Observation with newer vehicles - coolant smell

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Aug 28, 2017
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Location
Virginia
I've always driven junkers/older vehicles and have developed a keen sense for leaks/smells, etc. It has served me well.

I have noticed that many newer vehicles, even going back 10 years or so, will produce a distinct coolant smell on startup. I notice it in parking lots on stranger's vehicles, but also with vehicles belonging to family members . . . that I know are not leaking internally enough to been seen by a decreasing coolant level.

It seems like it's a burning coolant smell, but could it just be the system venting? . . . but I wouldn't think it could vent through the overflow on a pulse of pressure at start-up.

Is there any explanation dealing with the pressurized expansion tanks or new coolant system design? Is there an emissions system smell that is similar to glycol?

It has been one of those things that has consistently baffled me . . . "This many new cars can't be burning coolant."
 
All I can say is that I've experienced the same thing.

As vague as the "data" is, I wonder if the effect diminishes over time.

Could the aroma be that of today's plastic / rubber compounds?
 
My 4Runner does this. Never a drop of coolant on the garage floor and coolant level always in the same spot. Almost 35,000 miles and still does it.

I've always accepted it as normal. Would be cool to have an answer for it.
 
We have a number of Subaru Outback and Liberty's (Legacy) at work, and they all smell of coolant when getting out after a decent drive. The coolant level is always spot on though.
 
Originally Posted by WyrTwister
Did you say you smelled it inside or outside of the car ?


For me, always on the outside. I've never smelled it in the truck...even with the windows down.
 
I think the smell comes from/through the hoses. I've noticed coolant smell after replacing hoses, of course that could be from spilled coolant during replacement.
 
My Focus was the first car I had that did this, and my 2018 Subaru does it.

I think it has something to do with the chemical makeup of the "green" ecoplastics that are on everything now.
 
Newer cars produce much heat under the hood that makes all the dressing on plastic covers heats up and smells. I also noticed on mine the exhaust stinks for couple of minutes after I shut off. Claimed that this is caused by low sulphur fuel and cats run hotter giving off the odor.
 
I noticed my 2000 Mustang smelled like coolant in the exhaust after I started using E-15 gas (which is really good, BTW). I get similar mileage and more octane for less cost (89).
 
. . . very, very glad that it's not just me!

I notice it outside, which is why I assumed it was the exhaust. When you start a vehicle and back through it's own exhaust (windows down) is always when it seems most pronounced.
 
Originally Posted by Miller88
I think it has something to do with the chemical makeup of the "green" ecoplastics that are on everything now.

I agree.
I think it has more to do with the plastics under the hood, than the coolant.
I don't smell anything like that when starting/driving my 31 year old BMW.
 
Originally Posted by MVFarms
I have noticed that many newer vehicles, even going back 10 years or so, will produce a distinct coolant smell on startup.


People perceive smells differently. What smells like coolant could be from any number of compounds in the exhaust or under the hood as plastic and metal heat up. I once bought a car and swore I could smell watermelon every time I drove it. And no, not from an air freshener.
 
Our Jetta smells of coolant after driving, as others have said it may just be hot plastics.
 
I've noticed sweet smelling exhausts more in the winter, likely from richer mixtures during cold starts.
 
Check the over flow tank. Tanks with just a plastic lid don't seal, they vent. Tanks with a radiator cap don't. My 2018 RAM 1500 3.6 has the kind that has a dipstick in the over flow tank. I smell antifreeze every time after I drive it. Wife's 2019 Charger 3.6 has a radiator cap on the over flow tank, no smell ever. The worst I had was my 2017 Jeep Wrangler 3.6, it reeked of antifreeze, but NO leak.
 
Its definitively antifreeze, it has a very distinct smell.

I smell it on my 13' Honda Civic which has a radiator cap.
But the level like others have said is always ok. So, I dunno, what's up.
 
many older cars have different cat warmup emissions ( cycles through paint smells, and many others) and these are often varied within their warmup cycle. when working at a parking lot gate (1976-77) I noticed this a LOT.

modern 4 wire sensors may abbreviate this a bit but the cat warmup heat seems to be ONLY provided by exhaust gas, which varies a LOT with mixture,load, humidity, condensate, trims, manifolds and pipe temps, probably Tstat and intake air also. just because the burn is a blue light does NOT mean the same chemistry out the tailpipe.
glycol burning seems to have a distinctive smell but it can possibly be spoofed by other vapor blends, and hidden enough to be undetectable by many. hot glycol on hot engine has a different smell than cat-burned glycol. (glycol will orange-heat a cat if too much is leaking)

88 windstar intermittently coded a rear-bank-lean until the day it hydrolocked a cyl at 60 mph and put a rod thru the block, which seemed to be common for many 3.8's and no smell, no detectable smoke, minimal coolant signature as preliminary symptom. MANY thanks to ford for their economic choices of OEM headgaskets, scrapped that vehicle value at 96K. ($5K replacement engine plus install$, $6K vehicle, no core rebate).
 
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