Follow up to 2001 Nissan Sentra Knocking

After my 2001 Nissan Sentra (four cylinder) with 85,000 miles 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 with grey/white smoke coming
out of the tailpipe at the same time. Here’s what was done recently:


1. Valve Cover replaced – smelling oil – smoke inside car
2. Oil Change.
3. Two weeks later problem occurs.
4. Added “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. above, there was a slight
improvement each time, but the problem still exists, so the following
was done:

I. Switched coils #’s 3 and 4.
II. Did compression test.
III. Checked injectors.
IV. Checked radiator for loss of coolant or milky appearance –
negative.
V. Checked oil for foaming or contamination – negative.
VI. Smelled exhaust – smelled normal.

THE PROBLEM STILL REMAINS!! However, car runs normal in neighborhood
driving, and no overheating. (Does this rule out a head gasket
problem?)

I would like to thank those who responded to my first post on this
issue.

Any further suggestions would be appreciated.

Larry

Meu amigo..
Every time I have had a problem in the past with noise like marbles,
it has been an extreme timing problem.

There is no science to what I have said. Just observation.\\

Sometimes these things are hard to find. best of luck

On Wed, 13 Apr 2011 17:02:36 -0700 (PDT), iconlarry
> wrote:

>After my 2001 Nissan Sentra (four cylinder) with 85,000 miles 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 with grey/white smoke coming
>out of the tailpipe at the same time. Here’s what was done recently:
>
>
>1. Valve Cover replaced – smelling oil – smoke inside car
>2. Oil Change.
>3. Two weeks later problem occurs.
>4. Added “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. above, there was a slight
>improvement each time, but the problem still exists, so the following
>was done:
>
>I. Switched coils #’s 3 and 4.
>II. Did compression test.
>III. Checked injectors.
>IV. Checked radiator for loss of coolant or milky appearance –
>negative.
>V. Checked oil for foaming or contamination – negative.
>VI. Smelled exhaust – smelled normal.
>
>THE PROBLEM STILL REMAINS!! However, car runs normal in neighborhood
>driving, and no overheating. (Does this rule out a head gasket
>problem?)
>
>I would like to thank those who responded to my first post on this
>issue.
>
>Any further suggestions would be appreciated.
>
>Larry
>

Beginning to sound like head gasket problem at cyl #3. White *smoke*
out tailpipe is vaporized coolant.

Also explains why you smell smoke in passenger compartment. OIL and
coolant may be getting into #3 combustion chamber when engine his in
high revolution speed and high engine temperature...opens *crack* in
gasket enough for contamination of fuel-air mix in cylinder.

Head gasket change is not the end of the world. You can buy the
gasket(s) and do the job yourself if you have the right tools.

See Internet for "how to change engine head gasket." It's mostly time
consuming. If you have $$$ you can pay some mechanic to do the job
for you. Your call.

BTW, pressure leak down test should be done on cyl 3. How fast does
the pressure gauge fall after cylinder is at Top Dead Center.

Lg

iconlarry wrote:
> After my 2001 Nissan Sentra (four cylinder) with 85,000 miles 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 with grey/white smoke coming
> out of the tailpipe at the same time. Here’s what was done recently:
>
>
> 1. Valve Cover replaced – smelling oil – smoke inside car
> 2. Oil Change.
> 3. Two weeks later problem occurs.
> 4. Added “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. above, there was a slight
> improvement each time, but the problem still exists, so the following
> was done:
>
> I. Switched coils #’s 3 and 4.
> II. Did compression test.
> III. Checked injectors.
> IV. Checked radiator for loss of coolant or milky appearance –
> negative.
> V. Checked oil for foaming or contamination – negative.
> VI. Smelled exhaust – smelled normal.
>
> THE PROBLEM STILL REMAINS!! However, car runs normal in neighborhood
> driving, and no overheating. (Does this rule out a head gasket
> problem?)
>
> I would like to thank those who responded to my first post on this
> issue.
>
> Any further suggestions would be appreciated.
>
> Larry

I agree with Nicholas.
Do a leak down test and compression test on all 4.

On Wed, 13 Apr 2011 17:02:36 -0700 (PDT), iconlarry
> wrote:

>After my 2001 Nissan Sentra (four cylinder) with 85,000 miles 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 with grey/white smoke coming
>out of the tailpipe at the same time. Here’s what was done recently:
>
>
>1. Valve Cover replaced – smelling oil – smoke inside car
>2. Oil Change.
>3. Two weeks later problem occurs.
>4. Added “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. above, there was a slight
>improvement each time, but the problem still exists, so the following
>was done:
>
>I. Switched coils #’s 3 and 4.
>II. Did compression test.
>III. Checked injectors.
>IV. Checked radiator for loss of coolant or milky appearance –
>negative.
>V. Checked oil for foaming or contamination – negative.
>VI. Smelled exhaust – smelled normal.
>
>THE PROBLEM STILL REMAINS!! However, car runs normal in neighborhood
>driving, and no overheating. (Does this rule out a head gasket
>problem?)
>
>I would like to thank those who responded to my first post on this
>issue.
>
>Any further suggestions would be appreciated.
>
>Larry

Have you tried wide open throttle acceleration from a stop? Let us
know what happens.

You can also try swapping the #3 injector, and see if the miss follows
that injector. You say you checked them, but how? And have you pulled
all four plugs and compared their appearance?

If it really does run perfectly through moderate acceleration and
steady throttle, and you are losing no coolant at all, it sure sounds
like an injector. Also, oil getting into the combustion chamber lowers
the octane of the gas, and could cause a ping, but I can't think of
any reason that would happen only under load, but maybe the intake
valve is not opening all the way. Is there any ticking at idle,
especially one that comes and goes? (Is it a pushrod engine? I know
nothing about Nissans.)