spanky1
Veteran Member
I have a 2001 TDI with ~340k miles. Recently, I've lost coolant, so I've had to occasionally add some. A few years back, I had to replace a cracked coolant reservoir, but didn't replace the cap at the same time.
I've recently noticed that when removing the cap after the car sits overnight, there is a vacuum on the tank/lid. Same process as a pressure cooker sealing, I assume. The center piece of the cap is always stuck in the opening of the tank, and I have to pull it out by hand, and pop it back onto the cap.
1-Is the vacuum created by the cooling of the coolant normal? Since this is a closed system, it seems normal.
2-What would be the symptoms of a faulty cap? Since it holds a vacuum, it obviously seals quite well.
The coolant leak is bothersome, and I wondered if the lid could cause any issues.
I've recently noticed that when removing the cap after the car sits overnight, there is a vacuum on the tank/lid. Same process as a pressure cooker sealing, I assume. The center piece of the cap is always stuck in the opening of the tank, and I have to pull it out by hand, and pop it back onto the cap.
1-Is the vacuum created by the cooling of the coolant normal? Since this is a closed system, it seems normal.
2-What would be the symptoms of a faulty cap? Since it holds a vacuum, it obviously seals quite well.
The coolant leak is bothersome, and I wondered if the lid could cause any issues.