Sweet smell, but car runs fine, no overheating ??

[Complexity]

For the last 6 months, I've noticed a smell from my 1997 Avalon after I've driven it and parked. I cannot smell it inside the car. The smell does not come through the a/c or heater. I can only smell it when I have driven my car, park, and then get out.

The car drives great with no changes that I can find. The smell reminds me of coolant when a car overheats, but the gauge shows normal temperature (directly in the middle of the gauge when warm). I live in Houston, TX and there was no overheating issues even when driving for an hour in over 100°F temps. The car has not been serviced during this time so no one has added coolant.

I'm going to take my car to the dealer to have it serviced, but I wanted to get some ideas from others as to what that smell might indicate. If it is probably something minor, then I'll take it to the closer (but not as good) dealer. if this sounds like it could be something major, then I'd rather take it across town to a better dealer.

Again, the only symptom I am having is the smell. It's a sweet smell, and I can only smell it when I have driven the car, park, and get out. Any ideas what it could be?

Thanks, in advance.

[Jigg007]

Is your coolant at the correct level? Perhaps the radiator cap is not completly sealed either. Coolant can boil off if the system is vented/not pressureized.

Though, I have the same problem on a friends 01 blazer.. so I cant say much

[Complexity]

I have no idea; I don't work on cars (sorry, non-mechanic woman here). I can go look tomorrow, but I'm not sure how to tell whether the coolant's at the correct level or not. It just seems odd that the temperature wouldn't show signs of overheating after so long. I don't baby the car.

How much coolant would need to boil off before the smell becomes detectible? Maybe it's just a tiny amount each time? That might explain why I'm not seeing any other symptoms?

[Jigg007]

There are two fill caps for the cooling system. there is the steel radiator in the front of a vehicle with the radiator cap ontop. Besides being removed, this cap has two positions: sealed and vented. When the car is cool, remove the cap, you should be able to see coolant with the cap removed, it is a green or pink color. Put the cap back on, it should turn and stop, this is the vented position. Then similar to a pill bottle you need to push the cap inwards and give it another turn, this is the sealed position.

Above the passenger wheel there should be a translucent bottle, this is the coolant overflow tank. It also has a cap, but a simple twist on, twist off. There are level markings on the side of the tank. I ca'nt recall if the avalon has ADD or FULL markings, but those are self-explanatory. There are also COLD and HOT variants, which are the fill markings depending if the coolant is cold or hot.


Imagine you have a sealed box full of water, and water boils at 100C. If the sealed box is heated to 100C and above, the water will not boil. Why? Because water's vapor state takes up more space than its liquid state. As the temprature increases well past 100C the pressure will continue to rise as the liquid tries to change into vapor, but cannot. That is untill, the box is vented or breached, causing the liquid to boil instantly.

Same with your cooling system, it is doing its job because the coolant is removing heat from the engine, however it is boiling off in the process. However you're not currently overheating because there is still enough fluid in the system, and very little coolant needs to boil for you to notice the smell.

[Complexity]

Thank you! I actually understood everything you said. Very helpful! I will check the fluid in the morning, and I'm particularly interested in seeing if I can tell if the cap is on completely or not before I take it off. I'll probably have to do some googling to figure out where everything is, but none of this is difficult stuff (my first car was a vega from long, long ago so coolant issues is something I learned in my early days of car ownership).

It would be so wonderful if this is all that's wrong. I have always loved my Avalon. I'm the original owner, and I have never had a car run so well with so few problems. It's getting up there in the years and miles now, but it still runs so well, I'd hate for anything major to go wrong with it. I don't want to let go of it yet or have some major mechanical repair screw it up.

I'll let you know if I find anything. Thanks, again.

[BMR]

It doesn't take much of a leak to make enough of a stink to be noticed. I used to have a Chevy that once did was your Avalon's doing. It turned out to be a minor leak where the radiator hose connects to the engine (actually, the thermostat housing). It would drip a drop every 10 seconds or so. Not enough to make a puddle under the car. It would evaporate away long before it dripped down that far. Took me a little while to find it. I noticed a pile of white crusty stuff; dried up antifreeze.

[NRecob]

Not to get off on a tangent but another reason to get this checked/fixed is if there is a leak this coolant contains ethylene glycol which is HIGHLY TOXIC to animals like cats and esp. dogs. They're attracted to it because of it's sweet smell & it can KILL even in low doses.
--
Hope you get it all fixed up and glad to hear from another happy Avalon owner--I think they are AWESOME-I've got 180K on my '95 and it runs GREAT.

