Hey crew,

2015 V6 S, 56K miles. Updated Y pipe. I realize coolant issues and their respective forum posts are nothing new. Yesterday, I did my usual weekly under hood fluid check. Found the coolant reservoir extremely low. Car has been parked since last week in same garage bay. When parked it was at MAX. No visible dampness on engine, no puddles under car. Bone dry.

Had to add nearly 40 OZ of coolant. Cap screwed on 5 clicks. Drive 43 miles. Park. Check. Has dropped to Min. No puddles under car.

Drive a different route back of 36 miles. Park & Check. It's now 4" BELOW "MIN" line! Can smell coolant, albeit faintly. Still, no puddles under the car.

Car operates at normal temp. No steam. Etc.

I realize this could be a myriad of things, but I'm just beyond perplexed how I can lose so much coolant and yet have absolutely zero visual clues in or under the car. Going in next week for the usual pressure test etc. But in the meantime...thoughts?

Thanks

 

Not at all uncommon for it to pool up in the valley between the heads.

 

Truth. But such a large amount without ANY sign underneath?

 

Possible. It can hold a decent amount of fluid, and a running engine can boil it off. You also have undertrays. Check the front of the motor too and see if the coolant pump has signs of leaking. Look for signs of dried coolant on front of the motor, bacl of the motor, and generally around the engine bay. You have the updated pipe which is good, but no guarantee. Another thought - check your overflow tank for leaks.

 

Did you check your belly pan, bet you will find some there.

 

When the Y pipe got changed did they pull the oil cooler and change that gasket? Did you get the new stupid little pipe that runs from the back of the WP to the oil cooler and it’s O rings?

Water pump and thermostat housing are also likely suspects, as others have said, the belly pan can hold a bunch of coolant.

Lastly, the reservoir its self and the overflow pipe.

 

Thank you for the insight. It goes in next Wednesday. I've located the general area it seems to be pooling on the under tray. It's a start.

 

With the engine cold, use a cooling system pressure tester to pressurise the system to 1 bar. If the pressure tester gauge begins to drop below 1 bar after 10 minutes, check for leaks.

The water outlet pipes under the front of the supercharger, and the heater pipe between the cylinder heads at the rear of the engine are known failure points. There are aftermarket aluminium water outlet pipes that can be used to replace the plastic pipes. There is also a recently designed aftermarket aluminium heater pipe that may be a good replacement for the plastic part.

 

Good advice in general but for the OP no point as the leak has already been established so no point reproving it.
Given it is a big leak maybe have it flat bedded to your dealer to avoid a catastrophic failure if you are thinking of driving it there.