Coolant smell and loss, but no leaks - autocross edition

Hey all.

The car is a 2012 Focus (base).

At the autocross on Sunday, and after about 6 runs, back to back to back (my son and I, consecutive run groups, A then B), I noticed a coolant smell coming from the car - I popped the hood noticed the overflow coolant tank was pretty low (a little below min) and added a bit of water to it to get it to max. No leaks anywhere, no coolant dripping no matter where we looked. Figured some had just bled off over the course of 3-1/2 years.

Let it cool with the hood up for a bit, closed hood did run number 7. After the run, popped hood, smelled coolant, and the overflow tanks was again lower than what i had filled at half again below min. Pulled the cap, and with the pressure relief got a rush of coolant back in the overflow - now at half again above min. I still had one more run, and my son and I both still had our time only runs (would've been another 9 runs total), but we canned them completely, no more autocross runs for the day.

Worked my turn on the course, let the car cool with the hood up the entire time. No further loss of coolant, checked high and low for leaks, nothing, all hoses and connections with radiator circuit bone dry.

No steam coming out the exhaust that we noticed, car ran fine, we went to lunch after the event - drove the car about 5 miles or so, got to the restaurant, popped the hood, no coolant smell, no leaks, etc....

We drove the 90 miles home, no issues to report, still no leaks, etc...

Best I can figure, with all the runs back to back to back, we were running high temps, cooking the oil, over taxing the cooling system, and with the extra heat and pressure maybe it was "venting" past the hose connections (I think they call them constant pressure clamps?)?

Still no leaks in my case.

Thoughts? Worry? Keep an eye out for?

My old Elantra would do the same thing. Stink like coolant once it made a few runs. Never ran low, never had a leak. But the coolant res tank was right up front when you openedthe hood. My guess was it was fresh and hot from the engine and the act of opening hte hood made the smell come to your nose.

I've had a few times with the Jeep where I've managed to lose coolant out of the overflow bottle with no obvious explanation. Turns out, it was sloshing up and out through the overflow tube when either tilted enough off-road or being sloshed around hard enough.

Keeping the reservoir a bit less full (just a little above where it'll complain about being low when the engine is cold) fixes the issue, as it can't slosh up high enough.

I've periodically had coolant leaks that were a bitch to find. The most recent was a water pump on my 4Runner that I didn't know until the dealer changed it during the timing belt change.

white stains on the rad?

Oh, and F spring clamps.

Bobzilla wrote: Oh, and F spring clamps.

Yep. They work great once or twice, but then they're worn out and need to be replaced (they'll never clamp tight enough again). Of course, worm clamps often need to be re-tightened when the weather gets cold if they were installed in the summer, otherwise they start to leak (exactly what the spring clamps try to prevent).

How carefully did you guys look for evidence of fluid around the overflow tank vent hole/tube/whatever? Sloshing out of there is entirely possible.

No smell inside the car ?

rslifkin wrote:

Bobzilla wrote: Oh, and F spring clamps.

Yep. They work great once or twice, but then they're worn out and need to be replaced (they'll never clamp tight enough again).

Use a spring clamp tool instead of a pair of pliers and they'll last indefinitely, or until they rust apart.

I converted my RX-7 to spring clamps. I love 'em. They simply don't leak. When I converted, I put used take-off clamps from junkyard engines and such, not new.

Pliers should only ever be used for plying, whatever that is, and what it isn't is hex nuts and spring clamps.

Pressure test the system, if it doesn't lose pressure cold and overnight it is probably good. My Mustang always smells like coolant when it is hot but it never loses any. Next time make sure it is at it's cold level before you go.

spitfirebill wrote: I've periodically had coolant leaks that were a bitch to find. The most recent was a water pump on my 4Runner that I didn't know until the dealer changed it during the timing belt change.

What year 4runner, my 04 has been doing this lately.

