Dale, The Kohler manuals from 1961 have had MANY revisions to get to the editions that you are quoting from.
In another thread you posted this:
Quote:
Originally Posted by Merk
All small engines were designed to run on unleaded fuel. A good example is a Cub Cadet Orginal. They were made early 60's.....long before unleaded fuel was the only fuel you could buy.
Interresting information on tetraethyl lead:
http://en.wikipedia.org/wiki/Tetraethyllead
I didn't see anything about tetraethyl lead being a lubricant.
Not knowing the history of the engine we can't tell what caused the problem(s).
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The engine in the Originals, were designed/built long before the implementation of 'unleaded' gasoline, or gas blended with ethanol, just like you said. I guess I don't understand how a Kohler engineer would design an engine to run on a fuel that was yet to be invented/created, let alone mandated/widely available, etc for at least another 12+ years.....
You also posted this:
Quote:
Originally Posted by Merk
Interresting....... 
Why does Kohler want the owner to use unleaded fuel?
Page 1.5 of a Kohler service manual states Use only clean, fresh, unleaded gasoline with a octane rating of 87 or higher.
Unleaded gasoline is recomended as it leaves less combustion chamber deposits.
The lead in gasoline acts as a cushion between the valve and valve seat. Some engines needed the lead because they didn't have a harden valve or valve seat. Leaded gasoline will leave deposits in the combustion chamber and valve stem. The deposits is what causes the valve to stick....not the lack of lube. |
If your other statement was true 'the engine in an Original was designed to run on unleaded gasoline', and that engine was fed leaded gas until the unleaded was made available 10 years or so later....the combustion chambers and valve stems would be a total mess, and the valves would already be stuck.
As you know, many folks have had issues with 'old' Kohlers and sticking/stuck exhaust valves, and you even suggested using MMO. If those older engines were already designed to be run on unleaded, there should be no sticking/stuck valve issues! And, there would be no need for an 'upper lube'!
From 'Wikipedia' at this address=
http://en.wikipedia.org/wiki/Gasoline
Tetraethyl leadGasoline, when used in high-compression internal combustion engines, has a tendency to autoignite (detonate) causing damaging "engine knocking" (also called "pinging" or "pinking") noise. Early research into this effect was led by A.H. Gibson and Harry Ricardo in England and Thomas Midgley and Thomas Boyd in the more powerful, higher compression engines. The most popular additive was tetra-ethyl lead. With the discovery of the extent of environmental and health damage caused by the lead, however, and the incompatibility of lead with catalytic converters found on virtually all newly sold US automobiles since 1975, this practice began to wane (encouraged by many governments introducing differential tax rates) in the 1980s. In the US, where lead had been blended with gasoline (primarily to boost octane levels) since the early 1920s,
standards to phase out leaded gasoline were first implemented in 1973 — due in great part to studies conducted by Philip J. Landrigan. In 1995, leaded fuel accounted for only 0.6% of total gasoline sales and less than 2000 short tons (1814 t) of lead per year. From 1 January 1996, the Clean Air Act banned the sale of leaded fuel for use in on-road vehicles. Possession and use of leaded gasoline in a regular on-road vehicle now carries a maximum $10,000 fine in the US. However, fuel containing lead may continue to be sold for off-road uses, including aircraft, racing cars, farm equipment, and marine engines.[6] Similar bans in other countries have resulted in lowering levels of lead in people's bloodstreams.[7][8]
Yet more info on lead in gasoline, from this address:
http://boards.straightdope.com/sdmb/.../t-301632.html
In 1987, I was told in my mechanics training that the leaded gas sold had virtually no tetraethyl lead. Leaded gas was completely phased out at the end of that year. If any pump gas in the U.S. has lead in it then it was added in violation of EPA regulations. More likely, the owner just never bothered with replacing the sticker on the pump.
Lead was added to gasoline for two reasons, to reduce detonation (http://www.progl.com/General/detonation.htm) (i.e. to increase octane) and to protect the engines' exhaust valves.
As the exhaust valves of an engine open and close, they're alternately heated by the exhaust gases that blow past and then pressed against the iron of the heads. The valves in older engines were made of untreated steel and the heads were iron alloy. Without tetraethyl lead, the valves would weld themselves to the head much in the same way that a blacksmith welds steel by heating it in a furnace then hammering it together. Over time this destroys the valves and seating areas. Lead was added to gas to perform a chemical vapor deposition. The lead is vaporized during combustion, is deposited on the valves, and the softer lead creates a barrier layer that keeps the valves and head from bonding together..
Lead in pump gas was phased out for two reasons. First, lead was released into the general environment. Second, besides coating the exhaust valves the lead also coated the pellets in catalytic convertors and (in later models of cars) it coated oxygen sensors, so not only was lead sent out the tailpipe, the emissions controls in a car were destroyed.
Other additives have replaced lead as octane enhancers (I think that MTBE has been banned as well.) The exhaust valves and seats are now made out of harder materials.
'ol George was/is correct