# My total fix for coolant smell



## obermd (Mar 3, 2012)

All you did was route the coolant leak elsewhere. In your case the best fix, which eliminates the leak, is to replace the bottom O-ring in the surge cap with a better o-ring. https://www.cruzetalk.com/threads/fix-coolant-odors-coolant-loss-from-reservoir.110049/ has a full description of the problem and solutions that will eliminate the leak itself.


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## 375802 (Jul 9, 2019)

obermd said:


> All you did was route the coolant leak elsewhere. In your case the best fix, which eliminates the leak, is to replace the bottom O-ring in the surge cap with a better o-ring. https://www.cruzetalk.com/threads/fix-coolant-odors-coolant-loss-from-reservoir.110049/ has a full description of the problem and solutions that will eliminate the leak itself.


Are you kidding me with that comment? It was the VENT! The VENT was releasing the smell not coolant. No leaks! What is your issue? Car never leaked it is the VENT>> OMG


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## 375802 (Jul 9, 2019)

obermd said:


> All you did was route the coolant leak elsewhere. In your case the best fix, which eliminates the leak, is to replace the bottom O-ring in the surge cap with a better o-ring. https://www.cruzetalk.com/threads/fix-coolant-odors-coolant-loss-from-reservoir.110049/ has a full description of the problem and solutions that will eliminate the leak itself.


BTW where in the post did I mention a leak?


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## plano-doug (Jul 1, 2015)

CruzeGuy14 said:


> Are you kidding me with that comment? It was the VENT! The VENT was releasing the smell not coolant. No leaks! What is your issue? Car never leaked it is the VENT>> OMG



Something is coming out, whether it's liquid or gas, something is coming out, or you wouldn't smell it.

Re-routing the hose makes it less likely for the odor get into the cab, but doesn't stop whatever is coming out.

When I read your post, I thought it was clever what you had done, but that the cap probably needed a new o-ring.

Doug

.


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## 375802 (Jul 9, 2019)

plano-doug said:


> Something is coming out, whether it's liquid or gas, something is coming out, or you wouldn't smell it.
> 
> Re-routing the hose makes it less likely for the odor get into the cab, but doesn't stop whatever is coming out.
> 
> ...


O ring is not leaking. It was venting out of the vent. There is a foam seal that Chevy installed under the cowl gasket to help the vent issue. Mine came unstuck. Now mine "Vents" to the fenderwell. No leak. No Vent issue.


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## obermd (Mar 3, 2012)

CruzeGuy14 said:


> Are you kidding me with that comment? It was the VENT! The VENT was releasing the smell not coolant. No leaks! What is your issue? Car never leaked it is the VENT>> OMG


If you can smell coolant you have a leak. Engine coolant systems are supposed to be sealed, so there should never be a coolant smell. The "fix" you came up with is exactly the same as PI-0740. This doesn't fix the problem but simply reroutes the coolant vapors down to the wheel well area so it won't get sucked into the cabin air intake, which sits about 12 inches behind the surge tank.

My 2012 ECO MT had the same problem you're having. I worked with several other really smart people here and put together the thread at https://www.cruzetalk.com/threads/cruze-cabin-odors-sources-and-resolution-summary.13717/, which at the time covered all "non-leak" sources of coolant odors as well as how to diagnose and fix them. A few new leak sources have been discovered in the intervening years but that thread is still a good place to start.


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## obermd (Mar 3, 2012)

CruzeGuy14 said:


> O ring is not leaking. It was venting out of the vent. There is a foam seal that Chevy installed under the cowl gasket to help the vent issue. Mine came unstuck. Now mine "Vents" to the fenderwell. No leak. No Vent issue.


Have you actually looked at the underside of the cap? I suspect there is coolant between the two O-rings, which only occurs when the lower o-ring isn't holding the 20 PSI printed on the cap.


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## snowwy66 (Nov 5, 2017)

They're all right. You know. 

You wouldn't have a smell if it wasn't venting. Or leaking. 

I"m sure you didn't have that smell when the car was brand new. If you bought it brand new. 

When I have a problem. I fix. Not hide it.


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## ChevyGuy (Dec 13, 2014)

What's the venting path on this setup? I assume things are supposed to vent if it exceeds the cap's rating.


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## obermd (Mar 3, 2012)

ChevyGuy said:


> What's the venting path on this setup? I assume things are supposed to vent if it exceeds the cap's rating.


It's been a while since I had the chance to look, but my memory is that the coolant vapor pressure presses against the spring loaded plate in the top of the cap. When the pressure exceeds 20 PSI the plate is pushed up and the venting goes out the top of the cap and to the side channel. When the lower o-ring fails to hold pressure the vapor can bypass the pressure plate and seep out through the threads between the cap and tank. As the vapor pressure is released the coolant re-liquifies and drains down into the channel again.

This interface happens to be the only place in the Cruze's coolant system that cannot be pressure tested. Pressure testing is done with the cap off and the pressure gauge connected where the cap goes. The cap test screws into the cap.


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## jblackburn (Apr 14, 2012)

You shouldn't smell anything from the vent under normal circumstances. It is there to act as a vent when the cap/O-ring hits its limit.

I had to replace my whole surge tank/cap because the plastic was deformed slightly around the seam - you could actually see it bubbling out of the vent slightly when the car was hot. New cap didn't fix the issue.

Never a coolant smell again until the water pump dumped coolant all over my driveway.


