Coolant smell troubleshooting

Howdy y'all,

A while ago I started noticing a coolant smell. I couldn't find any leaks on the ground, and couldn't find any obvious leaks looking under the hood or around the radiator. I checked the coolant level, looks normal. I noticed the coolant smell seemed to come from the engine. I can't find any white smoke coming out of the tailpipe.

I don't really have any tools, but I had my dad help me a bit and we found one of the spark plugs loose / some oil leaking there, which turned out to be valve cover gasket. Still doesn't explain the coolant smell though.

So I brought it into a shop, and they called me back confirming what I already know. They also could not find any leaks in the coolant system and tested the head, said head was fine too. So I'm getting new spark plugs and valve cover gasket, I'm told I should test it like that.

I still don't feel confident that anything is really fixed. Where would this coolant smell be coming from if it's not head gasket, heater core, or radiator? I don't get it. It's a 2004 5-speed hatch with 124,000 kilometers.

Turn on the heat and see if the smell gets stronger. if it does, coming from the vents, chances are its the heater core. Did the shop pressure test the system? cause that's how you'd find out if it was leaking

Yes they did the pressure test, they said there was no leak in the coolant system. After getting the car back and driving it a while, I haven't noticed any smell so far. All that has been done so far is replace spark plugs and valve cover gasket. It doesn't make any sense to me...

My 2010 has the same smell under the hood. I've put UV die in it and still haven't found a leak. It's only needed about a pint of coolant in 18 months so I suppose it could just be evaporating through a normal vent. :dontknow: The coolant reservoir is pressurized and I'm not sure exactly how it is vented...I'll have to take a closer look one of these days.

If the amount of coolant lost is slight or negligible, it doesn’t pay to worry over it. My Aveo is too new to have this problem, but other cars I had have had slight leaks. One could only be smelled under the hood when the motor was hot. That was probably a leak at the head gasket, and it would lose a few ounces per month. Another car I have drips a few drops of coolant only when parked overnight in my garage – I can’t find where it is coming from at all. Another car of mine has a smell of coolant through the vents in the cabin only for the first ten minutes after startup – that’s probably in the heater core. These sort of things are not worth losing sleep over. Just keep an eye the coolant level monthly to be safe.

I beleve that coolant is toxic. Exposure to it, even small amounts, over a long period of time might be unhealthy. Probably best to make some effort to locate the leak. Is there a doctor in the house to give a second opinion?

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Originally Posted by wuwei37405

I beleve that coolant is toxic. Exposure to it, even small amounts, over a long period of time might be unhealthy. Probably best to make some effort to locate the leak. Is there a doctor in the house to give a second opinion?

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Unless you are drinking the antifreeze or the smell of it in the cabin is is overwhelming, it's not a health risk. The OP didn't say that either was the case.

Belief is one thing, reality is another.

Well The reservoir on the 2010 is pressurized. however the cap will only allow up ~15PSI to build up. If the pressure in the coolant exceeds that, the cap will vent some pressure out to bring it back down to ~15PSI

So far so good after replacing valve cover gasket no more smell...

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Originally Posted by byron84

So far so good after replacing valve cover gasket no more smell...

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That doesn't make sense. If you had a leak from the valve cover it would be leaking oil - not antifreeze.

The head gasket is another story...

Maybe the smell was oil....

I know it doesnt make any sense. But the smell was there before and now it is gone. I had several other people take a sniff so I know I'm not just imagining it. Kinda worrisome...

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Originally Posted by thehunterooo

Maybe the smell was oil....

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I know what oil and coolant smell like they are very distinct... And the people i had look at it do all their own work on their cars so its not like they are clueless. When i finally brought it to the shop they also noticed the smell but didnt find anything that would cause it.