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Fan still running for a few minutes after truck turned off.

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70K views 27 replies 18 participants last post by  gherbert  
#1 ·
I drove my truck today 2019 colorado v6. It was about 50 degrees (F) outside. When I got home the fan stayed on even when the key was out I also noticed the temp gauge stayed at 160 the whole drive (basically didn't move). The fan noise is coming form the front end of the truck. Any ideas whats up with this and what I'd have to do to fix it?

Thanks. First time it's ever done that.
 
#2 ·
It's fairly common for the fan to continue to run after the engine is turned off so it continues to draw air through the radiator and over the engine. I wouldn't worry about it unless it runs for hours.

Dash temperature gauges aren't particularly accurate for more than, "Oh crap, it's overheating!" or "It's not warmed up yet"
 
#4 ·
Its typically done so that after a long drive, it can cool the block down, because its still quite hot, so just stopping the coolant flow or stopping the fans tend to cause other issues. Ive heard of the block cracking, but that is super rare at worst. I know this is a GM vehicle here, but when I worked for Audi, the cars had after run coolant pumps to keep the flow moving for a few minutes after shut down. (ironically some of them would catastrophically fail and light the car on fire....there are several recalls for that lol)
 
owns 2016 Chevy Colorado Z71
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#5 · (Edited)
I can't find any documentation that the fan is supposed to run after shut down. My guess is a bad thermostat based on some search results I saw here.

EDIT I found a thread where a poster stated if the coolant temp is 225 at engine shutdown, the system is programmed to run the fan for 300 seconds. Any longer and there is a temperature sensor or thermostat issue.

A bad sensor or thermostat makes sense to me as your issue was on a 50 degree day and the engine should not have been warm if everything was as it should be.
 
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#6 ·
From pg. 258 of the 2019 Owners Manual:
The electric engine cooling fans
may run after the engine has been
turned. off. This is normal and no
service is required.
 
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#7 · (Edited)
I hate to be the Debbie downer here but.....It is NOT NORMAL for it to run at 160, something is wrong, most likely the coolant temp sensor. The truck is running the fan because it knows it should be warmed up and it's showing it isn't, so it is running the fan just incase it's hot. Take it in...
(it very well could be the thermostat stuck open too)
 
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#9 · (Edited)
Having lost three, THREE! great vehicles to cooling issues, I feel compelled to contribute what I can here.

First off, strange things happen in the cold. If your coolant system is going to blow, It will when its cold and while your on your way to see family on holiday.

The cold affects a few things. Your system is designed to run hot and cool itself AFTER it has gotten hot (thermostat opens, etc). When that heat up cycle is interrupted because its cold outside, many engines don't heat up enough to cycle the coolant.

Another thing that happens is old and soft rubber hoses will leak or blow altogether due to being over pressured while being too hard to expand. Any weakness in the hose, or a hose that is softer than the others will leak or rupture. This is why when changing coolant hoses, change all at the same time.

Another thing is filling. There may be air pockets trapped in the system that will fool the temp sensors. You can't rely on the sensors as they will show normal (most are just 3 position dials) when all else is boiling. By the time these sensors show overheat, the engine is toast.

So, (another thing), don't expect your vehicle to run perfectly in the cold but this is a time to be extra vigilant on watching your system closely. There are a few things you can do.
(1) Watch the coolant level more than normal. Don't be alarmed if you see drastic changes in coolant level in the cold. The system will purge and draw more from the reserve because the cool-down will suck in more. Add coolant when it gets below the minimum line, but leave room for expansion.

(2) Get the engine hot. As much as possible, get it up to running temps. Keep the cabin heater on warm to enable flow through the core.

(3) Purge air. Many of these trucks are not completely filled from the factory and don't fully purge unless its forced. Occasionally gunning the motor will purge air out of trapped pockets. Parking at angles will promote air pockets to float up to the Reservoir, which is not located at the front of the engine bay as the car god intended, but stupidly at the back of the engine bay. So, as these closed systems flow so slowly, park tilted up to promote air flow to the front, then park down to flow to the reservoir. Either way, hammer down occasionally to flush out that air.

