BHARATI VIDYAPEETH DEEMED UNIVERSITY

COLLEGE OF ENGINEERING, PUNE.

Department of Mechanical Engineering

SEMINAR REPORT ON

CYLINDER HEAD GASKETS

SUBMITTED BY:

MR. TUSHAR DHONDIRAM JADHAV

M.TECH SEMESTER III (MECHANICAL)

UNDER THE GUIDANCE OF:

PROF. D. G. KUMBHAR

(2012 – 2013)

1

BharatiVidyapeeth Deemed University

College of Engineering, Pune – 4110043

CERTIFICATEThis is to Certify that Mr. Tushar Dhondiram Jadhav have carried out a Seminar

report entitled on, “Cylinder Head Gaskets” in college is submitted by in partial

fulfillment of the requirements for the award of degree of Master of Technology in

Mechanical (CAD/CAM) course of Bharati Vidyapeeth Deemed University, College of

Engineering, Pune at college during academic year 2012-2013.

Date:

(Prof. D.G. Kumbhar) (Mr.V.K.Kurkute)

Guide PG Co-ordinator

Prof.Srinivasan Examiner Head of the Department

2

ACKNOWLEDGEMENT

First of all I thank the almighty for providing me with the strength and courage

to present the seminar.

I avail this opportunity to express my sincere gratitude towards

Prof. N. S. Sreenivasan, head of mechanical engineering department, for permitting

me to conduct the seminar. I also at the outset thank and express my profound

gratitude to my seminar guide Prof. D. G. Kumbhar and PG Co-ordinator Prof. V. K.

Kurkute, for their inspiring assistance, encouragement and useful guidance.

I am also indebted to all the teaching and non- teaching staff of the

department of mechanical engineering for their cooperation and suggestions, which

is the spirit behind this report. Last but not the least, I wish to express my sincere

thanks to all my friends for their goodwill and constructive ideas.

Mr.Tushar Dhondiram Jadhav

M. Tech. Mech. (CAD/CAM)

Sem – III

Examination Seat No. : 1211470002

3

Abstract

Gaskets are used to seal leakages between two joints. There has been great

research and development in the field of gasket in late 20 th century. Gasket

development started from simple asbestos sealing and now has reached the stage

where gaskets with multi metallic composition are used in large production.

Head cylinder gaskets have multiple functions bearing pressure, temperature

and do sealing for oil and coolant as well. Different head gaskets have been used

different time periods in the 20th century.

4

Index

Contents Page No.

1. Gasket an introduction 6

2. Cylinder Head gaskets 8

3. Head gasket – Time Zones 12

4. Head gasket – Combustion Sealing 18

5. Bibliography 28

5

Chapter 1

Gasket an Introduction

6

Chapter 1

Gasket an Introduction

Definition: “Any of wide variety of seals or packing’s used between matched

machine parts or round pipe joints to prevent the escape of gas of fluid.”

Flat Gasket for industry in the modern sense were invented by Austrian

engineer Richard Klinger about 100 years ago, based on asbestos and rubber. Due to

their success, these first products attracted numerous imitators, and soon many

materials of various qualities were available. The number of different sealing types

was considerably increased with the development of asbestos free gaskets

The important material properties for gasket materials are:

1. Loading capacity

2. Sealability

3. Elastic behaviour of a gaskets

4. Capacity for chemical resistance against media.

7

Chapter 2

Cylinder Head gasket

8

Chapter 2

Cylinder Head gasket

The tensile strength of a material, expressed by the breaking or tensile strength, is

not of particular importance for quality consideration, because no tensile forces are

usually exerted on gasket, only pressure forces cylinder head gasket

The cylinder head gasket is the most critical sealing application on ay engine.

Typically, it must simultaneously seal:

A. High combustion pressure and temperature

B. Mixture of water and anti- freeze, with its high wicking and wetting.

C. Lubricating oil, with its associated detergents, additives and variable

viscosities either built in or changed with season.

In addition, the head is structural component of engine, i.e. combustion chamber

is formed by the head,block, piston, piston ring and gasket. The gasket shares the

same strength requirements as the other combustion chamber components

The head gasket is used many times either to meter or to block coolant flow for

proper cooling of the engine. It also seals the block- liner intersection in wet liner

engine. Its compressed thickness effect the compression ratio of the engine, and

the importance of the compression ratio control to emission levels, specially in

diesel engines is well known.

