Misfire in 4.3L vortec (cont.)

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JQuigs1977 - 23 Jan 2005 06:33 GMT

After looking things over, am also noticing a lot of water coming out of
the exhaust pipe and air bubbles on the dipstick. Is this a head gasket?
Or is it worse or (please say) better. Would this be the cause of my
misfire? I have also listened to the engine
closely and the right side cylinders seem to be making a tapping sound,
not too loud though, and the left side are pretty quiet, like normal.
PLEASE HELP!! Thank you to all of
you who have helped out so far.

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\ - 23 Jan 2005 07:33 GMT

> After looking things over, am also noticing a lot of water coming out of
> the exhaust pipe and air bubbles on the dipstick. Is this a head gasket?
[quoted text clipped - 4 lines]
> PLEASE HELP!! Thank you to all of
> you who have helped out so far.

Two words:

Compression Test.

This will either rule in or rule out a head gasket problem.

Doc

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shiden_kai - 23 Jan 2005 15:55 GMT

> After looking things over, am also noticing a lot of water coming out
> of the exhaust pipe and air bubbles on the dipstick. Is this a head
> gasket? Or is it worse or (please say) better.

You can't tell anything by these two items. A normal by product
of combustion is water....tons of it. If you feel like "tasting" the
water, you "might" be able to taste antifreeze if it's in there. The air
bubbles on the dipstick are also meaningless, perhaps you've
overfilled the oil?

Ian

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Meat Plow - 23 Jan 2005 18:50 GMT

antifreeze will smoke if it's being burned in the engine. If you're seeing
water, clear water, coming from the tail and not smoke, it's a byproduct
of combustion gasses and condensation inside the muffler and not an
indication of an instrusion of coolant into the cumbustion chamber. In any
event you need to perform a cylinder leakdown compression check just to
make sure. And the tapping sounds you hear may or may not be normal sounds
from the valve train. A skilled tech like myself can usually rule out any
abnormalities just from his or her experience in listening to a wide
variaty of engine noises. Case in point, I own a 2003 Trailblazer that
makes some valve train noise when it's really cold. I would consider this
normal. Same goes for my 2004 Vulcan motercycle's V-twin motor except it
makes more noise when it's hot. If it didn't make noise, the valve
clearance is too tight so some noise is expected depending on the design
of the motor.

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shiden_kai - 23 Jan 2005 21:00 GMT

> may or may not be normal sounds from the valve train. A skilled tech
> like myself can usually rule out any abnormalities just from his or
> her experience in listening to a wide variety of engine noises. Case
> in point, I own a 2003 Trailblazer that makes some valve train noise
> when it's really cold. I would consider this normal.

If it's the inline 6 cylinder engine, it's highly unlikely that you
are hearing valve train noise. These engines will make noise
when cold, but although it might sound like valve train noise,
it's the piston making the noise. Same with all the other GM
engines that have "piston slap".....everybody assumes it's a
valve train noise, when it's really coming from the piston.

Ian

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Santa - 23 Jan 2005 19:39 GMT

> After looking things over, am also noticing a lot of water coming out of
> the exhaust pipe

and air bubbles on the dipstick.
Cat Converter is Pluggin up..

Is this a head gasket?

> Or is it worse or (please say) better. Would this be the cause of my
> misfire? I have also listened to the engine
> closely and the right side cylinders seem to be making a tapping sound,
> not too loud though, and the left side are pretty quiet, like normal.
> PLEASE HELP!! Thank you to all of
> you who have helped out so far.

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JQuigs1977 - 24 Jan 2005 02:03 GMT

I ran the engine for about 20 seconds and went under to feel the pipes.
the drivers side exhaust pipe after the converter was warm and the
passenger side seemed quite a bit cooler. I know this may sound stupid,
but wouldn't that be a definate sign of a clogged cat converter? and
would that be causing the misfire?

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4645@mydeja.com - 27 Jan 2005 02:06 GMT

>I ran the engine for about 20 seconds and went under to feel the pipes.
>the drivers side exhaust pipe after the converter was warm and the
>passenger side seemed quite a bit cooler. I know this may sound stupid,
>but wouldn't that be a definate sign of a clogged cat converter? and
>would that be causing the misfire?

Had the same problem with my S-10, 2.8 V-6. Single exhaust. A clogged
converter will foul everything. No power. Little old ladies were passing
me, honking their horns.

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\ - 27 Jan 2005 02:15 GMT

>I ran the engine for about 20 seconds and went under to feel the pipes.
> the drivers side exhaust pipe after the converter was warm and the
> passenger side seemed quite a bit cooler. I know this may sound stupid,
> but wouldn't that be a definate sign of a clogged cat converter? and
> would that be causing the misfire?

One fellow suggests a clogged cat based on air bubbles on the dipstick
<where the f**k did that come from?> and you think it's the cat?

The fact that one was warm and the other was cooler could be indicitive of
one side running very lean, or one side running very rich. To rule out the
cats in one fell swoop, just disconnect the exhaust prior the the cats and
see if the problem goes away. If you did have a plugged cat it would likely
have set an 02 DTC on that bank anyhow.

Until you run a compression test and verify that everything is sound
mechanically you really can't do much of anything else. You still haven't
run a compression test have you? Pissing around on here guessing ain't
going to fix your truck, so get out the the garage and either run a
compression test or disconnect the exhaust pre-cat and see what
happens....................

Doc

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