Blow out the carbon?

I have a 98 Accord with a 4 cyl, and the car is driven in city streets.
Is it still ok to take it out on the highway and run it hard, like we did
the old v8's, to blow out the carbon. This is my first 4 cyl and I wonder
whether it was still
necessary to do that?

Thanks,
Andy

 

Why not? You don't even need to take it to high speed, simply
run the RPM's up in a lower gear for a while.



mike hunt

 

I don't think the car needs it, but it's more fun to think it does

 

Yes, I "blow out the carbon" each and every time I enter the freeway.
It is always warmed up by that point, and what doesn't kill it will make
it stronger.

dan

 

Blowing out the carbon ceased to be necessary when they switched to unleaded
fuel. That being said, I still do it whenever I get the chance, just 'cause
its fun.

 

not to pick on *you* directly, mainly i needed to put my opinion out there
for the world to see. :~)>

there has NEVER been a reason to blow out the carbon on any engine. if it
is tuned right, it will never have any carbon to deal with! this is true
from the ancient in-the-block-valve technology of my lawnmower right up to
the I-VTEC technology of my honda. carbon is an symptom of a problem
elsewhere. mixture too rich, engine never up to operating temperature, etc.

oh yeah, since i brought up the briggs & stratton engine, ever notice the
spark plug on your mower just loaded with carbon? yes, they set them things
up at the factory to be extremely rich. how do you blow the carbon out of
it? :~)>
they are set rich so that they run cooler (ever notice your mower seems to
cut better when it is cold outside?) a lean briggs on a 95 degree (F) day
will melt in no time!

my wife would never buy the 'blow the carbon out' trick...

 

--snip--< carbon is an symptom of a problem --snip--<

carbon is A symptom of a problem

I HATE THAT!!! i should learn to proofread before i hit the GO pedal.
:~)>

 

You obviously never owned a '55 Oldsmobile back in the days of leaded gas.
Two weeks of city stop-n-go driving in that car and you were lucky if 6 of 8
cylinders still fired. The '63 was no better. I used to enjoy watching the
local cops floor the '66 Dodge patrol cars at each traffic light to try to
blow them out. But all that ended in the early '70s when the switch was
made to unleaded gas. No more lead deposits in the cylinders.

I agree with you now. Modern engines (using unleaded gas) do not build up
carbon deposits anymore unless they are seriously out of whack.

 

bob,
While I agree with your statement about the current crop of computer
contolled fuel mixture engines on cars, Briggs and Stratton engines
do have carbon buildup problems on most of their engines because most are
flathead designs, not ohv. (Honda stopped importing flatheads into the
US about 1984 except for one very small engine.)
Flatheads have carbon buildup because of excessively large quench areas
and crevice volumes,
something an ohv angine was designed to minimise, even before emissions
reductions were one of the major design targets of new engines.
As to the carbon buildup in your Briggs and Stratton engine, and also
for all flathead engines, there is generally a recommendation in your owner's
manual to periodically remove the heads and scrape out carbon deposits or remove
with chemicals run through the engine as it is operating . Onan has such chemicals
in spray cans, and having done this once and seeing and smelling what came out
of the engine, I will never do that again!
Large flathead engines especially in generators will not produce full power
if not decarboned every 250-400 hours depending on load and type of oil used.
If the engine in your car does not get up to full operating temp and at
that time is not loaded to about 85% or more of the full power it can
develop, it would help to get it into that target zone to help keep it clean
just dont wait too long and do it suddenly or you can fuse the loose deposits
onto the plug insulators, glazing them. A better method is to take your car
onto a little travelled highway and gradually increase speed to bring
up combustion chamber temperatures slowly.
Unless your car is almost never driven on the highway at all, this is not necessary .
Most people drive on the freeway enough to do this anyway.

 

you are totally wrong and seem to know nothing of what you are talking
about, basing all of your comments on "urban legend"

Lead in gasoline has nothing to do with "black smoke" that comes out of a
car. Black smoke comming out of a car is poorly combusted gasoline, due to
an over rich mixture. This is a carburator problem, and has completely
dissappeard (will 99.9%) with EFI.

Lead in gasoline is actually MUCH BETTER for ALL ENGINES because it was the
lead that had a propensity to deposit on the intake/exhaust valves (not in
the cylinder/pistons because temps too hot), you were basically assured a
lifetime of properly seating (soft) valves. When the switch from lead was
made we went to (hard) valves which now must be adjusted and their seats
replaced eventaully. The ONLY reason we switched from lead gasoline was
because the content of lead in the soil of highly populated areas was rising
signicantly as the automobile #'s in the U.S. skyrocketed in the
40's/50's/60's.

 

Urban legend my ass. I owned those cars and that is how they worked. And
all the other cars subjected to city driving worked that way as well. What
is your experience?

Yes. The switch away from leaded gas was for the purpose of reducing lead
in the atmosphere. It was just a nice side effect that once the lead was
gone and the cars were redone to run on the unleaded stuff, the bi-weekly
blow-out was no longer necessary. I'm sure they didn't plan it that way.

 

Hmmm, maybe... EFI can go wrong as well but, yes, the black smoke is poor
combustion.

While there had been pressure on the refiners to reduce lead content for a
while, the first and primary reason we went lead-free was because it
wrecked the catalytic converters. As for lead being better, there
certainly was more deposits in every part of the combustion chambers,
including piston crowns, with lead. That engines were cleaner on no-lead
was known long before we went lead-free, due to Amoco's lead-free gasoline,
which preceded the regulations by a number of years. A de-coke did not
involve removal of carbon alone - it was the lead which caused the
deposits.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??