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Cabin odors in the Cruze have been the hardest to solve and longest running problems with our cars. Thanks in a large part to commutertg, (Banks Chevrolet, Concord, NH) and BigSkyMontana (City Motor Company, Great Falls, Montana), we have a series of solutions.
1) Coolant odor in the engine bay and outside the car. This odor may be pulled into the cabin through the cabin air intakes. There are a lot of possible sources for these odors ranging from leaky water pumps and hoses to a bad seal between the surge tank and surge cap to too much coolant in the system. If you have this issue, you will smell coolant odors in the engine bay and outside the car any time the engine has warmed to operating temperatures. If the engine cowl isn’t properly sealed, you may also smell coolant inside the car, regardless of heater setting.
a) PI-0762: Coolant Leak at Water Pump – (Jul 11, 2012) addresses leaks at the engine water pump and the mounting bolts. Update: http://www.cruzetalk.com/forum/25-service-issues/20897-pi0762d-coolant-leak-water-pump-aug-1-2013-a.html
b) PI-0740 addresses most other sources of coolant odors in the engine bay, but it doesn’t provide a real solution unless it gets your service department to find and replace a leak in the engine bay. Part of this PI is to put a hose on the coolant surge tank that “reroutes” coolant vapors from the top to the bottom the engine. This reroute has yet to help anyone and although it doesn’t appear to compromise the integrity of the coolant system, it’s ugly and useless.
BigSkyMontana discovered that the engine cowling that is designed to block engine odors from reaching the cabin air intakes can be very difficult to completely seal. He used a light source to help his service department identify and seal leaks in this cowl.
![CruzeCowlSealing_zps361ec4de.jpg]()
One part that no PI addresses in the engine bay is the coolant surge tank itself and its interface with the 20 PSI pressure cap. If the pressure cap doesn’t properly seal to the surge tank, you will get coolant odors anytime the engine heats up because the system pressure cannot be maintained and the coolant will boil at a lower temperature with the vapors leaking out through this faulty seal. Replacing the cap and/or the surge tank is the solution for this problem. In addition, dealerships apparently have no way to test this seal – they can test the cap by itself and pressure test the coolant system with the cap off, but are unable to test the integrity of the cap/tank seal integrity. You need to do a close visual and touch inspection of the surge tank’s upper lip and a visual inspection of the O-ring in the cap to determine if you have a problem at this interface. For more information on fixing this situation, see Blue Angel's http://www.cruzetalk.com/forum/25-service-issues/110049-fix-coolant-odors-coolant-loss-reservoir.html thread.
![capinfosm_zps3bd9fac6.jpg]()
![tankdefectsm_zps91d54d14.jpg]()
Finally, do NOT fill your coolant above the top of the arrow on the side of the surge tank. The top of the arrow is the “cold full” line for the engine coolant. Overfilling your coolant system is a guaranteed method for having major coolant odors in the engine bay and outside your car. Likewise and despite some members reporting the need to "under-fill" their coolant surge tanks to lower the pressure in the tank, I and the rest of the CruzeTalk Staff and Gearheads do not recommend doing this either because this will also lower the boiling point of the coolant mixture, with unknown impact on your engine's longevity.
![NA Cruze Coolant Surge Tank Cold Full Line.jpg]()
2) "Coolant” odor inside the cabin, but not outside the car. There are two known sources for this problem.
a) The first is a leaky cabin heater core and appears to be predominately a 2011 model year problem. Replacing the cabin heater core and the floor mats and sound insulation will fix this problem. You must replace the floor mats and sound insulation to insure you don’t have left over odors after the repair is completed.
b) The second and more pervasive issue is the glycol based lubricant on the HVAC duct gearing and air redirection shutters. This issue occurs anytime you run the heater and may or may not occur through all the vent options. Because this lubricant and the DexCool engine anti-freeze are both glycol based the two odors are very, very similar, which is why many people smelling this odor think the problem is with anti-freeze fumes coming from the engine bay into the cabin. The key to identifying the HVAC box as the source is that you do NOT smell coolant odors outside the car.
PI-0935: Odor from HVAC system with Temperature Control Set on High Heat is the corrective action for HVAC sourced “coolant” odor. This is a 4.7 hour major surgery on your Cruze, so it correctly directs your dealership’s service department to PI-0740 to try do eliminate engine bay based odors and their ability to enter the cabin via the cabin air intake.
