2001 Audi S4 Question How can I tell if I need to replace my

Tiny
JMA5049
  • MEMBER
  • 2001 AUDI S4
  • 6 CYL
  • AWD
  • MANUAL
  • 125,000 MILES
My car has been leaking coolant for while now. I took it to a mechanic after it all flooded out at one tiime. He checked it out and replaced the auxiliary water pump and told me when I went to pick it up that it was possible it might need a new radiator because there was a small leak. Well by the next morning that small leak became a large leak and my coolant emptied all over the pavement all over again. My question is how can I tell if it really is the radiator that needs replaced? I don't want to replace things that aren't broken. The leak appears to be coming from the front of the engine which is where the radiator is. I appreciate any help with this.
Tuesday, June 15th, 2010 AT 6:04 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,916 POSTS
Hi jma5049. Welcome to the forum. There are two ways to find elusive leaks. For slow leaks, dye can be added to the coolant, then, after a few miles of driving, a black light is used to show up where the dye is coming from.

More commonly your mechanic will use a pressure tester to pressurize the cooling system up to its normal 15 pounds that it develops when the engine warms up. Leaks will be evident then as seepage or dripping onto the ground. It's a matter of searching for the source. You can develop the same pressure by starting with a full radiator, then warming up the engine. The heating and expanding coolant will build pressure that will push the coolant out of the leak.

If you're finding a really big puddle under the car, (big enough to reach both front tires), suspect a leak that is close to the bottom of the radiator or the lower hose. If you see steam when the engine is warm but not a very big puddle, that suggests the leak is up higher.

Caradiodoc
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Tuesday, June 15th, 2010 AT 7:25 PM

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