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Gonna speculate a bit......new to the forum but cars is cars and I've got 48 years under my belt.

Surge tanks are not a new technology......they take the place of the top tank that is part of any old top to bottom flow radiator.
Now, before closed cooling systems, using a non- pressurized overflow bottle, the coolant was generally kept in the 1" below the filler neck range.
The radiator caps were in the 14 to 16 lb. range.
If the coolant was in the 1" below the neck range, there was enouph airspace in the tank to approach 14 to 16 psi and the cap would not release any pressure.
As an aside, for those who don't know, a 50/50 mix of anti-freeze and water (coolant) under pressure has a boiling point of around 235 degrees.
This is necessary because there are areas within the cooling system that operate in excess of 212 degrees and prevents gas bubbles within the passages.

In years subsequent, a coolant overflow bottle along with a positive/negative sealed radiator cap was employed so that the radiator would always be 100% filled, increasing its cooling capacity without changing its dimensions.
Since a liquid cannot be compressed, as soon as the coolant began to expand with engine operation, at 14 to 16 psi, the coolant would be admitted into the overflow bottle.
Once shut off, the coolant in the radiator would contract and, through the negatively sealed cap, would pull coolant back out of the bottle into the radiator, maintaining a 100% fill.

Some time in the late 50's or early 60's Chevrolet intoduced the Corvette with a wider, but shorter radiator so the hoodline could be lowered.
This is called a crossflow (left tank to right tank) radiator, but because of the small airspace volume available, and the fact this radiator had to be 100% filled to adequitly to keep from overheating, a pressurized surge tank was utilized. The 16lb radiator cap was attached to the tank, the same as the 20 psi cap is attached to the cruze.

So, the function of the surge tank, be it in the Corvette, or our Cruze, is the same.......it takes the place, and provides the space for expansion.
In the case of the Corvette, the coolant had to be no closer than two inches below the fill cap on the tank.
If you took it too high, the airspace was inadequite and it would rise beyond 16 psi......puking the coolant out of a overflow hose attached to the radiator cap adaptor on the side and leading to the ground.

Sound familiar?

I contend that the full cold marker on the surge tank is being disregarded by either the factory or the dealer or whomever is getting under the hood.

Full cold means the level of the coolant in the surge tank after sitting overnight.
I wish (nuts, I don't even know if) there was not a 'Full Hot' marker......this because few people understand it has been determined that if it ever exceeds that line, the cap will be enduring 20 psi and will be venting.
Add to that, Chevrolet chose A. To not install a vent line to carry the steam away from the passenger compartment and B. to place that vent point in front of a fresh cabin air inlet.

But, this just proves that engineers, just like doctors, can get their degree with a D-........The degree says they are a Doctor/Lawer/Engineer.

This was/is D- class engineering.

IMO.....At your first opportunity, after the vehicle has been left overnight.(10 hrs) remove the cap and using something like a turkey baster, suck the coolant down to the tip of the arrow pointing at the 3/4" (I think) hose on the passenger side of the tank.
Throughly rinse the radiator cap in fresh water and re-assemble.

To those who have had a coolant smell.......it won't disappear overnight.
That coolant steam that was pulled into the air inlet has condensed inside the cold walled heater box.
Coolant evaporates, but really slowly........don't be surprised if you pick up the scent for a week or two......but it will go away.

Good maintenance means you check your oil/washer solvent/COOLANT LEVEL once a week.....
If all is well, meaning the entire cooling system is not compromised (leaking) you should see your cold coolant level will hardly ever change, summer or winter.
As long as there is any visible coolant in the surge tank, rest assured the radiator is filled to the brim.


Hope that was worth something,
Rob



PS jblackburn and Bohdan have observed what I am trying to define and.............
To those that find the bottle overfilled.......once you drop the level, the oder will take several days to dissapate.
Those vapors have condensed inside the heater case and will take about a week to finally evaporate off.......aaaaaand, you may have to replace the cabin filter as well as the paper pleats will tend to hold coolant for ages.
 

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UpstateNYBill,

You can see and likely experienced what I'm getting at......I'd bet the dealer added coolant during pre-delivery and the tank had to keep venting itself down to the level it is now at.

Good observation.

