Coolant leak after track day, normal? Suggestions?

[ChosenJuan]

Hey guys, I took the mustang to the track yesterday (road course, did 3 sessions) and after letting the car cool down, I just drove it home. I didn't experience anything out of the ordinary throughout my sessions, no overheating issues or warnings, no limp mode or anything, but after gassing up last night, when I started the car I heard a sort of "water sloshing/slushing" sound right behind the dash. I popped the hood and I see the coolant level a few inches below the minimum line (barely any in the tank).

I waited for the car to cool off and I topped it off with distilled water, and after driving home (about 15 minutes) I noticed it was another inch below the min line. Topped it off again and left it alone until this morning. I drove for around 20 minutes but the coolant level hasn't changed. I don't see any leaks under the car, and honestly everything seems normal, drives fine, temps are fine, CHT are fine and the needle seems to be right in the middle for temps.

Any suggestions on what to check before I just end up bringing it to the dealer? My buddy said he could smell some coolant last night, but we didn't see any obvious leaks and temps while driving seemed fine. I don't think it's normal to lose that much coolant during HPDE. If you guys have any suggestions on things I could try before heading over to the dealership that would be great, thanks!

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[Cobra Jet]

Check your passenger floor board under the carpet and see if there is any coolant. A bad heater core will leak coolant within the HVAC box.

I have not heard of any heater core failures on the S550’s, but it’s not to say it can’t happen but it’s also a place to look.

Check all of your hoses - not just at the radiator, but also at the firewall where the heater core hoses are located.

Check the back side of the radiator for any coolant stains or leaks.

Tighten any hose clamps you come across.

Other than that, water pump failures have been brought up in the 5.0 section on this site for pre a thread failure. Look for any coolant seepage ant e water pump or on front of engine or under it.

Head gasket would be last place to research.

 

[ChosenJuan]

Check your passenger floor board under the carpet and see if there is any coolant. A bad heater core will leak coolant within the HVAC box.

I have not heard of any heater core failures on the S550’s, but it’s not to say it can’t happen but it’s also a place to look.

Check all of your hoses - not just at the radiator, but also at the firewall where the heater core hoses are located.

Check the back side of the radiator for any coolant stains or leaks.

Tighten any hose clamps you come across.

Other than that, water pump failures have been brought up in the 5.0 section on this site for pre a thread failure. Look for any coolant seepage ant e water pump or on front of engine or under it.

Head gasket would be last place to research.

Thanks! I checked the carpet and it wasn't wet at all, and I didn't smell any coolant on the inside (I didn't pull the carpet back though). Ever since I topped off the coolant, I haven't heard that sloshing sound behind the dash when starting the car. I just got back from driving it hard for around 30 minutes, and the coolant level hasn't changed since I topped it off last, temps were fine, CHT I saw max of 205, needle was in the middle, slightly closer to cold side. I checked the hoses, at least the ones I could reach from above the engine bay, and everything seemed nice and tight, and I couldn't see any obvious coolant stains or leaks. My buddy did say he could still smell coolant, but besides that, I really don't know what else to try, I shouldn't be losing any coolant at all after a track day right? I guess next step is to take to the dealer and let them know what's going on?

 

[GT Pony]

The sloughing noise was air in the system. After you added and drove it around a few times, all the air got removed. If you can get under the car look for any signs of leakage (stains, clinging drops of coolant, etc). If it can be smelled you should be able to see signs someplace.

 

[local driver]

Why did you top off with water rather than the correct water/coolant mix?

 

[ChosenJuan]

Why did you top off with water rather than the correct water/coolant mix?

There should be nothing wrong topping off with distilled water. I didn't have a premix ready right away but distilled water was nearby. I dropped it off to the dealership this morning and they haven't touched it all day, so that's fun, rental car time.

 

[ChosenJuan]

Well, the tech at the dealer wasn't able to find the leak, he pressure tested it and everything seemed fine on his end. But he did smell coolant though, so he's going to leave it pressurized overnight and drive it in the morning. Hopefully it's nothing serious

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