Engine Knocking

Apr 10, 2011 5 Replies
I

After my 2001 Nissan Sentra (four cylinder) is warmed up and driven on the highway (especially uphill) car knocks ? (sounds like marbles hitting together) with loss of acceleration power, almost like car was going to stop. Also, on occasion, after adding ?Techron? saw white smoke out of tailpipe. Here?s what was done recently:


  1. Valve Cover replaced ? smelling oil ? smoke inside car
  2. Oil Change.
  3. Discovered problem.
  4. Put in ?Dry Gas.?
  5. Code reader showed #3 cylinder mis-firing.
  6. Changed spark plugs.
  7. Changed #3 coil
  8. Added ?Techron? to gas.


After applying #?s 4., 5., and 6., there was a slight improvement each time, but the problem still exists.



Any suggestions would be appreciated.



Larry


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N

Do you have a temp gauge? What does the coolant and oil look like?

Typically white smoke says burning water/antifreeze; I'm fearing blown head gasket, but hopefully I'm wrong.

nate

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I

Nate: Thank you for responding. Did u read what I added on-my husband forgot to mention some things. Temp guage normal, oil just changed 5 days prior to problem, husband checked and says oil is clear. Coolant is at minimum I showed that to my husband but he has not corrected. YOur mentioning reminded me. Also were two times when stopped for a light, that light knocking occured and lots of exhaust smoke, we thought maybe that was the Techtron, because it was within a few hours of putting in.

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P

How many miles? How much oil does it use? What did you expect the techron to do?

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2001 Nissan Sentra with 85,000 miles, gently used-timely oil changes. Oil use is normal, have changed oil at mileage mechanic posts in car, Techron was added after car still was knocking after plugs and cylinder # 3 coil was changed, to possibly clean out fuel injector- perhaps some dirt got in. Mechanics thoughts were I used a different reputable gas station to fill-up-thought maybe some bad gas, or station just had fill-up, and I purchased the gas? Right now just added coolant to bring to MAX, it was barely below min.
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I

Hi: I added coolant brought up from min to near max because of your asking. Thank you. My husband's take on problems were not exact. The computer reading (without any 'Check engine light" on) showed 2 codes. One for cylinder 3 and one for cylinder 4. After all plugs were changed, knocking problem persisted, so mechanic changed cylinder 3 coil because that code came up again. However, problem still persisted but milder. After test drive by me, with NO "check engine light" showing, but just blinking when problem occurs then stops, again the code for Cylinder 3 was there. Code for cylinder 4 is NOT showing. Mechanic baffled told me to just drive, but we are concerned about driving long distance, at night, etc. Want to fix problem because need reliable car. Thanks.

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