Rob
 

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Lets not freak folks out.

Glycol, injested, is a poison that will destroy kidneys.

Glycol fumes, in the concentration that would exist in the cabin are just that, fumes.
I imagine if the concentration could reach 50% it could be sickening......like I wanna puke, but I would hope one would've bailed out of the car at that point.

Unpleasant yes, life shortening, doubtful.

Rob
 

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obermd?

You successfully have my head spinning here.......I've read your response several times aaaaaaand I believe something got lost in translation regarding the surge tank modification.

First, the surge tank relief port was not drilled...it already exists.
The modification is simply removing the liquid coolant guide (that plastic thingy that goes from the top of the tank and leads down the side.
This exposes the relief port.
A hose is pushed onto the port and the tape is to secure the line across the tank in the hopes of preventing vibration from pulling it back off the port.
The function and pressure holding capability of the surge tank has not been altered in any way.

I said somewhere else, this is a situation where engineering can't see the forest for the trees.
The outgassing from the tank vent is occuring because tank pressure is rising past 20 psi, the pressure caps limit.

The tank is overpressuring because the coolant is being put at too high a level when at ambient temperature and because the airspace has become so small, due to the coolant displacing the air in the tank, it quickly exceeds the 20 psi limit.

When the cap reaches its design limit it releases the tank pressure back down to 20 psi and reseats.
This release, reseat routine will go on till the coolant expands no further at operating temperature......as as we all know, it exhales just ahead of the HVAC air intake.

The installation of the hose was, I believe, in the hopes of redirecting the vapor.
Trouble is, it isn't supposed to exceed 20 psi in the first place so the concern is still not addressed.

And, it never will be till G.M. tells everyone from the assembly line to the mechanics doing the pre-deliverys to the consumers what the COLD level (ambient) of the coolant in the surge tank should be.......it is not even stated in the owners manual.....just says keep it at the correct level.

The only marker on the surge tank is a arrow that says 'FULL HOT'......well, thats just great but useless....unless you really want to remove a cap, under pressure, with scalding coolant that will blow out the moment the pressure drops.

I found by having the cold, first thing in the morning cold, coolant level 1/2" above the lower tank inlet hose, in line with the top of the verticle cast in the plastic line that is centered over that lower hose nipple, the surge tank pressure rises to 14psi and stays there regardless of the length of my trip.

I proved this by operating the vehicle with a pressure tester installed in place of the cap and bunge corded away from moving parts.

I still contend.....the majority of these concerns are a result of inadvertent overfilling of the surge tank due to G.M.s inability to provide a 'FULL COLD' marker and poor/imprecise info in the owners manual.

The heater cores, water pumps, heater boxes may be contributing to the concern but I am only interested in trying to keep those of us with sound cooling/heating systems from having a problem due to coolant level.

Rob
 

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Regarding the pressure relief cap (radiator/surge tank cap).

When cold, remove the cap.

Note the 'O' ring at the lower section of the cap and visualize its position when installed in the surge tank.
The 'O' ring seals the fill hole below the level of the vent hole.
When surge tank pressure exceeds 20psi, the internal valving in the cap opens and vents above the 'O' ring into the area of the fill neck between the 'O' ring and the very top of the surge tank fill hole.
This section is about 1/2" deep.
When the cap is forced to vent, the overpressure is released into this chamber and exits out the port that we see on the left side of the tank.

The point that I keep trying to make is, by misinterpeting the coolant level (cold, ambient temperature) and in so doing, overfilling it, we are forcing the system to vent.......it is working correctly.
Pressure much beyond 20psi will burst hoses and turn the surge tank into a balloon.......not what was intended.

By using the level I have mentioned as our 'COLD' starting point we are succeeding in:

1. Starting the vehicle cold knowing that the entire cooling system is full.....remember, the tank is only a place for coolant to go as it expands.
2. Assuring ourselves that the only time we smell coolant is because the cap or some other element of the cooling system has been compromised and is calling for attention.

In truth, rather simple and a example of what can happen when a concern gets 'overcooked' with thought and misunderstanding without stepping back and taking a moment to rethink whats happening here.

All this, for something as simple as overlooking the need for a 'FULL COLD' marker.

