white smoke with sweet smell on cold starts
 

hi All,


l used to daily drive my 2012 infiniti G37s coupe and for last two to three months, i have been starting it may be once or twice a week for short trips within the city.


I started to let the car warm-up for a minute or two before driving it and it is when I started to notice sweet smell and white smoke coming out of the exhaust till the car warms up. during warm up, the car idles rough at around 1200 rpm and slowly comes down to 600-800rpm as the engines reaches its operating temparature.


my first thought was coolant leakage and started to check the levels of coolant in the reservoir. the level remains same although i have to admit that i never drove the car for long distances since noticing the smell.

I acquired the car in July 2018 and it had around 43,000 kms then. now, it is close to 50,000kms. I did got it checked by local infiniti dealer at the time of buying the car and they told me that the car is in very good condition.


i am still concerned and am very much tempted to try to use gasket sealants liquids available in autozone. the car is due for regular maintenance this month.


below are the checks I did -


1. no change in the level of coolant in the reservoir(white box with min and max)

2. no bubbles observed from the coolant next to the engine

3. after letting the car warm up, there is still very small amount of white smoke coming but without the smell. I gave the accelerator hard pushes for couple of seconds and observed that the density of white smoke increased a little with smell and also observed small drops of water dripping from the exhaust.

the water was colorless and odorless. i let the car idle again for couple more minutes and this time there is no noticeable white smoke or smell from the exhaust.

4. Engine oil cap looks clean beneath with no milky substance observed.


sorry for the lengthy post. kindly let me know if I need to be worried about my car.


Regards and Thanks,

Sai Bollineni

Your symptoms imply a leaking head gasket(s). A cracked block is also possible. I don't know if the intake manifold has coolant passages; if so, there could be a crack there.

thank you for replying.

just asking for my understanding, the smell and smoke usually goes away after sometime and there is no difference in the coolant levels in coolant leakage cases. so, how can i confirm if it is a coolant leakage?

i saw some posts and videos where there is continuous white smoke from the exhaust even after the car is heated up which is not the case with my car. so, does this still mean that there is a possible leakage in my car?

Proper level in the radiator? Color?

thanks for responding. the coolant level is always a little above MIN level mark in the reservoir(when the engine is cold). and the color is green with no oil residue observed floating on it when its cap is opened.

Try again?

I restarted the car again now(the weather is sunny at present) and the the idle was smooth and no smoke or water was observed from the exhaust. I let the car run for a minute or so and then pushed the accelerator hard couple of times. i then observed light white smoke from the exhaust and also little water from the exhaust. after few seconds, the white smoke disappeared tho.

Red circle = radiator cap
Blue circle = reservoir cap

What is the level under the cap circled in red?

Attachment 183634

Check the oil too.

DOes it overheat?

You could have a leak somewhere. Hose maybe? Water pump?

If I remember correctly, the throttle bodies are supplied with coolant, ostensibly to prevent icing.

OP, I think there are test strips that will reveal if there are hydrocarbons in the coolant. If exhaust is mixing with coolant, you have a failed head gasket and/or cracked head.

the level under the red cap is full. when I opened the cap, the coolant is till to the top and with no oil residue nor any air bubbles observed.

if the coolant is entering into the engine block, should I notice a drop in the coolant levels in the reservoir and also a continuous white smoke from the exhaust. is my understanding correct?

As of today, the coolant level is observed from last few weeks to be just above MIN level in the reservoir(white box) when the engine is cold and between MIN and MAX after driving the car for a while.

since observing the smell after cold starts, I only drove the car with in the city. i drove it for around 1 hour in mild traffic with couple of traffic lights and didn't observed any abnormality in the temperature gauge. I am planning to drive the car on a highway to a near by town (around 3 hours to and fro) in noon just to check if the temperature gauge is raising beyond the usual level(between low to medium).

I tried checking for leaks but couldn't find any noticeable leaks at the hoses or pumps.

thanks to everyone for responding. I might be overthinking or the car does indeed might a problem. I just want to make sure that all the checks are being performed before taking the car to a mechanic.
i don't have complete confidence on the infiniti agency here in my city and the mechanics usually take you for a round. i had a very bad experiences with my previous car, Altima that had transmission issues. So, I want to make sure about the cause of the smell before checking with a mechanic.