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Smell Of Engine Coolant From A/c Vents


flanker271
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Hi guys,

This symptom started a week ago. When I start up my LS for the first time every morning, I noticed a strange smell coming from all four of my vents. I had a/c off. Since I don't know what R-12 freon smells like, I can't rule out that this smell is the freon. In about 10 minutes when the car warms up the smell is gone.

Should I be concerned about this problem at all? If its coolant leak, is this a sign that my waterpump is leaking? If its a freon leak, could it be my compressor or the expansion valve?

I don't see any white smoke from the exhaust when starting the car, if this helps.

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I don't think freon has an odor, or at least not a noticeable one.

If it is anti-freeze you can watch the reservoir level over a few day to see if it declines.

The most likely cause is mold and mildew "dirty gym socks" odor.

In that case search google for:

Denso demist odor

Or read:

http://www.airsept.com/eed.html

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I think that coolant has a fairly distinct smell that is different from the "gym socks" that wwest mentioned. If it is in fact coolant that you smell it is most likely coming from the heater core. During cooler weather when you run the heat you can actually get a film buildup on the inside of the windows if the core is leaking.

Now if it is not coolant then wwest has most likely already pointed out the culprit - mold/mildew buildup inside the vent system. You can try spraying a light disenfectant through the intake plenum. Keeping the A/C on while the car is running seems to control the odor in many cases, but ultimately you'll have to kill the source of the odor to eliminate it all together.

I would doubt that it is a freon leak (are you getting a lightheaded buzz while driving? ;) ) Usually you will see some smoke/steam/mist/fog (choose your description) coming from the vents if you are losing freon or if your evaporator isn't working properly. A freon leak could be coming from anywhere within the contained system so the compressor and expansion valve are possible places for a leak, but not the only spots - you could easily have a cracked hose or bad coupling.

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I'm pretty much determined that the smell belongs to the coolent. One of my dash light (something that looks like a radiator) lighted up this afternoon. Reading through the manual this light indicates low engine coolant. Sure enough, the coolant level is about 1/2 inch below the cold line. The coolant fume is toxic you say? I'd better get this checked out.

Will keep you guys posted. By the way, I always had the climate control setting on "bring in fresh outside air" setting, not the "interior recirculate" setting. What setting do you guys prefer on a hot summer day to make the A/C more effective? I'm talking about during long distance drives, not the initial desire to bring the interior down quickly. The manual says "besure to switch to the 'fresh air in' setting once the interior has cooled down.' "

Addition:

how big a job is replacing/repairing the heater core?

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well if its the heater core, you have two choices, either you fix it, this includes countless hours of work since you have to remove the ENTIRE DASH, front seats, center console, etc. Or you can give up the heating feature by bypasing the heater core. I had to do this a long time ago on one of my cars, but since i lived in florida, I didnt care much for heat. It was either the $5 dollar bypass fix, or 12 hours worth of labor. Lets hope its just a hose leak, and not the actual heater core.

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Given that you only have the smell for a few minutes after initial startup I rather doubt that it's the heater core. Look under the hood at the top center of the firewall and be sure the hot water valve isn't leaking slightly at one of the hose connections.

That's a common failure point.

When the car is just sitting there is no real pressure within the coolant system whereas when running and especially at high engine RPM the coolant is under pressure. So my guess is that when the car is sitting a slight leak allows the coolant to "pool" somewhere and once that pool has evaporated you don't have the smell.

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Coolant smell comes from coolant. What happens when you fill the coolant reserviour to full is that when the car is hot it overflows. The smell is probably being drawn in from that. Try running the car with the climate control button on recirculate and see if the smell stops. I'd look at the reserviour and see if you can see where it leaked out. Another indication of a heater core leak is that the window fog up on the inside especially at night and in humid weather.

I had no idea replacing the heater core was so hard on these. It sounds like they built the car around it.

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Hot summer day.....

During the summer months I remove the servo cable from the aforementioned hot water metering valve and tie it closed with a tie-wrap.

Improves A/C efficiency immensely.

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During the summer months I remove the servo cable from the aforementioned hot water metering valve and tie it closed with a tie-wrap.

Improves A/C efficiency immensely.

May I ask how you are you measuring this improvement in efficiency? What specifically improves?

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I had no idea replacing the heater core was so hard on these.

