MECH1200 SEALS, GASKETS & SEALANTS. MECH1200 WHAT CAUSES LEAKS Causes of leakage –Worn or damaged seals –Worn or damaged gaskets –Worn or bent parts or.

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SEALS, GASKETS & SEALANTS

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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• Originally made from old felt & leather seal.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.

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SEALS

Seals can be: 1. Spring-loaded2. Spring-less3. Single-lip4. Multi-lip

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SEALS

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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.

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Inspect the shaft that the seal rides on; it might be bent or damaged.

SEAL INSTALLATION

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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

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GASKET MATERIALS

• Gasket Materials– synthetic rubber– cork-rubber– embossed steel (Corrugated)– paper

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GASKET MATERIALS

cork-rubber

synthetic rubber

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embossed steel (Corrugated)

paper

GASKET MATERIALS

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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

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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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Stuffing Box

GASKET MATERIALNormally a

graphite impregnated woven rope

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Stuffing Box

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Stuffing Box

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Stuffing Box

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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

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• 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

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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)

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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

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Aerobic (RTV)

– Blue is the most common color but also comes in Black, gray, bronze,clear, red and white(white is for the bathroom)

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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

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Red Thread lockers

• High strength requires heat to remove

• Works well for studs and press fit

• Locks against heavy vibration

• Requires extra effort to remove or special tools like heat. Without heat part may shear before thread locker releases

• Applied BEFORE Assembly