Knurled wrote:

rslifkin wrote:

Bobzilla wrote: Oh, and F spring clamps.

Yep. They work great once or twice, but then they're worn out and need to be replaced (they'll never clamp tight enough again).

Use a spring clamp tool instead of a pair of pliers and they'll last indefinitely, or until they rust apart. I converted my RX-7 to spring clamps. I love 'em. They simply don't leak. When I converted, I put used take-off clamps from junkyard engines and such, not new. Pliers should only ever be used for plying, whatever that is, and what it isn't is hex nuts and spring clamps.

Stock spring clamps on the Elantra and Accent leaked without ever being touched. Cat is having a similar issue with seepage under pressure as well. Hate hate hate spring clamps.

Yeah but that is because they inherited Mitubishi cooling system problems. If it is any consolation, I have an E36 328i in the shop right now with thermostat housing corrosion that is also leaking past the hoses... and they are worm clamp hoses. (Friggin' ALUMINUM parts, why couldn't they have made them from plastic? )

So I'll grant you that there is no mechanical idea so simple and perfect that Kia/Hyundai can't screw it up.

OldGray320i wrote: Hey all. The car is a 2012 Focus (base). At the autocross on Sunday, and after about 6 runs, back to back to back (my son and I, consecutive run groups, A then B), I noticed a coolant smell coming from the car - I popped the hood noticed the overflow coolant tank was pretty low (a little below min) and added a bit of water to it to get it to max. No leaks anywhere, no coolant dripping no matter where we looked. Figured some had just bled off over the course of 3-1/2 years. Let it cool with the hood up for a bit, closed hood did run number 7. After the run, popped hood, smelled coolant, and the overflow tanks was again lower than what i had filled at half again below min. Pulled the cap, and with the pressure relief got a rush of coolant back in the overflow - now at half again above min. I still had one more run, and my son and I both still had our time only runs (would've been another 9 runs total), but we canned them completely, no more autocross runs for the day. Worked my turn on the course, let the car cool with the hood up the entire time. No further loss of coolant, checked high and low for leaks, nothing, all hoses and connections with radiator circuit bone dry. No steam coming out the exhaust that we noticed, car ran fine, we went to lunch after the event - drove the car about 5 miles or so, got to the restaurant, popped the hood, no coolant smell, no leaks, etc.... We drove the 90 miles home, no issues to report, still no leaks, etc... Best I can figure, with all the runs back to back to back, we were running high temps, cooking the oil, over taxing the cooling system, and with the extra heat and pressure maybe it was "venting" past the hose connections (I think they call them constant pressure clamps?)? Still no leaks in my case. Thoughts? Worry? Keep an eye out for?

Coolant level will drop in the overflow when its hot, hoses bulge, stuff expands so takes more coolant to take up the space.

Check the level when cold. Checking the level is really only accurate when cold and should be done when cold.

Assuming there truly are no leaks(do a pressure test to check), I'm thinking when autocrossing coolant is splashing all around in the pressurizsd reservoir... When the cap vent at 20psi(or whatever its rated to), some coolant will undoubtedly be near/around the vent spot inside the bottle, as it vents it blows a bit of coolant out.

IIRC on those its a passage molded into the reservoir and vents along the backside/bottom?

Now one other thing I'll throw out because this happened on my Mazda3... I came in after a run and got the sweet smell and noticed stains on the exhaust manifold. I thought it was coolant at first(even smelled similar), but turned out to be the brake fluid cap leaking a bit I guess as pressure built up from fluid expansion? I wrapped a paper towel around the cap with a ziptie and never had a problem again with that.

Fueled by Caffeine wrote: white stains on the rad?

I need to inspect a little closer, now that the car is home...

iceracer wrote: No smell inside the car ?

