My car is a 2003 Buick Century and it has been leaking for the past few months (puddles of coolant under the car).

Now the car begins to have white smoke coming from the engine and it has a sweet smell so I'm sure it is coolant.

A few days ago I topped off my coolant and filled a little into the reservoir tank.

The very next day I saw the white smoke and my reservoir tank was empty. I removed the upper radiator hose yesterday to see coolant sitting in the radiator, this means it is clogged right?

I checked both hoses and I see no leaks/holes/ anyware, I still may take it somewhere for a pressure test.

I ordered a new radiator and I'm going to install it once it arrives. My radiator cap is fine as well and I'm sure my thermostat and water pump are ok but I could of course be wrong.

Also ,the car does not overheat as the white smoke comes out, it hasn't overheated at all in fact. The gauge stay in the middle and gets lower as I drive.

I've been driving it sadly because I have to get to work but yesterday and today not as much. White smoke was coming from the engine as before. The smoke is coming from the upper radiator hose and that is where it seems to be clogged at.

Any idea on the the problem?

  • Have you checked the oil to see if it is like chocolate milk? Commented Apr 3, 2016 at 22:12
  • yes , my coolant is not mixed with oil. Commented Apr 3, 2016 at 22:16
  • How do you know the water pump and thermostat are ok? What tests did you do?
    – cdunn
    Commented Apr 4, 2016 at 2:19
  • Are you able to take a look under the hood when it starts smoking to see where the smoke is coming from?
    – rpmerf
    Commented Apr 4, 2016 at 11:15
  • @rpmerf " the smoke is coming from the upper radiator hose " Commented Apr 4, 2016 at 19:35

2 Answers 2


Your problem is most likely a leak from the head gasket into a cylinder. The head gaskets are made with just a small separation between the place where the coolant flows (to prevent hot spots) and the cylinder so that the head gasket fails with small leaks. The head gasket is able to withstand the pressure of the expanding gasses for the moment that they affect the seal, but the intake sucks the pressurized coolant into the cylinder on intake and it is mixed and burned with the sweet smell of burning coolant. Burning coolant also gives off white smoke and it doesn't take much coolant to make it appear.

There would be no overheating early on, but there soon will be as the head gasket fails. You might try some kind of sealant like Bars Leak to postpone the inevitable repair. Perhaps you will get lucky and it will work for a long time - Buick engines are pretty tough.

I have successfully used a stop leak even on diesels, but the success has been marginal at best. GM recommends a tabular form of stop leak for its Vortec engines which I have used successfully and highly recommend. However, they recommend it for external head gasket leaks that plague those engines, not for the type of leak that I believe that you are experiencing. Auto supply stores will know what GM's recommended stop leak is called - you use one tab per gallon of engine coolant and an 8.1 liter Vortec requires six tabs (one package) so the Century engine should be probably 3 tabs. These tabs are not expensive and could give you a little time to decide what to do - if it doesn't work, you have some other method by which coolant is getting into the intake - and there are a few.


This was asked over 2 years ago, I presume the problem is solved now? You say the white smoke is coming from under the hood, correct? Not the exhaust? Sounds like a pin hole in the hose.

I had the same issue with my 2000 Pontiac Montana, it was using coolant, with no visible leak. Occasionally I would see white smoke coming up from under the hood, when I stopped and looked, nothing was there. I finally determined the leak was more noticeable after a hard acceleration. I did that up a steep hill, and stopped immediately. Saw coolant dripping out from back of engine, saw a tiny leak squirting out of the coolant hose quick release fitting top of motor, back of engine compartment. The torque from acceleration moved the motor so the leak would open up more.

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