posts: 1,656	I’ve had the coolant out of my car twice and both times the lower reservoir did the same thing as what you’ve described. IMO, this is normal and you may have to top that lower tank off a second time after it sits overnight. __________________ Roto-Fab w/sound tube delete, Katech ported TB, Pray IM, Velossa, DD side markers, DSX FF, UPR Catch can, Halo brace, My custom vent gauge pod Originally Posted by arpad_m - “Aww, yet another oil thread with almost the same question in the OP“

08-22-2022, 09:12 AM	#2
CamaroChriSS Drives: 16 1SS M6 Black -previous 00 Z28 M6 Join Date: Oct 2018 Location: DC Posts: 255	For clarity, this picture is from after the car sat overnight and was completely cool

08-22-2022, 09:26 AM	#4
CamaroChriSS Drives: 16 1SS M6 Black -previous 00 Z28 M6 Join Date: Oct 2018 Location: DC Posts: 255	Thanks! I know our systems are a little bit different than standard, so I figured I would ask here before doing anything stupid like taking coolant out.

08-22-2022, 09:47 AM	#5
ctrlz Drives: 2017 2SS, 50th pkg, M6, MRC, NPP Join Date: Jan 2016 Location: Ocean City, NJ Posts: 3,190	Bring the lower reservoir up to the fill line and see what happens. You have a few small air bubbles in the upper reservoir. I bet they go away after a few driving cycles. Don't touch the cap on the upper tank, that will only introduce air.

08-22-2022, 08:55 PM	#7
lt4camaro Drives: 2021 LT1 10 speed auto Join Date: May 2013 Location: Connecticut Posts: 2,343	That overflow tank cold reading (after it sits overnite) will always be lower than when you look at the level right after a good drive. That is when the reading will always be higher. You do not have to keep it right at the cold level line when cold, it can be a inch lower no problem. The colder the night, the slightly lower the coolant level will be. As long as you can see about a inch of coolant in the tank on the coldest morning after sitting all night you are good.

08-23-2022, 12:41 PM	#8
CamaroChriSS Drives: 16 1SS M6 Black -previous 00 Z28 M6 Join Date: Oct 2018 Location: DC Posts: 255	Appreciate it, everyone! Coolant is so simple in theory, but one stupid mistake... new engine.

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