Used to be a LOT of injector problems on 2.2 and 2.5 liter K-Cars with
TBI - and cleaning very often fixed them.
They didn't block up , they leaked. Get the gum out and the pintles
could seal properly when they closed, and the stumbling, smoking, and
assorted other problems dissapeard.
Used to have some prblems about the same time (early 80s) with bosch
L-Jetronic based systems too, where the injectors would dribble. A can
of BG 44K usually fixed them up if you caught them soon enough.
Some brands of gas were better than others.
That's all a crock. If you use gasoline equipment every year there
should be no problem. I never have gas or starting problems ever.
It takes more than a year for gas to go bad and gum things up. I even
start and warm up things in off season to keep them good.
I agree. A year ago I forgot to run the snowblower dry and since I
normally do, it didn't have any stabilizer either. Come winter, it
wiould not start. I wound up having to pull the carb, buy a rebuild
kit and clean it. No question there were gum deposits inside which
were the problem. After that, it started right up. So, with about
13 years of experience with no problems, having it gum up the one year
gas was left in it is evidence to me that it's not a crock.
I drain the snowblower and add sta-bil to the lawn mower.
the modern engines are designed for 87 octane unleaded. Stabil in the
tank if it's gonna sit over a year is a good idea. If less than a year,
don't worry about it.
sounds like you were talking to an old timer that didn't know shit.
Well-seasoned? To me that says old, and old gas is the stuff that
varnished up your carburetor...
If the first two are throwing you for a loop, push the mower out to
the side of the road now and put a sign on it that says "FREE." Then
hire your lawn mowed by a professional... It's not difficult to push
the "92" button on the gas pump, or to follow the directions on the
Sta-Bil bottle. You can buy Sta-Bil practically anywhere...
92 octane doesn't hurt. It doesn't help, but it doesn't hurt. The Sta-
Bil is a proven product that keeps your gas from going sour by sitting
around for many months.
Lead additive... That's snake oil. Even if you can find lead additive
and it does do something, your mower doesn't need it unless it is
really really old. Truth is lead additive doesn't do anything, and
nobody sells it.
On Thu, 12 Nov 2009 15:51:09 -0800 (PST), firstname.lastname@example.org
Lead was a way of acheiving higher octane (resistance to knocking).
High compression engines will knock with too low octane, but maybe
that is lessened with fuel injection (just a guess), or with a
different spark timing, or maybe cars don't come with 10.5:1
compression ratios anymore.
They've even lowered the octane of gas with the same octane number.
About 20 years ago I think. 92 octane used to mean one thing, but now
92 octane is the same as 89** octane used to be
**not sure of the number.
So no he doesn't need it, but it used to be important.
The octane ratings have not really changed - in North America anyway,
it's always been R+M/2 (reaserch octane plus Motor octane devided by
two) for automotive gsoline.
Aircraft gasoline is totally different - with the two numbers, say
85/90 being rich/lean ratings.. The aviation lean motor rating is
close to the automotive R+M/2 octane in most cases.
RON, or research octane number, is a mostly theoretical number,
comparing a sample of fuel to a standard mixture of "octane" and
"heptane". The MON, or Motor Octane Number, is measured knock
resistance using a standardized variable compression engine in a
closely controlled load test to detect actual knock resistance under
load in an engine.
In many parts of the world the RON was (and still is) used - In North
America the R+M/2 or "road octane" rating has been used since the late
30s or early 40s.
On Fri, 13 Nov 2009 01:59:06 -0500, email@example.com wrote:
I read what you have below, but I know I was told something like my
paragraph just above. Maybe even heard it on the radio. I googled a
bit now and can't find anything to support my statement, however. Do
you or anyone know what I could be thinking of? Was it a hoax? Does
anyone remember it?
On Fri, 13 Nov 2009 06:38:08 -0500, firstname.lastname@example.org wrote:
Well, I have several (4) decades of experience as a mechanic that
re-enforces what I have been taught - high octane fuel will NOT damage
an engine. High LEAD fuel can damage an engine. High lead fuel is high
octane, but high octane does NOT need to be high lead.
Propane is 115 minimum AKI and unless it is run too lean it will NOT
harm an engine (if the engine has hardened valve seats designed for
High octane unleaded motor fuel without ethanol likewise will not harm
any engine designed to run on regular unleaded gasoline.
Well, for openers I didn't say any engines were destroyed. So now who
is making things up and talking out of their ass?
octane = burn retardant
it slows the bang down for a more even, cooler burn
thats how higher octane 'cures' pinging - by burning cooler and calmer
"Cooler" also promotes carbon buildup in engines that are designed to
run on lower octane gasoline.
