Mysterious loss of coolant. Heat exchanger going bad?

[Bolivianfuego]

I have a stock 2010 S4 with 97K on the clock.

LOVE the car, and had the PCV, Thermostat, Supercharger (serviced), and new heavy duty water pump installed at 95K.


With the car cold, I popped the hood and noticed it was slightly below minimum (coolant). I put a splash of the G13 coolant to get it above the min line.

Could that be the heat exchanger going bad? I heard of potential coolant loss if the PCV went bad or the heat exchanger. Any help/insight would be greatly appreciated!

[shortyolsen2017]

Air in the system, intercooler leaking?

If pcv was done I can't imagine thats it.

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[hunter_killer]

I just went through the same scenario. Brand new PCV, thermostat, bled the system and what not. Began loosing coolant little by little. Replaced my intercoolers and the leak has gone away. This is my case but I’d say intercoolers are likely the culprit, if there’s no other external leaks.


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[Ford Prefect]

I have the same issue but no signs of intercoolers leaking. Plugs look good and no misfires.

I have a new PCV since I tercoolers are tough to come by. I also jury rigged a pressure test on the ICs. It held.


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[6SpeedS4]

I posted in another thread but had same issue. I finished waterpump, thermostat, pvc and carbon clean. I vacuum filled the coolant. About 90 miles later I'm down from max to min (car cold). Checked everywhere for a leak and found nothing, car ran fantastic, no codes.

Topped off the coolant and went for a 60 mile drive. No coolant loss.

I thought for a minute I installed a bad pvc. Will report back if I lose anymore.

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[bladekiller]

Had issues with mysterious coolant loss too. After changing to MercHX, no more problems. Suspect it gotta do with existing hx or pipe leaks


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