my 4runner has about 25k miles on it (2016 limited). I have noticed a faint smell of coolant the last couple times of driving (after walking around the front of the 4runner - is when i smelled it).

Levels in the overflow are exactly the same. is this common? i see if the older forum postings (3rd and 4th gen), this seems common.

Possibly a system purging and smelling from the reservoir?

I'd check that radiator cap is tight as well as the cap on the overflow tank. Also check all coolant and heater hose connections. Make sure they are tight and not weeping any coolant. Also check around the water pump and radiator drain plug.

i just rechecked. the smell definitely is near the radiator overflow. the cap and everything are on tight there...

Hi changingtime,

I my opinion this is NOT AT ALL common or normal. If you're smelling ant-freeze/coolant, then there is some coolant leaving the cooling system; even if it is in the vapor stage! Like you, my 2012 4Runner (Limited) has very low mileage '20,170' miles on the clock and no sweet odor of anti-freeze seepage at all.

If I were you, I'd start by placing a clean flat moving/storage cardboard box under the truck directly underneath the radiator, hoses and coolant bottle area when the engine is hot, or normal operating temperature and leave it there over-night. When you pull out of the parking space/driveway, I'd examine it to find any spots or evidence of wetness on the cardboard as a starting point.

If nothing is found, I'd take it to the local 'Auto-Zone' and have them do a pressure test using a hand held air pump from 12 to 15 psi. The system must hold system pressure for a given amount of time... that amount of time would depend on the engine temp and rate of cool-down while under pressure.

But if it does leak, there should be evidence of coolant discharge from the origin of leakage e.g., loose hose clamp, water pump weep-hole or seal...etc! The leak can be very small at this point so be sure to give it time to start showing wet spots near or around the source of leakage! Please be sure to let us know what you find after doing some simple tests at home or Auto-Zone! 'Best to you'

rig

Also you may want to remove your skid plate for a while to better check for leaks on the cardboard Rigtec mentioned. You might see something on the skid plate when you remove it you can't see from above.

A couple of other things to check are radiator cap gasket. Overflow hose and overflow hose tube (where hose connects to radiator just under cap) for splits, holes or cracks. Radiator may have a crack too. Any hose may have a pinhole leak that allows steam to escape. Pressure test should find this.

Not sure where the heater core is on the 5th gen but they are famous for sweet smell antifreeze issues in other vehicles.

Ditto on removing the skid plates + rent a cooling system pressure tester from one of the mass marketer auto parts places. How-To's on youtube if needed.

Coolant leaks can sometimes be hard to see. A pressure tester helps.

Same exact problem on my 2016 Limited with 20,000 miles. I will have to check the things listed in here as well.


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went to the dealer this am...they pressure tested it for 45 minutes. no leaks. they believe that due to the extreme heat we are having it may have briefly leaked out of the reservoir. which is where the smell is. they cleaned it up and i didn't smell it after driving...

What level is the coolant in your reservoir? We would occasionally smell coolant in our RAV4. It turns out it correlated to the dealer topping off the reservoir. Once it pushed out a pint or so no more coolant smell. Normal seems to be right at or slightly below the low mark.

I would say normal, just based on my experiences driving in extreme heat, and / or off roading in mild to extreme heat. Even with new vehicles.

With that said...good on you for having it checked and even better that there were no issues!

my level sits just below the F line most of the time and almost right at it when done driving...

Just checked on my 4Runner and it’s slightly below halfway between the marks. You can see there’s s huge amount of headspace above the full mark.

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Remove the shroud and look for any signs of leakage.

My 4R is 70 miles away at a dealership & I'm driving a loaner while they wait on a replacement radiator. It may have started small, but it pissed out a gallon of antifreeze today and tried to overhead on me. 36 bucks in toyota antifreeze and 40 miles later, it was at the dealer....