[Jack Deth]

my old ford had a weepy hose connected to the water neck up on top of the block. it didn't leak enough to notice the coolant level dropping, but just enough to keep a little recess nearby in the block wet. it would get warm there and make the smell, but never got hot enough to boil away.

[Complexity]

I haven't checked it yet, but what you are all saying fits perfectly with the symptoms I've noted and is very likely what's happening with my Avalon.

I'm going to see if I can get my daughter's boyfriend to look at it when he's over a little later. He knows a little about mechanical work on cars so he might be able to spot signs of a small leak. From what I'm gathering, we need to look for a white, crusty build up somewhere along the coolant system, especially anywhere there are connections (radiator cap, hoses to other parts, etc.).

Thanks, again, for everyone's help. I greatly appreciate it. If this does turn out to be the problem, then I can be certain it will be fixed when I take it in for servicing. Telling these guys such a vague symptom like "there's this smell..." often gets overlooked and unrepaired, causing unnecessary hassles for all involved.

[Complexity]

Okay, he looked at the car and showed me what he found. There's moisture at the top of the radiator where he says the radiator and fan shroud come together. That area looks like there are a series of clips (but they're not actually clips) with a thin rubber strip. It's wet with a reddish tint liquid which he says is the antifreeze. He also found antifreeze on the fan blade underneath, but there isn't enough coming out to actually drip onto the driveway under the car.

I'm also low an antifreeze. The overflow reservoir just has a tiny bit in it at the bottom with the engine cold.

I looked at the oil from the dipstick, and it looks normal (but dark so it needs changing which doesn't surprise me). But it didn't look white or foamy which is what I had read would be a sign of water mixing with the oil. So I'm happy to see that.

I have the car scheduled to go into the shop on Monday. The only time I have to drive it for any real distance is tomorrow. I'll keep a very close eye on the temperature gauge, and if I see the temperature go even slightly above it's normal setting, I'll turn the heater on and pull over immediately. I will not drive it at that point.

I'm guessing they'll need to replace the radiator. I'm actually relieved that's all it is and not something more serious like a leaky gasket or cracked block. I hope to keep driving this car for a few more years. I'm no where close to wanting to let go of it yet!

Thanks so much for everyone's help! I really like knowing what's going on with my car when I take it in for repairs like this.

[fourwheeler]

why don't you take with you on your trip a couple of gallons of water. If you notice the temp creeping up, pull over and refill your reservoir using an old rag or towel to slowly loosen the cap. Make sure you open it slowly, the coolant will be hot and may try to escape quickly. You can also wait a few minutes with the car off for the pressure to subside.

That way you can continue on your trip and you still won't hurt the engine. This will work until you see the dealership on Mon. Good luck.

[Jack Deth]

if they offer you an all-metal aftermarket replacement, take it.

[Complexity]

Originally Posted by fourwheeler

why don't you take with you on your trip a couple of gallons of water.

Mainly because I didn't think it would overheat given how long this has been going on.

But even if it did overheat, I don't have a real temperature gauge. I only have what I've known to be called an "idiot" gauge. So I would not be able to determine the real temperature prior to opening the cap. If I remember right, the heated coolant would be under very high pressure which would spew out if I attempted to open it up while its overheated. Without proper gauges, I wouldn't know when it would be safe to open it.

So... I know just enough to know to not go opening it up without caution, but not enough to know when it would be safe. Under those conditions, it would be best to just pull over and do what i can to ensure the car does not go into a full overheating episode.

Originally Posted by Jack Deth

if they offer you an all-metal aftermarket replacement, take it.

Is this something I should ask for? I don't mind putting good money into my car. I intend to drive it for a few more years so reliability is much more important to me than saving a few dollars in the short run.

[Jack Deth]

the plastic tank to metal tubes joint is a common failure point in composite radiators. had one fail on a 94 explorer the same way. it'll drip for a long time before you start losing coolant fast enough to become a nuisance.

http://www.radiatorbarn.com (whom i've done business with years ago) offers an all-metal replacement for $150, so they are being manufactured. if you went to an independent shop, you could inquire, they may be willing to get one for you. otherwise, don't lose sleep over it. a good quality composite radiator will probably outlast the car anyway at this point.

[pmesfun]

If you going to the dealer, the oem toyota radiator is $450 alone, plus labor. What I would do is get a TYC Radiator(KoyoRad) from Rock Auto and have an independent shop or even your daughter's boyfriend can install it. Pretty straight forward. This will save you alot of money.

TYC Radiator:
http://www.rockauto.com/catalog/moreinfo.php?pk=1374260

The transmission cooler lines may need replacement also.