Today’s engine manufactures require that the head gasket perform without a

rhetorical operation, seal for extensive periods of time, and “come off clean” so

no scraping of the mating flanges is necessary when the engine is repaired. The

head gasket sometimes needs very high thermal conductivity to transfer heat

efficiently between the block and head. It must be constructed so as to permit

rough handling and extended storage life. The gasket must also performin

temperature ranges well below freezing at start up to over 700 degree Fahrenheit

9

in the combustion seal area during engine operation. It must accept occasional

instances of detonation without failure. This is especially true today, when

premium fuel are sometimes un available and detonation associated with regular

or no lead gas occurs

The gasket must typically withstand combustion pressures of 1000psi in

naturally aspirated spark engines and 300 psi or higher in turbocharged diesel

engines. T0odays gasket must also accommodate greater motions, both thermal

and mechanical, because lighter weight casting and lighter- weight less rigid

materials are being utilized for cylinder heads and engine blocks. As a result of all

these requirements, the gasket is a verity complex product.

For head gasket to seal properly, the head bolts must apply a sufficient

clamping force on the gasket. As the bolts must apply sufficient clamping force on

the gasket. As the bolts are tightened, the gasket is squeezed to provide a seal

between the cylinder head and the engine block deck. Allgaskets relax a certain

amount. This is true even with “no torque” gaskets. The ideal no torque gasket

design compresses sufficiently at installation to conform to and seal minor

surface imperfections. At the same time, the design minimizes relaxation and

maintains adequate clamping force over a long period of time.

By contrast, a retorque designed will relax excessively. This reduces the

tension on the bolts and results in excessive torque loss. If one doesn’t

retorquethis type of gasket engine could lose compression and fluid or

combustion gas leakage will result. Leaking combustion gases can damage the

gasket surface or cause the blow out of an entire gasket section. Loss of coolant

could result in engine overheating leading to engine damage. In addition, a

retorque operation is costly. Any technician knows how time consuming engine

work has become. Tighter engine compartments and emission and electronic

controls make many engines extremely difficult to work on. With a retorque head

gasket, the head bolts typically need to be retorqued up to the engine has been

10

warmed and again after several hundred miles the time needs to gain access to

the head bolts for retorquing will quickly reduce the profit the technician makes

on the job. Also the vehicles owner is inconvenienced because the vehicle needs

to be returned to the facility for retorquing.

11

Chapter 3

Time Zones

12

Chapter 3

Head gaskets – Time Zones

1910-1930

Zone A: Initially, the basic head gaskets for engine were of the sandwich type, with

asbestos millboard centre and either tin- plate or copper on the outer surfaces.

Grommets and eyelets were incorporated in these gaskets, depending on the specific

engine needs. Numerous versions were designed and manufactured

1930- 1950

Zone B: As engines gained sophistication, gasket also gained in sophistication, and a

variety designs were produced. These designs utilized various reinforcements at the

combustion chamber seal for improved sealing. Metal shims and reinforced filler

materials, for example, were incorporated into many constructions

13

1950-1980

Zone C: The embossed steel shim gasket was the next popular gasket to be utilized

on passenger car engine. This gasket had a plastic resin coating applied for micro

sealing purposes. Because it was all metal, good torque retention was inherent with

this gasket. However, as engine displacement increased, the output resulted in

motionsthreat normally could not be accommodated by the elastic response of the

the embossed design. In addition, many times the land areas, especially between

cylinders, were reduced to a point where the legs of the emboss would fall inside the

ports, making adequate sealing impossible.

14

1965-1975

Zone D: With the development of rubber- fibre facing materials by the gasket paper

manufacturers came improved designs. The majority of these design incorporated a

tanged or perforated- core steel sheet, with these new facing materials mechanically

clinched to either side of the core thus providing soft surfaces of sealing material for

water and oil sealing. One of the major requirements of gaskets in this time zone was

that they function without need for a retorque operation on the cylinder head bolts.

Retorquing still is specified on some foreign made engines but is essentially non-

existent in today’sAmerican made engines. While this may not appear a major

requirement, it is indeed major, since the retorque operation greatly aids gasket

performance.

1975-Present

Zone E:graphite facings became popular in this time zone. Graphite has good

sealability and relaxation properties and high heat resistant. One of the newer

constructions eliminates the perforated core and uses an unbroken steel core to

which an adhesive is applied for bonding the facings.

This laminated gasket has been adopted on many of the more difficult sealing

applications. This type of gasket body can be embossed to achieve higher sealing

stress at particular passage ways. Another technique used to seal critical passage

ways on today’s engines involves silk screening to print elastomeric beads at these 15

locations. In addition, many improvements in seal, antistic, and antifret coating have

been incorporated in the latest gasket constructions.

Currently, a new array of lightweight, high output gasoline and diesel engines both

naturally aspirated and turbo charged is being developed. The gaskets industry is

involved in extensive R&D programs designed to seal these new families of engines.