Like I said....Can't see the forest for the trees.

Old saying.....but I'm old (er)

Rob

BTW, For purposes of clarification, the Cold level I mention at the lower tank hose corresponds with the SECOND line up from the bottom of the tank viewed from the front of the tank.
 

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As a addentum.

If you have been dealing with this odor for a long time.....like months or longer, you may still smell coolant after dropping the tank level.
You likely will have to replace the cabin air filter (behind the glove box door) because, over time, the fibers of the filter have trapped condensed coolant.
Every time humid air is drawn through the filter it will dampen the dried residue and the odor will return, making you think the problem has not been resolved.

Rob
 

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Blue Angel?
If that is what vauxaul is using as their full point then all the cars over there have stinky heaters too IMO.
You just proved to me that this is a engineering oversite.

The entire thrust of this conversation is pointing out that there isn't enouph airspace in the tank if the coolant is at that level at cold start.
 

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OK, Regarding the fill point I decided on.
BTW, I'm sure our tanks are the same.

After reading this a several other threads, after purchassing ny Cruze in January (was not a member) I started paying attention to my surge tank.
At time of delivery, it was at the third line up from the bottom and I never had the oder.
I kept an eye on it, checking in the morning and then after my one hour tollway drive to the airport (I have a man cave there known as a 50x50 hanger.
I found the level would rise one full line, up to the fourth line checking upon arrival.
Seems good to me, no residue around the vent deflector.....no worries.

As I continued to read the thread and watched it grow I became more interested......And, using a flashlight (63 yr old eyes, remember) noted the arrow is at the one line below the seam line level.

Thinking now, 'How often does a service facility see a absolutely at ambient temperature cooling system?'
I wonder if these things are simply being overfilled?

So, the next morning, I filled it to the arrow (28f ambient) and installed the pressure tester.
Took a ten mile ride.....long enouph for the gauge to stabilize.
When I got back home I checked the pressure gauge......there it is, 22psi and the level is right at the weld line.
If it had the cap installed it would've vented.

Next morning, I dropped it to the second line down and repeated the road test.
Results were 18psi.......probably OK BUT i like a bit of a buffer.

Following morning, sucked it down to the third line down and repeated......17psi after the ride.

And again, dropped a line and repeated.....14psi........at this point it was clear the airspace in the tank, if filled to the arrow tip, is likely inadequate.

I decided, using past experience, this line, second from the lowest line up will be a safe 'COLD' starting point.
After 10 to 15 minutes driving, it is up to the third line from the bottom........driving to the airport and back, it is still at the third line from the bottom.

I concluded and proved the airspace theory is correct and won't be surprised this summer if it isn't about a half line higher w/ the A/C in operation.

So, my recommendation as far as level could be construed as somewhat arbitrary.......except for the pressure readings....in particular the second one which leaves little room for high ambient air/high operating temperature varience.
Again, I only went through this because of all the odor concerns.....mine was/is fine.

But, had it been filled to the arrow, we know it would've vented.....it was at 22psi.


The function of this tank is that it is a remote radiator tank and just like a radiator tank, it holds coolant and pressure.
In addition it is a by-pass, or surge tank......a place for the cooling system to continually bleed itself of any steam bubbles.
You can see this by leaving the car running and opening the hood.
The 90 degree elbo the small hose is attached to is just clear enouph to watch the flow.
This continually purges the system of any steam bubbles that may develop.

As far as the Vette mentioned.....you did not say what year it is but I will assume it has a surge tank as opposed to a coolant overflow tank.
If it is a surge, notice how much airspace it has when the cooling system is at the 'Full Cold' line.

Way more than the cruze and therefore, not as sensative to a bit of overfill.......also G.M. was kind enouph to provide a 'Full Cold mark.

Just think, had G.M. simply cast a barbed nipple with a hose leading to a low pressure area under the car it would vent to airstream and we wouldn't have anything to fret over.

Rob
 

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I just want to clarify this COLD / HOT debate, does it really matter if I remove coolant from my car to allow more room for expansion? Since this tank is considered an "Overflow" what harm will be done removing small amounts of coolant to show HOT levels below the line? We are talking about 1-4 ounces here, not a lot.


