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MECH1200
WHAT CAUSES LEAKS
• Causes of leakage–Worn or damaged seals–Worn or damaged gaskets–Worn or bent parts or shafts–Fasteners over tighten or too
loose–Wrong parts or gaskets–Nicks or burrs– Improper installation
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SEALS
• Purpose:• Keep the oil in and the dirt out • Separate fluids or cavities• Withstand different pressures
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SEALS
• Originally made from old felt & leather seal.
• Most seals are made of Nitrile.
• Special Seals are made of Viton, Silicone, Polyacrylics or chemical resistant materials.
MECH1200
SEALS
A. The flexible material component of the seal produces the lip. In this design there is only one lip, the primary sealing lip
B. The outer shell of the seal holds the seal in place.
C. The garter spring (found in most seal designs) is a coiled wire spring that provides a controlled radial load over time.
MECH1200
SEAL INSTALLATION
1. Install with lip (and garter spring) toward liquid.
2. Lubricate lip before installation.
3. Use sealant on the outside of steel seals.
4. Use a seal installer.
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GASKET
• A pliable material that is shaped and placed between two mating machined parts to form a seal.
• Purpose of a Gasket– To confine; gas, oil, water, vacuum or exhaust
– Seal out foreign objects such as dirt & water
– Must withstand heat, cold, pressure, erosion, corrosion, moisture and oil
MECH1200
GASKET MATERIALS
• Gasket Materials– synthetic rubber– cork-rubber– embossed steel (Corrugated)– paper
MECH1200
GASKET INSTALLATION
1. Use a quality gasket2. Use alcohol or brake cleaner on a clean
rag to wipe the oil off of the machined surface
3. The surface must be dry4. Apply a gasket sealing liquid if
recommended5. Tighten in steps6. Use the proper torque pattern when
tightening7. Torque to proper specs
MECH1200
Stuffing Box
• An assembly which is used to house a gland seal.
• It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements.
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O-Rings• O-rings come in several sizes the most
common standard sizes are 1/16, 3/32, 1/8, 3/16, 1/4
MECH1200
• O-Rings come in several shapes– O being the most common – D shape, – Square-ring – Modified X
• Challenger disaster
O-Rings
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• O-Rings also come in different types of material to ensure compatibility with the fluid being contained
O-Rings
MECH1200
USING SEALANTS
• Use proper sealant for application.• Do not use a sealant unless specified in
service manual or by gasket manufacturer.• Types of sealants
– Hard drying like 3M Weather-stripping or a glue to keep a gasket in place
– Aerobic (RTV) cures when exposed to air– Anaerobic cure after the components are put
together (Thread lockers)
MECH1200
Aerobic (RTV)
RTV - Room Temperature Vulcanizing– Called Silicone Sealant– Replaces most gaskets– Forms a rubber seal by
absorbing moisture in the air– Sets in about ten minutes.
Dries in about 2 hours fully cures in 24 hours.
– Cure times will vary with Temperature, Humidity, and size of the gap
MECH1200
Aerobic (RTV)
– Blue is the most common color but also comes in Black, gray, bronze,clear, red and white(white is for the bathroom)
MECH1200
Blue Thread lockers
• Medium Strength for all bolts ¼ or larger
• Able to Remove with hand tools• Prevents parts from loosening
from vibration• Protects threads from corrosion• Recommend for valve cover bolts,
rocker arm nuts, carburetor studs, motorcycle, jet skis snowmobiles etc.
• Applied BEFORE Assembly
Recommended