Thick white exhaust smoke

Tiny
ANGELATRAIN95
  • MEMBER
  • 1999 MERCURY COUGAR
  • V6
  • AUTOMATIC
  • 141,000 MILES
I noticed when I was accelerating I had thick white smoke coming out of my exhaust and I’m unsure on why or what’s causing this.
Thursday, January 31st, 2019 AT 5:20 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,834 POSTS
White smoke from the exhaust is due to burning coolant in the engine, and most commonly that is caused by a leaking cylinder head gasket. One way to verify that is to add a small bottle of dark purple dye to the coolant, then check a day later with a black light. The dye will show up as a bright yellow stain. If you find that inside the tail pipe, suspect the head gaskets. You can buy the dye for the fluid being tested at any auto parts store, and those that rent or borrow tools should have a black light.

Your mechanic can also perform a chemical test at the radiator to check for this. It involves drawing air from the radiator, with the engine running, through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow. When coolant is leaking into the combustion chamber, exhaust gases also usually sneak into the cooling system, then that is detected with this test. You can usually borrow this tester too from an auto parts store, but they will make you buy your own bottle of test fluid. That's because it is rendered ineffective if it freezes or if it becomes contaminated with antifreeze. They don't want to risk borrowing the tester to you with contaminated fluid. That's why they made the last person buy their own bottle of fluid. Due to the cost of this fluid, it might be less expensive to just have your mechanic do the test. It only takes a few minutes.

Here's two guides that can shed more light on the causes and fixes for this problem:

https://www.2carpros.com/articles/excessive-smoke-coming-from-the-exhaust-pipe

https://www.2carpros.com/articles/head-gasket-blown-test
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Thursday, January 31st, 2019 AT 6:00 PM

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