3) Other odors ranging from dirty socks to other earthy smells inside the car indicate the presence of mold and/or mildew in the HVAC system. This smell can appear anytime you run the blowers or even during forced air induction into the cabin while moving. It does NOT depend on engine temperature or cabin temperature settings. I am including this issue because it can mask and confuse the odors from the first two problems, making them that much harder to identify and resolve.
The resolution for this is to clean out the HVAC system using the GM mold/mildew kit, ensure the HVAC condensation drain is clear and draining, and turn on the HVAC after-blow to dry the system after you use it.
When correcting cabin odors, replace your cabin air filter at the same time. It will catch and hold glycol, mold, mildew, potentially causing a lingering smell that makes it appear the problem hasn't been corrected, only lessoned. Also, there will be some chemical smell after these fixes are done. This smell is distinct from any other smells and will dissipate over two weeks to a month.
Additional threads, in no particular order, about these issues (I have "unstuck" and closed these threads):
http://www.cruzetalk.com/forum/25-service-issues/7736-pi0762-coolant-leak-water-pump-jul-11-2012-a.html
http://www.cruzetalk.com/forum/25-service-issues/11407-coolant-smell-resolution.html
http://www.cruzetalk.com/forum/25-service-issues/12369-pi0935-odor-hvac-system-temperature-control-set-high-heat-engine.html
http://www.cruzetalk.com/forum/25-service-issues/11235-antifreeze-smell-thread-v-2-a.html
http://www.cruzetalk.com/forum/25-service-issues/5843-antifreeze-smell-thread.html
In addition to BigSkyMontana, commutertg and their dealerships, I’d also like to thank Blue Angel, robby and other CruzeTalk members for their efforts in both resolving these problems and in educating me on how the Cruze’s coolant system operates. I’d also like to thank my service advisor, Jeff and his boss Jeremy at Ed Bozarth Chevrolet Park Meadows, Lone Tree, Colorado for listening to the symptoms as I reported to them about the cabin smells in my ECO MT and getting them fixed without trying to second guess my observations. Having a service department that listens to the driver’s observations is critical to correctly identifying and fixing problems with any car.
All pictures are courtesy Blue Angel.
Cabin odors in the Cruze have been the hardest to solve and longest running problems with our cars. Thanks in a large part to commutertg, (Banks Chevrolet, Concord, NH) and BigSkyMontana (City Motor Company, Great Falls, Montana), we have a series of solutions.
1) Coolant odor in the engine bay and outside the car. This odor may be pulled into the cabin through the cabin air intakes. There are a lot of possible sources for these odors ranging from leaky water pumps and hoses to a bad seal between the surge tank and surge cap to too much coolant in the system. If you have this issue, you will smell coolant odors in the engine bay and outside the car any time the engine has warmed to operating temperatures. If the engine cowl isn’t properly sealed, you may also smell coolant inside the car, regardless of heater setting.
a) PI-0762: Coolant Leak at Water Pump – (Jul 11, 2012) addresses leaks at the engine water pump and the mounting bolts. Update: http://www.cruzetalk.com/forum/25-service-issues/20897-pi0762d-coolant-leak-water-pump-aug-1-2013-a.html
b) PI-0740 addresses most other sources of coolant odors in the engine bay, but it doesn’t provide a real solution unless it gets your service department to find and replace a leak in the engine bay. Part of this PI is to put a hose on the coolant surge tank that “reroutes” coolant vapors from the top to the bottom the engine. This reroute has yet to help anyone and although it doesn’t appear to compromise the integrity of the coolant system, it’s ugly and useless.
BigSkyMontana discovered that the engine cowling that is designed to block engine odors from reaching the cabin air intakes can be very difficult to completely seal. He used a light source to help his service department identify and seal leaks in this cowl.