P.S. I understand a line is there for a reason, but sometimes thing are better off "Changed, Modified".


Not a overflow tank.....a surge tank.....two seperate animals and yes you can drop it as low as the second hash mark from the bottom and be fine.....even the third likely will be OK.

Rob
 

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Good insight and very helpful. The question remains - is it the pressure in the surge tank expelling vapors into the cowl intake causing the cabin smell or the HVAC box - or both? Is there a way to troubleshoot before going straight to the HVAC box R/R? Have had the tape/tube/seal job completed. PI job appeared to work to some extent until the coolant temp hit the 200s then the smell came back. Maybe removing some antifreeze to see if the smell dissipates over time?
For starters, look at jblackburns photo above......mine is one line lower first thing in the morning, before startup and is at the line in his photograph after about one hour drive time......although there is nothing other than experience to substanciate this, I believe these levels will prevent the surge tank from overpressurizing and expelling vapors from the relief port.
Although you had the modification performed, I believe, due to the poor hose fit on the nipple, that venting can leak past the junction and be drawn into the HVAC intake.

It is not, nor can it get directly into the HVAC boxes......only drawn into it.
That being said, if your coolant level is at the level I believe will be satisfactory, then the possibilities for oder become a heater core or, as someone stated, the lubricant for the heater door pivots.
That lube thing though is a stretch since the same company makes the heater boxes for all G.M. models and there does not seem to be any complaints registered.

If, however, your level is in the second to third line from the bottom and the oder prevails, I would be inclined to replace the pollen filter.
If your surge tank has been venting, the coolant vapors have accumulated in the fibers of the filter and every time damp/hunid air is drawn through it it will bring the odor back to life.

Rob
 

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Is it possible once the coolant fumes have been released I to the HVAC system the grease would collect particles releasing the smell over longer periods of time just like the air filter? Pretty much once your car has done it once your stuck with it?
I really, really doubt this but I am not in a position to do more than speculate.
I find it virtually impossible that a lubricant, as described in these threads, would 'pick up' a odor......I am quite sure of myself regarding the pollen filter picking up the scent though.

Rob
 

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Robby: I think the experimentation you've done is right on target. One additional question I have is this: If the coolant system gets above 20 psi, does the heater core see that pressure? If so, what is the design point for that piece? Could repeated over pressuring lead to leakage of the heater core? Opps, that was more than one question.
The entire cooling system is exposed to those pressures.
I am confident the heater and radiator could tolerate pressure as high as 50psi.....these are aluminum tubes that coolant runs through and the pressure would be easily handled by those small diameter tubes.
Heater core failures are generally the result of poor seam sealing at the end caps or tube (where the heater hoses attach) junction failures.
The larger hoses suffer much worse than the metal parts at high pressure.

All that being said, if the cap actually allowed pressure to exceed 20psi the most likely first failure would be the tank itself.

Rob
 

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Do the specifications include the specific lubricant or just the thermal and operational characteristics?
Nothing to prove it but I'm reasonably confident the Corporation stipulates the properties of the lubricant, regardless of which supplier builds the assembly......this is true of all vehicle manufacturers.

Rob
 

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Just got my car back from the dealership. My coolant tank cold was at about 1/4 of the way from the second rib to the first rib below the tank weld. 10,000 miles ago it was filled to the first rib below the tank weld while the coolant was hot - it took about 5 minutes to take the cap off to avoid scalding anyone or spraying hot coolant everywhere. There was a very thin coolant/dye line at the tank vent, which I cleaned off. The red line is the Cold Full line from the online GM Maintainance guide. The green line is where my coolant currently sits with an engine temperature of ~70 F.

View attachment 11956 My before startup level is one line below your green line.

My level after about two hours start/shutoff short trips at full operating temp is about where your green line level is drawn....maybe a touch less.

Are you experiencing odor at your current operating level?

Rob
 

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Dropped the coolant to the third mark above the bottom hose and went for a drive. Spent about 2 hours on the road setting the temp control to various positions and running through the different ventilation positions. Results - coolant rose two marks in the surge tank after expanding when hot. Smell just as bad if not worse. My cabin really reeks of coolant. After sharing the results with my wife she informed me:

"I think it is time to consider to get rid of this car."

