which they were removed. Ideally, the plugs should have brown
insulator deposits. Sooty black insulators indicate anything from
carburetion problems to major engine issues. Blistered white insulators
indicate overheating, or the mixture is too lean. A light yellow glaze on
the insulator indicates the car was running at low speeds for an extended
length of time and somebody suddenly jumped on the throttle.
If an assistant is handy, he or she can sit behind the wheel and operate
the starter. If an assistant is not available, the starter must be operated
from under the hood. Ford and Chrysler vehicles have relatively easy
access to the starter solenoid. The solenoid on General Motors vehicles,
especially those with V-8 engines, is more difficult to access.
Screw the gauge into the first cylinder and engage the starter with the
throttle wide open. Watch the first reading, as well as the final reading.
The first stroke should read in the neighborhood of 70 pounds. After four
or five revolutions of the engine, a final reading can be obtained, which
will generally be around 150 pounds. (Consult a repair or shop manual
for the specifications of the vehicle in question.) If it takes several
revolutions to reach 70 pounds, there is a problem, most probably a
burned or sticking valve. Continue with the remaining cylinders,
recording the information for each. After completing the test, you may
find cylinders with markedly low readings. In these cylinders, insert a
teaspoon of oil into the questioned cylinder and retest. If the reading(s)
markedly improve, this indicates a ring problem. Readings should not
vary more than 20 percent between the highest and lowest cylinder.
singke
(singke)
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