One part that no PI addresses in the engine bay is the coolant surge tank itself and its interface with the 20 PSI pressure cap. If the pressure cap doesn’t properly seal to the surge tank, you will get coolant odors anytime the engine heats up because the system pressure cannot be maintained and the coolant will boil at a lower temperature with the vapors leaking out through this faulty seal. Replacing the cap and/or the surge tank is the solution for this problem. In addition, dealerships apparently have no way to test this seal – they can test the cap by itself and pressure test the coolant system with the cap off, but are unable to test the integrity of the cap/tank seal integrity. You need to do a close visual and touch inspection of the surge tank’s upper lip and a visual inspection of the O-ring in the cap to determine if you have a problem at this interface. For more information on fixing this situation, see Blue Angel's http://www.cruzetalk.com/forum/25-service-issues/110049-fix-coolant-odors-coolant-loss-reservoir.html thread.
Finally, do NOT fill your coolant above the top of the arrow on the side of the surge tank. The top of the arrow is the “cold full” line for the engine coolant. Overfilling your coolant system is a guaranteed method for having major coolant odors in the engine bay and outside your car. Likewise and despite some members reporting the need to "under-fill" their coolant surge tanks to lower the pressure in the tank, I and the rest of the CruzeTalk Staff and Gearheads do not recommend doing this either because this will also lower the boiling point of the coolant mixture, with unknown impact on your engine's longevity.
2) "Coolant” odor inside the cabin, but not outside the car. There are two known sources for this problem.
a) The first is a leaky cabin heater core and appears to be predominately a 2011 model year problem. Replacing the cabin heater core and the floor mats and sound insulation will fix this problem. You must replace the floor mats and sound insulation to insure you don’t have left over odors after the repair is completed.
b) The second and more pervasive issue is the glycol based lubricant on the HVAC duct gearing and air redirection shutters. This issue occurs anytime you run the heater and may or may not occur through all the vent options. Because this lubricant and the DexCool engine anti-freeze are both glycol based the two odors are very, very similar, which is why many people smelling this odor think the problem is with anti-freeze fumes coming from the engine bay into the cabin. The key to identifying the HVAC box as the source is that you do NOT smell coolant odors outside the car.
PI-0935: Odor from HVAC system with Temperature Control Set on High Heat is the corrective action for HVAC sourced “coolant” odor. This is a 4.7 hour major surgery on your Cruze, so it correctly directs your dealership’s service department to PI-0740 to try do eliminate engine bay based odors and their ability to enter the cabin via the cabin air intake.
3) Other odors ranging from dirty socks to other earthy smells inside the car indicate the presence of mold and/or mildew in the HVAC system. This smell can appear anytime you run the blowers or even during forced air induction into the cabin while moving. It does NOT depend on engine temperature or cabin temperature settings. I am including this issue because it can mask and confuse the odors from the first two problems, making them that much harder to identify and resolve.
The resolution for this is to clean out the HVAC system using the GM mold/mildew kit, ensure the HVAC condensation drain is clear and draining, and turn on the HVAC after-blow to dry the system after you use it.
When correcting cabin odors, replace your cabin air filter at the same time. It will catch and hold glycol, mold, mildew, potentially causing a lingering smell that makes it appear the problem hasn't been corrected, only lessoned. Also, there will be some chemical smell after these fixes are done. This smell is distinct from any other smells and will dissipate over two weeks to a month.
Additional threads, in no particular order, about these issues (I have "unstuck" and closed these threads):
http://www.cruzetalk.com/forum/25-service-issues/7736-pi0762-coolant-leak-water-pump-jul-11-2012-a.html
http://www.cruzetalk.com/forum/25-service-issues/11407-coolant-smell-resolution.html
http://www.cruzetalk.com/forum/25-service-issues/12369-pi0935-odor-hvac-system-temperature-control-set-high-heat-engine.html
http://www.cruzetalk.com/forum/25-service-issues/11235-antifreeze-smell-thread-v-2-a.html
http://www.cruzetalk.com/forum/25-service-issues/5843-antifreeze-smell-thread.html
In addition to BigSkyMontana, commutertg and their dealerships, I’d also like to thank Blue Angel, robby and other CruzeTalk members for their efforts in both resolving these problems and in educating me on how the Cruze’s coolant system operates. I’d also like to thank my service advisor, Jeff and his boss Jeremy at Ed Bozarth Chevrolet Park Meadows, Lone Tree, Colorado for listening to the symptoms as I reported to them about the cabin smells in my ECO MT and getting them fixed without trying to second guess my observations. Having a service department that listens to the driver’s observations is critical to correctly identifying and fixing problems with any car.
All pictures are courtesy Blue Angel.