(4) The ugly part, because it costs $$. Replace stuff b4 they break. Rubber parts get soft, loose their elastomers and plasticizers. In the cold, they will split open.
"Finally, the polymers and molecules in rubber prefer to be “warmed” up to have maximum flexibility and resilience, so stretching rubber out in cold weather can sometimes be dangerous. When the temperature is low, the molecules don’t move past one another as readily, and can make rubber brittle and prone to snapping. " Why Do Rubber Bands Lose Their Elasticity? » Science ABC
When your radiator hoses start to balloon when hot, start looking to replace them. It can be the easiest job with this tool:
Image

And for God's sake, NEVER use these:
Image

That explanation is another paragraph I don't want to write.

So, watch your coolant level. Be prepared to fill coolant at any time with correct coolant. Don't totally trust the temp gage. Run with the heater core flowing. Where you park, notice if there is a puddle there before you pull in so you will know if a puddle is yours when you leave.
 
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#10 ·
Having lost three, THREE! great vehicles to cooling issues, I feel compelled to contribute what I can here.

First off, strange things happen in the cold. If your coolant system is going to blow, It will when its cold and while your on your way to see family on holiday.

The cold affects a few things. Your system is designed to run hot and cool itself AFTER it has gotten hot (thermostat opens, etc). When that heat up cycle is interrupted because its cold outside, many engines don't heat up enough to cycle the coolant.

Another thing that happens is old and soft hoses rubber hoses will leak or blow altogether due to being over pressured while being too hard to expand. Any weakness in the hose, or a hose that is softer than the others , will leak or rupture, This is why when changing coolant hoses, change all at the same time.

Another thing is filling. There may be air pockets trapped in the system that will fool the temp sensors. You can't rely on these as they will show normal (most are just 3 position dials) when all else is boiling. By the time these sensors show overheat, the engine is toast.

So, (another thing), don't expect your vehicle to run perfectly in the cold but this is a time to be extra vigilant on watching your system closely. There are a few things you can do.
(1) Watch the coolant level more than normal. Don't be alarmed if you see drastic changes in coolant level in the cold. The system will purge and draw more from the reserve because the cool-down will suck in more. Add when it gets below the minimum line, but leave room foe expansion.

(2) Get the engine hot. As much as possible, get it up to running temps. Keep the cabin heater on warm to enable flow through the core.

(3) Purge air. Many of these trucks are not completely filled from the factory and don't fully purge unless its forced. Occasionally gunning the motor will purge air out of trapped pockets. Parking at angles will promote air pockets to float up to the Reservoir, which is nor located at the front of the engine bay as the car god intended, but stupidly at the back of the engine bay. So, as these closed systems flow so slowly, park tilted up to promote air flow to the front, then park down to flow to the reservoir. Either way, hammer down occasionally to flush out that air.

(4) The ugly part, because it costs $$. Replace stuff b4 they break. Rubber parts get soft, loose their elastomers and plasticizers. In the cold, they will split open.
"Finally, the polymers and molecules in rubber prefer to be “warmed” up to have maximum flexibility and resilience, so stretching rubber out in cold weather can sometimes be dangerous. When the temperature is low, the molecules don’t move past one another as readily, and can make rubber brittle and prone to snapping. " Why Do Rubber Bands Lose Their Elasticity? » Science ABC
When your radiator hoses start to balloon when hot, start looking to replace them. It can be the easiest job with this tool:
View attachment 417751
And for God's sake, NEVER use these:
View attachment 417752
That explanation is another paragraph I don't want to write.

So, watch your coolant level. Be prepared to fill coolant at any time with correct coolant. Don't totally trust the temp gage. Run with the heater core flowing. Where you park, notice if there is a puddle there before you pull in so you will know if a puddle is yours when you leave.
Thank you for the information! I’m taking my Canyon in to the dealership after work. Hopefully it’s a covered under the extended warranty. It’s funny that you mentioned the failure when it’s cold. I took a trip to Oregon and the truck was super happy driving in the cold except for the rough patch where I had to put the chains on.
 
