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Venting Antifreeze?

(2013 Camry XLE) - About a week or so ago I smelled a whiff of antifreeze. I checked and there were no obvious leaks or puddles and the odor went away almost immediately. It happened again 2 days ago, and although there was no noticeable loss of coolant I decided this time I decided to get a pro to check out the car. I took it into Toyota and they gave it a once over. I was informed that this is normal - the engine will vent something once in a while and that is what I was/am smelling. Pardon me, but that doesn’t make an once of sense - venting antifreeze? Has anyone else heard of this and do I need to take it back to Toyota and be a bit more insistent that there is a problem here.

The cooling system on modern Toyotas use a pressurized reservoir. The pressure cap is a part of this. The cap’s job is to maintain pressure to a maximum 13-16 psi, whatever the factory tecommendation is. Occasionally, the cap will release some pressure to maintain that maximum. I believe this is the ‘venting’ the mechanic is referring to. When it releases some pressure, some antifreeze may also drain out if the reservoir is full. This is normal.

(whew) Okay, nice, glad to see I was wrong about this. Thanks, and thanks for the rapid reply.

+1 for @BustedKnuckles and just a little advice here. If you overfill your reservoir the same thing will happen until enough coolant is released to bring it back to normal levels. The “cold” and “hot” lines marked on the reservoir are there for a very good reason. You might want to pick up a new radiator cap or pressure cap if this problem continues.

Not to be a harbinger of doom, but an intermittently leaking head gasket will cause this too. If the reservoir is not overfull and a new radiator cap does not fix the problem, I’d have the car tested for the presence of combustion gases in the coolant. Does the car overheat at all? Is the temp gauge stable?

I once opened my hood after a drive and there was coolant all over the engine compartment (blew out of the coolant tank). I never smelled anything. Are you sure it’s coolant?

Try replacing the cooling system pressure cap.

If the cap is weak it’ll open below its specified pressure and allow the cooling system to vent when it shouldn’t.


The car is pretty new (2013, <6K miles), so if it’s a head gasket, Toyota has some ‘splainin’ to do. I did take it in to the dealer and they saw nothing untoward. There were no other signs of trouble - no overheating, temp gauge looked fine, and no mysterious green puddles were visible.

@Tester is right. Radiator caps are cheap, they do fail sometimes, and then coolant goes all over. You might hear boiling after you turn the engine off. Buy a new cap, wait until morning when the engine is stone cold, and replace the old cap with the new one.

I smell coolant on every '13 & '14 ES350 (same powertrain) that I work on if the engine is hot. None of the cars are leaking or low on coolant.

The coolant reservoir on previous years was near the right fender. On 2013/2014 the reservoir is mounted to the fan shroud close to the engine. I believe the odor is from hot coolant in the reservoir.

no mysterious green puddles were visible.

With a Toyota it would be red/pink.