Only from my soiled shorts when I was about to mow down 87 cones on a run...

flatlander937 wrote:

OldGray320i wrote: Hey all. The car is a 2012 Focus (base). At the autocross on Sunday, and after about 6 runs, back to back to back (my son and I, consecutive run groups, A then B), I noticed a coolant smell coming from the car - I popped the hood noticed the overflow coolant tank was pretty low (a little below min) and added a bit of water to it to get it to max. No leaks anywhere, no coolant dripping no matter where we looked. Figured some had just bled off over the course of 3-1/2 years. Let it cool with the hood up for a bit, closed hood did run number 7. After the run, popped hood, smelled coolant, and the overflow tanks was again lower than what i had filled at half again below min. Pulled the cap, and with the pressure relief got a rush of coolant back in the overflow - now at half again above min. I still had one more run, and my son and I both still had our time only runs (would've been another 9 runs total), but we canned them completely, no more autocross runs for the day. Worked my turn on the course, let the car cool with the hood up the entire time. No further loss of coolant, checked high and low for leaks, nothing, all hoses and connections with radiator circuit bone dry. No steam coming out the exhaust that we noticed, car ran fine, we went to lunch after the event - drove the car about 5 miles or so, got to the restaurant, popped the hood, no coolant smell, no leaks, etc.... We drove the 90 miles home, no issues to report, still no leaks, etc... Best I can figure, with all the runs back to back to back, we were running high temps, cooking the oil, over taxing the cooling system, and with the extra heat and pressure maybe it was "venting" past the hose connections (I think they call them constant pressure clamps?)? Still no leaks in my case. Thoughts? Worry? Keep an eye out for?

Coolant level will drop in the overflow when its hot, hoses bulge, stuff expands so takes more coolant to take up the space. Check the level when cold. Checking the level is really only accurate when cold and should be done when cold. Assuming there truly are no leaks(do a pressure test to check), I'm thinking when autocrossing coolant is splashing all around in the pressurizsd reservoir... When the cap vent at 20psi(or whatever its rated to), some coolant will undoubtedly be near/around the vent spot inside the bottle, as it vents it blows a bit of coolant out. IIRC on those its a passage molded into the reservoir and vents along the backside/bottom? Now one other thing I'll throw out because this happened on my Mazda3... I came in after a run and got the sweet smell and noticed stains on the exhaust manifold. I thought it was coolant at first(even smelled similar), but turned out to be the brake fluid cap leaking a bit I guess as pressure built up from fluid expansion? I wrapped a paper towel around the cap with a ziptie and never had a problem again with that.

I'll check coolant level tomorrow morning, haven't checked it since we got home - and drove the Miata this morning.

Pressure test is next, just to see - I think the vent spot is probably most likely, I've just not experienced it before with this car. I'll be checking for evidence of that tomorrow as well.

And, what are the F spring clamps that Bobzilla speaks of? I am not familiar with that/those. Unless it's them new fangled hose clamps...

I've seen a couple Focii (like 2 out of hundreds) of that generation sweat from the radiator seams, it's pretty hard too see without being under the car.

My '06 Mini does similar. On mine I know it's pressure leaking past the stupid screw on cap that is known to fail. It never needs any fluid but you do get the smell after being run hard.

Does it have the cap on the radiator or the tank ? If the tank is cap less it could be just venting. if the cap is on the tank, maybe a new cap is in order.

If you can smell it there is a leak... somewhere. Pressure test and let the car sit overnight under pressure. Keep pressure around one bar or whatever it is on the rad cap. (Just swapped a radiator that had the smallest pinhole been smelling coolant for like a year now... )Also change the radiator cap and maybe get rid of silicone hoses if you have them. If you dont see a leak after all of that check for wet spots under the heater core too

The wagon just failed a heater core in the same way. High rpm apparently was pressurizing the core and causing it to leak, but only over about 3k rpm. It always smelled a little and very slowly lost coolant, but I couldn't figure out why until the core failed catastrophically one day. Now, no more leaks, and no more smell. But I wouldn't expect the core on a 2012 to fail.