You need to understand the difference between detonation and
pre-ignition. Pre-ignition is ignition instigated BEFORE the spark
fires - generally from a hot spot in the cyl. This can be a sharp
valve edge, glowing carbon, overheated spark plug, etc.
THAT is not detonation, and higher octane fuel will NOT prevent, or
even reduce it.
Detonation is the "explosion" of the destabilised end gasses, usually
farthest from the spark plug, in static pockets, due to high heat and
pressure causing the hydrocarbons to dis-associate.
Octane rating indicates the ability to resist this spontaneous,
uncontrolled burning after ignition has occurred., and a faster
burning fuel is less likely to detonate than a slow burning fuel
(natural octane, I like to call it) This is also why detonation
GENERALLY occurs at lower speeds and under high load, not at higher
Detonation can CAUSE pre-ignition, but is not detonation.
Detonation can also CAUSE pre-ignition. If cyl head temperature
increases and exhaust gas temperature drops, that is the surest sigh
that detonation has occured,
How, or why, you may well ask?
When detonation accurs, it disturbs the layer of air directly against
the surface of the combustion chamber, and "scrubs" it off. This layer
acts as an insulator, preventing the total heat of combustion from
being transfereed to the cyl head and piston. Whenit is disturbed,
much of the heat of the exhaust is absorbed bu the piston and cyl
head, reducing the exhaust gas temperature and raising the cyl head
Now, when this happens, parts of the cyl head and/or piston, and/or
the spark plug, will overheat, and there becomes a high probability
that the fresh charge of air/fuel mix will ignite spontaneously before
the plug fires - classic pre-ignition.
If pre-ignition happens as a precursor to detonation, it is because
the spark, occuring too early in the cycle, causes cyl pressures to
increase MUCH higher than normal (expansion against a rising piston
instead of against a descending piston) and that pressure and heat
acts on the end gasses for a longer time, making the disassosiation
and detonation more likely.
Pre-ignition causes a normal, controlled conflargation in the cyl -
just at the wrong time. Gives you the same effect as "spark knock"
caused by over-advanced timing - which again is NOT detonation - but
can cause detonation.
Pre-ignition and "spark knock" can be hard on bearings and pistons -
causing causing cracked or broken pistons and/or pounded out bearings
and/or bent rods etc.
Detonation, on the other hand, causes burned pistons and/or metal
transfer to the spark plug, and/or cratered surfaces in the combustion
chamber (looks like small sharp bits have been pecking away at the
roof of the combustion chamber, or the top of the piston ) and
aluminum "spray" on the plug tip, and CAN cause fractured pistons,
damaged bearings, bent rods, etc along with the other signs of
Detonation causes overheating as well as being excaberated by
Pre-ignition is most often caused BY overheating.
Detonation as a precursor to pre-ignition is more common than the
other way, but both are possible.
On Fri, 13 Nov 2009 18:15:15 -0500, email@example.com wrote:
Wrong. Dead, completely wrong. Running High Octane gasoline in a low
compression engine that is not designed for it will cause excessive
carbon buildup which can lead to frozen and broken rings, cylinder
scoring. The carbon buildup can also lead to pre-ignition which can
trash the engine, too.
Your 4 decades didn't teach you much.
On Fri, 13 Nov 2009 22:02:39 -0500, firstname.lastname@example.org wrote:
Running too rich or too cold causes carbon build up. Running fuel with
too much lead causes lead buildup.
Running high OCTANE fuel causes NEITHER.
There is more MYTH surrounding fuel octane and the results of using
octane higher than recommended for an engine than just about any other
automotive or engine topic today.
Much of it is based on half-truths.
A continental 85 aircraft engine, for instance, was designed to run on
80/87 octane aviation fuel (White) which had virtually no lead. It is
no longer universally available, so users are forced to use either
100LL (Blue) or 100/130 (green) gas. The Lycoming O200 is another
Using the highly leaded 100/130 will cause engine damage due to rapid
lead buildup - particularly on the valve stems. Using "blue" avgas,
100LL, is less problematic as it contains significantly less lead
(although still much higher than the old leaded super premium
automotive gas) and can be used on these older engines with some
caveats. Agressive leaning can be used to purge the lead, or certain
additives can be used to keep the lead from sticking and remove lead
that has accumulated (to a certain degree) Alcor TCP is one commonly
used additive for this purpose. TBO on these engines when run on the
highly leaded fuels is generally lower than it would be running
80/87, and Mogas STCs are available for many engines/planes to allow
the use of 87-92 (minimum) octane unleaded automotive fuel - with NO
ETHANOL. This is becoming more commonly available at many airports.
This is the basis for the MYTH that high octane fuel causes build-up
problems and engine damage.
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