Yeah a heater core failure on an LS400 can cost thousands to replace due to the massive labor involved in getting to it. The only reason a heater core could ever corrode and leak is because of use of aftermarket antifreeze / tap water in the cooling system. Here's are some pictures showing how the factory original coolant mixture (50% Toyota antifreeze + 50% distilled water)

is capable of completely eliminating corrosion in Toyota / Lexus cooling systems if the owner continues using it at replacement time instead of using aftermarket antifreeze and / or tap water.

http://www.saber.net/~monarch/coolanta.jpg

http://www.saber.net/~monarch/coolantb.jpg

http://www.saber.net/~monarch/coolantc.jpg

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The recirculate setting made the smell worse. I checked under the hood near the upper firewall, there are some dried coolant residual on all three hoses and some residual on what appears to be a valve looking thing (heater valve)?

There are also some dried coolant residual on the top of the coolant reservoir near the pressure release cap.

I filled the coolant to the hot level when the car is warm 1 day ago, but its 1 inch below the cold line when I checked it this morning. I definitely have a leak somewhere.

Off to Toyota dealer I go... <_<

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Took the car in for inspection around noon, just received a call from the service representitative from Precision Toyota of Tucson:

According to the guy, my waterpump and some rubber hoses are leaking. He didn't explain why I had the smell coming from my a/c vents. In addition, he mentioned the following:

--air filter is dirty (I just replaced it 2 weeks ago)

--ps pump is leaking (I had the pump refurbished 1 1/2 year ago at the same dealer)

--ps rack is leaking (my ps reservoir is still full after 1 1/2 year)

--master brake cylinder is leaking, he quoted me $2100 for parts and labor!

--one of the pully bearing on the accessory belt is torn, causing extra load on the engine

After speaking with him on the phone I took a deep breath and told him that I'll call back. I don't know how much more I want to spend on this car, but its my only transportation right now. I want you guys' opinion: whats urgent and whats not. I've never heard about LS having brake problems. Can leaky master cylinder suddenly cause a catastrophic brake failture? Can I just top off the coolant reservoir once a week and get away with it for now?

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Boy that dealer appears to be taking you for a ride! Monitor the fluid levels in the PS reservoir and brake master cylinder reservoir. If the levels are steady then all is well in the PS and brake systems. Toyota brake master cylinders generally last at least 25 years - more if the fluid is changed occassionally, less if someone accidentally put the wrong kind of brake fluid in the system (system requires DOT 3 fluid). It is highly unlikely any coolant hoses are leaking if they are the factory original hoses and hose clamps.

I'd personally take the car to another dealer in Tucson to verify whether or not the water pump / hoses are leaking and if any pulley bearing is worn out. If the coolant leak is genuinely from the water pump then you might want to replace the timing belt at the same time. If just a hose(s) is leaking then the replacement cost will be minimal.

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The previous must have not changed the waterpump when the timing belt is changed, which is at 112,000 miles. Thanks for all your help. I'll keep her going like this until it dies, then I'll figure out what to do with it.

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While, when, you are driving the car the engine cooling water jacket temperature is regulated "limited" to ~180F (no attempt to be precise here). Once you turn the engine off the ability to regulate the engine water jacket temperature is significantly reduced and oftentimes the temperature will rise temporarily almost to the point of boiling.

It is at this time that the hoses, hose clamps are most likely to leak.

So, you shut the car down at the end of the day, the water jacket temperature (and PRESSURE!) rises temporarily forcing a bit of coolant out, and now when you restart you must endure a few moments of odor.

Ignore that dealer but fix the coolant leak before it gets worse.

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  • 17 years later...

We have a 2022 ES with 5000 miles.  My husband says he smells antifreeze, yet the car is not overheating.  Checked by dealer and could find no leaks???????

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Overheating is not a symptom of a coolant leak unless it's a big leak.

When does he smell antifreeze?  All the time, when the heat is on, when the AC is on?

What method did the dealer use to determine that there were no leaks?  Visual inspection of hose connections or pressure test?

Your car is under warranty; its's probably going to take you being a PITA until you get some satisfaction.

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I don’t see that they conducted the pressure test on the work order.  They may have figured the car was too new to have a bad heater core or we were just imagining it!  Nonetheless, I have a call into maintenance to ask them this question and would it be possible to check.  I don’t feel comfortable driving in a car that may be emitting toxic fumes.  Better to be safe and check.  I did read that a “sweet smell”” in a car cabin can indicate a bad heater core.  Now I am wondering if we did the right thing and give up our 2016 GS350 F Sport for the ES simply because our Lexus had 3G technology and was no longer being produced.  We never had a problem with it and it was AWD ( and that was our 3rd GS)!!!  Also, noticed slight hesitation in car as you accelerate!!!!

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