Why does my car smoke from the exhaust after coasting downhill when there is a build up of negative pressure?

10

Asked by Aug 31, 2017 at 04:59 PM about the 2007 Lexus GS 350 RWD

Question type: Maintenance & Repair

I own a 2007 Lexus GS350 with 185000 miles on it. It runs beautifully with a
great amount of power. Besides the smoke that billows out it runs like a
champ.
I usually avoid the clouds of smoke by dropping my transmission into Neutral
when coasting downhill then put it back into gear just when I am ready to
apply pressure to the accelerator. If I don't do this, it will blow out massive
amounts of smoke. I have taken it to a repair shop and they said the number
5 head gasket was leaking and it needed a valve seal job. $4500 later and it
still smokes. They did the same job twice and it still smokes. Now they turn
me away and say they are done working on my car, so I had to pursue legal
assistance. Does anyone have an idea of what the actual issue could be?

3 Answers

70,895

What color is the smoke? Blue is oil burning, grey is automatic transmission fluid, black is too much fuel, and white is water vapor. Are any of your fluids going low repeatedly? HTH. -Jim

Best Answer Mark helpful
10

I want to say it looks bluish white. Smells like oil burning. My oil maintenance light always comes on to change oil and low engine oil always comes on so I have to add oil often.

1 of 1 people found this helpful.
70,895

Definitely sounds like burning oil. If you're seeing the smoke at idle such as waiting for a traffic light or in line at a drive thru it's valve guide seals. If you are seeing the smoke while driving it's your piston rings. HTH. -Jim

1 of 1 people found this helpful.

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