2004 Audi A4 coolant

  • 2004 AUDI A4
  • 1.8L
  • 4 CYL
  • FWD
  • 96,578 MILES
I was running low on antifreeze so I got the green and put it in my car! I noticed the antifreeze wad orange before that and I've put green in every since. Could that hurt my car cause I notice it always needs antifreeze once a month and when I put it in, my rpms drop when I stop and my car dies. Its starts right back up. Also I notice its been smoking from under the hood and making a whistle/humming noise that kinda sounds like a siren at time but not as loud. What could this be. What do u recommend?
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have the same problem?
Sunday, October 19th, 2014 AT 4:42 AM

1 Reply

Recommend you stop ignoring all the warning signs before a minor problem turns expensive. Smoking from the engine coupled with regular coolant loss suggests there's a leak that could very likely be as simple as a loose hose clamp or as serious as a corroded cylinder head gasket. If the water pump is leaking and fails, repairs will be extremely expensive on any car. Repairs on Audis are usually double. On your engine the water pump is driven by the timing belt. Leakage usually occurs because the bearings are worn and they allow the shaft to move away from the seal. Once those bearings get bad enough, the timing belt will start to shred on one side until it breaks or falls off. Your engine is of the "interference" design meaning when the timing belt breaks, or even just jumps a few teeth, the open valves will be hit by the moving pistons as they coast to a stop, and they'll be bent. Replacing them requires removing the cylinder head, and that gets expensive.

At the mileage you listed the timing belt should have already been replaced as standard preventive maintenance. All conscientious mechanics who have your best interest at heart will want to replace the water pump too to insure the quality of the repair. If that work was done recently, it's likely your leak is less serious.

The first step is to determine the location of the leak. If you can't tell that by watching where the steam is coming from, a pressure test likely won't help either. Instead, add a small bottle of dark purple dye to the coolant, then search a day or two later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. Auto parts stores will have the dye, and those that rent or borrow tools will usually have a black light.

Once repairs are completed, your mechanic will flush the cooling system and put the right coolant in. Some manufacturers have gone to special formulas to try to solve corrosion problems, so it's not exactly the antifreeze that's different; it's the additives in it. Some additives do not mix well with others so using the wrong antifreeze can render some of them ineffective, and in some cases they'll turn into mud that can clog the heater core and radiator, and prevent it from flowing freely.
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Sunday, October 19th, 2014 AT 7:30 PM

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