Time will show even newer concepts being utilized in the head gaskets for these

engines

A new line-up of gaskets incorporating multiple layers of embossed, spring

temper stainless steel with rubber coatings has become popular. These gaskets

16

exhibit little exchange during engine operation use of spring temper stainless for

embossed layers results in high elastic recoveries.

17

Chapter 4

COMBUSTION SEALING

18

Chapter 4

COMBUSTION SEALING

In most cases, atinplate or zinc-plate armor is used for sealing the combustion

gases of spark ignition engines. The thickness of the armor is a function of the

thicknesses and type of facing material. The overlap and heel are sized for the

specific engine, to establish a proper unit seal load at the combustion chamber. The

heel may be sized differently at various positions around the combustion chamber in

order to obtain the proper unit loading at these positions. High-output engines

and/or turbocharged engines normally require stainless steel armor for improved

high-temperature and fatigue resistance. Types 430,304 and 321 stainless steel are

commonly used.

19

In the case of diesel applications, an armored gasket is not generally adequate. Only

armors of a certain thickness can be formed and imbedded into given gasket bodies,

and the thicknesses that normally fill these requirements are not structurally

sufficient to withstand the high combustion pressures of most diesel engines. As a

result other means for sealing combustions are necessary for these applications. The

most popular incorporates low carbon steel ring. This ring gives a high unit sealing

stress at very low loading and is widely used in today’s diesel engines. The wire is

butt welded and general attached to the gasket body by means of a stainless steel

armor wrapping. In some cases, the wrapping may be tabbed to reduce the load

20

required to imbed the armor into the body, thus increasing the loading on the wire

ring.

In some case stainless steel, wires are needed to withstand the heat and

fatigue characteristic inherent in particular engines. An example is the case where

precombustion chambers experience high thermal and mechanical movements.

There are some gaskets where more than one wire may be utilised to achieve the

desired sealing requirements of the engine.

Armored embossed metal is also used to seal combustion in number of

engines. Varying the height and the width of emboss results in a wide range of load-

compression properties. When embossing is made from the core of the gasket body

variation in the thickness tolerance are minimised since the emboss and the core are

made from the same piece of metal. Stainless or low carbon steel are used as

armors.

21

Diesel engines frequently have wet liners, and the gasket is usually charged

with sealing the intersection of the liner and the crankcase. During engine operation,

there is motion between the liner and the block and the likelihood of erosion of the

liner seat is high. As a result, coolant can leak to the top the deck; the gasket is

required to seal at this location. In some case, the soft surface tis used to seal; in

other cases , the heel of the armor is extended to cover the intersection for sealing

purposes. Engine testing normally dictates which is better. Some manufacturers are

using room temperature vulcanizing (RTV) silicon to seal this application.

22

There are other engines that have liner design that incorporate ridges and, in

some cases, grooves in the cylinder head. This results in coining, or imbedding, of the

gasket for improved combustion gas sealing. Another gasket design used on ridged

liner engines is a thick (0.080”) steel plate. i.e. embossed for improved combustion

sealing.

23

24

A unique gasket, which is used to seal very large diesel engines, uses copper

clad steel that has been etched away at various locations. The etching removes the

copper from specific areas there by permitting high unit loading at other location for

improved combustion gas sealing.

25

One of the items to be considered in the design of combustion sealing is bore

distortion. Some of the designs may need supplementary aids to keep bore distortion

within acceptable limits. A few of the techniques used for this include the extending

the combustion armor heel at specific locations, overlapping the heel around the

gasket body, generally at the ends of the gasket, and depositing beads or areas of

rigid materials at preselected points. All of these techniques essentially change the

load transmitting characteristics of the gasket and are useful for minimizing head

bending as well as reducing bore distortion.

26

In some engines, the back to back location of exhaust valves results in high

thermal growth in the area between cylinder bores. If excessive, this growth can

result in combustion leakage. One means of improving the sealing in this area is to

incorporate a metal shim in the gasket at this location. The shim acts as a stopper,

permitting the gasket to resist the thermal growth and enhance sealing.

Air cooled engines have somewhat reduced requirements regarding head

gasket sealing. Since there are no cooling water passage ways slight combustion gas

leakage can be permitted as long as:

1) Engine performance is not affected

2) The gasket is not affected by leakage.

Most of the gaskets for these engines consist of metal tanged core on both

outer surfaces and a high temperature resistant fibrous core material. Because these

engines are made mainly from aluminium high thermal motions occur. The metal

surfaces of the gasket permit head and block motions to occur without serious effect

to the gasket’s sealing ability. Embossed metal gaskets are also used on these

engines, especially when high heat transfer through the gasket is required

27

Bibliography:

1) Gasket and Gasketed joint by John H. Bickford

2) Google.

3) Wikipidea

28