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## Blasirl (Mar 31, 2015)

I saw this when you first posted it and went and looked at my car. For some reason I figured you had a different style coolant tank. Now that I have read all these comments, and relooked at the picture, how did you connect the hose anyways? I have not yet been able to find the actual PI.

PI-0740 additional instructions


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## Stingray1974 (Mar 14, 2012)

375802 said:


> I went to Autozone, got some windsheild washer hose, removed the little plastic vent cover (just pop's off) used 2 part epoxy and routed the house into the fender well. No more coolant smell  *UPDATE: The admin Obermd trashed my post! He obviously didn't read it. My car has never leaked coolant, the Cruze is knows for the vent to vent smell out of the tank into the intake. There are several mentions of this. This is my fix for the vent smell not a leak as this guy mentioned. Anyway this worked for me, didn't route a leak, I routed the vent of the tank..take care*
> View attachment 283078


I had a 2013 eco and GM's first bulletin/fix was to route the overflow to the bottom. Then they sealed the cowl and fender, then the water pump, then replaced the tank, then they replaced the heater core and the problem only got worse. I monitored the engine and every time I had odor the engine was above 245 Dec F. 
They traded me for a new 2015 that said the problem was fixed. I had the same problem so I did not let them make it worse. I checked the engine program and the coolant fan command goes to 100% too late and lets the engine get hot and vent. This causes the odor and coolant loss over time. It probably weakens the system to cause actual leaks. I asked GM if they would change the program-NO. Well then I asked if I could change it and the district manager said yes. I changed the coolant profile for the different torque modes and never had another high temperature or venting problem.
This is the same program for all and is the root cause of the coolant issue. You can try to bandaid it but it will come back when the engine gets hot. This is even worse in the winter because of the way the program works. 
Now I have a new GM turbo and the coolant program was changed like the changes I made. The engine does not get hot and there is no coolant odor or leak. If you look at the programs you will see the differences and how the Crude waits till it is way over the 221 Deg temp command before the fan is set to 100%.


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## snowwy66 (Nov 5, 2017)

That's how the first cruze is designed. 

221* thermostat. 230* fan kick on.

Stupid idea. But who are we to argue with engineers. I have no idea why it's made to run 30* hotter then normal.

I bet that idea cost gm a ton of money in warranty


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## Stingray1974 (Mar 14, 2012)

375802 said:


> Are you kidding me with that comment? It was the VENT! The VENT was releasing the smell not coolant. No leaks! What is your issue? Car never leaked it is the VENT>> OMG


Venting gas is a leak of coolant and should only happen when the car is overheating. It does overheat because the program allows that. You can't see this because the temp gauge does not move up even when the temperature is 250 Deg. Monitor your engine temp with a Torque program and ODBII Bluetooth and you will see it go over the 221 Deg program value. See my comment below I had 2 new Cruze eco with the same problem. I modified the program on the last one and never had another issue in over 80,000 miles.


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## Stingray1974 (Mar 14, 2012)

snowwy66 said:


> That's how the first cruze is designed.
> 
> 221* thermostat. 230* fan kick on.
> 
> ...


If you look at the system and program you can see the thermostat is electronic and the program controls variable fan speed. This is not like the old cars with simple mechanical thermostat and fan clutch or on off only. It appears the engineers made a mistake on the cruze and GM probably didn't want to spend the money on recalls or EPA recertification if they made the change. It only gets hot in certain torque modes and vents a little each time. I monitored many thousand miles and checked the program against many other new GMs and it is different and causes venting. After the change on my Cruze I never had the slightest odor or coolant loss. Before lost 4-8oz at every oil change.


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## Stingray1974 (Mar 14, 2012)

Stingray1974 said:


> If you look at the system and program you can see the thermostat is electronic and the program controls variable fan speed. This is not like the old cars with simple mechanical thermostat and fan clutch or on off only. It appears the engineers made a mistake on the cruze and GM probably didn't want to spend the money on recalls or EPA recertification if they made the change. It only gets hot in certain torque modes and vents a little each time. I monitored many thousand miles and checked the program against many other new GMs and it is different and causes venting. After the change on my Cruze I never had the slightest odor or coolant loss. Before lost 4-8oz at every oil change.


There is no 230 Deg kick on. In the original program 221 deg mode the fan speed starts at only 15% at 221 deg F and doesn't go to 100% until 244 Deg F. This allows the engine to go way over the desired 221 Dec F.


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## snowwy66 (Nov 5, 2017)

Don't know what to tell you.

Thermostat is designed for 221*
Fan switch is designed for 230*

Normal is 190 and roughly 205 to 212.

We all know it's a hot motor. What we don't know is why.


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## jblackburn (Apr 14, 2012)

Stingray1974 said:


> There is no 230 Deg kick on. In the original program 221 deg mode the fan speed starts at only 15% at 221 deg F and doesn't go to 100% until 244 Deg F. This allows the engine to go way over the desired 221 Dec F.


That makes sense...high rad fan speed shouldn't be needed unless absolutely necessary; it's very loud and draws a ton of power. Low/med speed is more than enough airflow to cool off the huge radiator for a tiny engine at 220-230 coolant temps.

One pretty common issue with these cars is that the lower speeds of the fan/resistor pack do burn out.


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## ChevyGuy (Dec 13, 2014)

Stingray1974 said:


> There is no 230 Deg kick on. In the original program 221 deg mode the fan speed starts at only 15% at 221 deg F and doesn't go to 100% until 244 Deg F. This allows the engine to go way over the desired 221 Dec F.


However, I wouldn't expect any significant venting until you reached the boiling point of the coolant. Which according to this document is 265F at 15 PSI.


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