:iagree:

I think it is time to start looking at other options. Ugh:/
If the level rose two lines you either have a bad cap or the cap to tank seal has failed.
One line rise seems about normal for a sound cooling system.

The dealer should be able to test the cap...if it tests good, needs a bottle.....may be scratched or deformed where the ring seals in it.

Rob
 

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To all readers:
I am aware a lot of you are much younger than I and I often think, because of your youth, or in some cases being unsure of yourself, the dealer service department is not taking you seriously.

And, trust me, it really happens a lot.

You can help yourselves, in particular when given the 'No problem found' business by trying this.
1. Avoid weekend service visits........most dealers only have two or three fully trained mechanics on weekends depending on dealer size. The remaining service people are condidered apprentices and that is a nice term for 'Mechanic in training'
The full line mechanics, in the trades called Journeymen, if working on a weekend are saved for the much larger, higher paying jobs or are finishing left over work.
2. Call the service writer that wrote your service order at 2:00 P.M. No earlier and no later than 2:30.
This is when all vehicles that will be ready for pickup that evening have been reported on by the mechanics.
3. If given a 'No problem found' report tell the writer you wish to speak to the mechanic.
Most, but not all of the time, your request will be granted.
Ask the mechanic why he is unable to duplicate your concern and would he give you a suggestion on how to proceed.
The psycology of speaking directly to the mechanic is to humanize yourself......till the phone call you were a car, now you are a customer with a car.
Human nature is empathy, so when the mechanic grasps the fact you have altered your normal daily routine to get this concern resolved, you will frquently be asked, by that mechanic, some questions regarding reproducing your concern.
If you get this response, you hit a homer and the mechanic may look harder or try a different diagnostic to achieve resolution.
Also, when speaking to the mechanic....there is no sniveling or whining allowed...just the facts, nothing more.
Sniveling, whining, and yelling are the service writers area of grief.
4. Don't keep calling the dealer.....they don't want your car there any more than you don't want your car there but if you keep calling they will make sure your car, repaired or not, will go away (thorn in side theory)

I have worn every hat in the dealer service and parts depts.....now retired I still stay involved.....sick huh?
Anyways, anytime you have a question, feel free to ask.

Rob
 

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Short answer - yes.

Long answer - I've only had a hot coolantish smell when I've used my defroster. I have had a dirty sock smell from day one, even when the coolant level was lower. This was alleviated, but not eliminated, when I replaced the cabin air filter. I also get whifs of burning rubber smell when I run my A/C in city traffic. None of the smells match "cold" DexCool nor do any of these smells exist in the engine bay when I stop and check for them.

I cleaned the coolant residue from the tank vent and will be keeping an eye on the vent. Thanks to you and Blue Angel for educating me - I had a new service adviser retrieve my car for me at the dealership and pull it into the service bay (level floor). When I saw the 1 mm wide coolant residue at the vent he thought my tank had a crack right there. I also opened the cap and did a visual inspection of both the tank lip and the inside of the cap to ensure the cap's pressure seal was intact. It appears to be (no coolant residue on the top of the tank lip or where the cap seats against that lip. GM TAC suggested PI-0740, but I had declined that PI in writing so it wasn't done.
Your odor description is that of a A/C evaporator core growing mold.
The evap. core dehumidifies and in so doing, gets wet like a home evaporator.
This water drips out of the condensate drain.

At shutoff, the blower fan (obviously) shuts off too but now the wet evaporator core (located in the HVAC box alongside the heater core) has no airflow.
So, slooooooowly the water evaporates but leaves behind a real nice buildup that mold just loves to grow in.
Your 'stinky shoe' analogy is the clue.

BTW this is not endemic to the Cruze......this time I can say 'They all do it!' Some sooner than later.
So, what to do......the first is EZ if you have a dealer that knows his stuff.
Have them enable the cooling fan blower after shutdown using the laptop through G.M. Dealerworld.
This will cause the blower motor to run several minutes after shutdown, drying the evap. core.

If after a couple of weeks (patience now) you are still getting a bit of odor and want to persue it (it'll go away eventually, this just speeds it up) the dealer has a product that is sprayed into the heater box, hastening the process.

Rob
 
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