Engine knock and smokes

2000 TOYOTA AVALON
258,000 MILES • 3.0L • V6 • 2WD • AUTOMATIC
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AVALON52
  • MEMBER
  • 2 POSTS
The car runs great. But sometimes, like once or twice a month, if the car is sitting in a drive through or a traffic light, it has a knocking sound coming from under the hood on the driver's side and blows out a huge White cloud of smoke from under the hood and tail pipe. When the car starts off it stops the knocking and smoking. The smoke has a smell of antifreeze but does not use any coolant. It only does it a few times a month. Rest of the time it runs fantastic. I just wonder if it might be a injector or a piston. I don't understand why it runs so well and has these episodes. Any light you can shine on this problem would be greatly appreciated. I love the car but some local mechanics I've asked about it don't know what it could be and their solution is to sell the car.
Nov 11, 2019 at 6:16 PM
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JACOBANDNICKOLAS
  • ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
Hi:

Honestly, it sounds like a head gasket issue. Coolant burns white when it gets into the combustion chamber. If enough is getting in there, it can be causing the knocking sound because coolant doesn't compress.

When checking the coolant level, make sure to check the radiator. Also, here is a link explaining how to test for a head gasket issue:

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know.

Joe
Nov 11, 2019 at 7:47 PM
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AVALON52
  • MEMBER
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I really appreciate your quick response. I will check tomorrow about the head gasket. Will let you know what I find out. Thanks again
Nov 11, 2019 at 8:03 PM
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JACOBANDNICKOLAS
  • ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
You are very welcome. Let me know. It's odd that you are seeing white smoke under the hood too, but anything is possible.

Take care,
Joe
Nov 11, 2019 at 8:16 PM
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