#12 ·
My 2016 did that, but I was loosing small amounts of coolant. The reservoir would only be down a inch or two but the truck would start to over heat. Took two repair shops before the leak was detected in a couple of hoses near the back end of the engine?? No third party part so they had to get it from the dealer, but since replacing the leaky hose I've had no loss of fluid and no fan running after shutdown.
FYI I live in Central Florida so 60 degrees is freezing to us. Truck sits outside in the heat all the time.
 
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#18 ·
I see this almost everyday on the Facebook Colorado/ZR2 pages. Lot of bad sensors are starting to show up.
We have 2 coolant sensors in the V6's, 1 on the front of the block/heads and 1 at the bottom side of the radiator. Not 100% sure but the block/heads is for the ECU and Radiator is for the temp gauge. Anyone know for sure?
 
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#16 ·
It's fairly common for the fan to continue to run after the engine is turned off so it continues to draw air through the radiator and over the engine. I wouldn't worry about it unless it runs for hours.

Dash temperature gauges aren't particularly accurate for more than, "Oh crap, it's overheating!" or "It's not warmed up yet"
I know this is a old post but it is NOT common for a fan to constantly run when engine is off. Drove my 2018 z71 V6 15 miles is 50 degree weather when I got to my destination the front fan was running and temperature gauge was at 160
I did make back it home then check engine light came on. Dealership tomorrow hope it can make the 8 mile drive without any extended damage.
This my second Colorado and damn sure my last.
Blew engine on the a 2005 due to cooling problems.
Bottom line it is not common and will only create more damage. My advice take it in before it’s to late.
Will Update soon
 
#17 ·
I know this is a old post but it is NOT common for a fan to constantly run when engine is off. Drove my 2018 z71 V6 15 miles is 50 degree weather when I got to my destination the front fan was running and temperature gauge was at 160
I did make back it home then check engine light came on. Dealership tomorrow hope it can make the 8 mile drive without any extended damage.
This my second Colorado and damn sure my last.
Blew engine on the a 2005 due to cooling problems.
Bottom line it is not common and will only create more damage. My advice take it in before it’s to late.
Will Update soon
Most likely the thermostat is stuck open.
 
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#20 ·
I had the same exact issue (although on a colder day this past February). Dealer read the code and replaced the thermostat and engine temperature sensor - at my expense. This was a $760 repair. Way out-of-line, and I wrote them same during my survey response. They estimated 3 hours of labor in addition to the 1 hour charge to diagnose the problem. My 2018 4x4 CC SB V6 LT has 118,000 and I plan to go at least until 200,000 so keeping the truck maintained is a priority. But, I will not return to that shop for any more repairs on this vehicle. Jimmy B
 
#26 ·
Member you Replied to is No Longer Active/Here:
NorthwestWanderer
Registered · From Western Washington
Joined Dec 16, 2018
Last seen Feb 13, 2022

But, what the Former Member Described is due to the Thermostat being Stuck Open:
The Tempature Gauge stays at 160
Fans Run for about 5 Minutes after vehicle is off
It is a Safety Mode for the Truck
Treating it as Possible Overheating...
Treat for Worse Case Scenario

I just had to replace my Thermosat on Sunday due to the same exact thing
 
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#27 ·
I am having the running fans too, at 256k.
$300 later, stealer says the coolant temp sensor is faulty. Makes sense, the fans will run in case there is an overheating condition.

Diagnostics also showed a thermostat latency. So its Tstat and sensor time. I have all the parts and know my way around the plenum having already done the sparkies.
Its surprising to me such a high quality Tstat would have this issue.
Image


Another interesting thing is my voltage has shot up to 15V during this failure. Is the Alternator over charging to compensate for the fans?
 
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#28 ·
Well I only had to change the Thermostat and everything went back to normal
But, at 256K it not like the Temp Sensor owed you anything
 
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