Jeep Wrangler (2018 year). Manual — part 28

Cooling System

WARNING!

• You or others can be badly burned by hot engine

coolant (antifreeze) or steam from your radiator. If
you see or hear steam coming from under the hood,
do not open the hood until the radiator has had time
to cool. Never open a cooling system pressure cap
when the radiator or coolant bottle is hot.

• Keep hands, tools, clothing, and jewelry away from

the radiator cooling fan when the hood is raised. The
fan starts automatically and may start at any time,
whether the engine is running or not.

• When working near the radiator cooling fan, discon-

nect the fan motor lead or turn the ignition to the
OFF mode. The fan is temperature controlled and can
start at any time the ignition is in the ON mode.

Coolant Checks

Check the engine, battery (if equipped), intercooler (if

equipped), and Motor Generator Unit (MGU) (if equipped)

coolant (antifreeze) protection every 12 months (before the

onset of freezing weather, where applicable). If the engine,

battery (if equipped), intercooler (if equipped), and MGU

(if equipped) coolant (antifreeze) is dirty or rusty in

appearance, the system should be drained, flushed and

refilled with fresh coolant (antifreeze). Check the front of

the A/C condenser (if equipped) or radiator for any

accumulation of bugs, leaves, etc. If dirty, clean by gently

spraying water from a garden hose vertically down the face

of the A/C condenser (if equipped) or the back of the

radiator core.
Check the engine, battery (if equipped), intercooler (if

equipped), and MGU (if equipped) cooling system hoses

for brittle rubber, cracking, tears, cuts, and tightness of the

connection at the coolant recovery bottle and radiator.

Inspect the entire system for leaks. DO NOT REMOVE

THE COOLANT PRESSURE CAP WHEN THE COOLING

SYSTEM IS HOT.

Cooling System — Drain, Flush And Refill

NOTE:

Some vehicles require special tools to add coolant

properly. Failure to fill these systems properly could lead to

severe internal engine damage. If any coolant is needed to

be added to the system please contact an local authorized

dealer.
If the engine coolant (antifreeze) is dirty or contains visible

sediment, have an authorized dealer clean and flush with

OAT coolant (antifreeze) (conforming to MS.90032).

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Refer to the “Maintenance Plan” in this section for the

proper maintenance intervals.

Selection Of Coolant

Refer to “Fluids And Lubricants” in “Technical Specifica-

tions” for further information.

NOTE:
• Mixing of engine coolant (antifreeze) other than speci-

fied Organic Additive Technology (OAT) engine coolant

(antifreeze), may result in engine damage and may

decrease corrosion protection. Organic Additive Tech-

nology (OAT) engine coolant is different and should not

be mixed with Hybrid Organic Additive Technology

(HOAT) engine coolant (antifreeze) or any “globally

compatible” coolant (antifreeze). If a non-OAT engine

coolant (antifreeze) is introduced into the cooling system

in an emergency, the cooling system will need to be

drained, flushed, and refilled with fresh OAT coolant

(conforming to MS.90032), by an authorized dealer as

soon as possible.

• Do not use water alone or alcohol-based engine coolant

(antifreeze) products. Do not use additional rust inhibi-

tors or antirust products, as they may not be compatible

with the radiator engine coolant and may plug the

radiator.

• This vehicle has not been designed for use with propyl-

ene glycol-based engine coolant (antifreeze). Use of

propylene glycolbased engine coolant (antifreeze) is not

recommended.

• Some vehicles require special tools to add coolant prop-

erly. Failure to fill these systems properly could lead to

severe internal engine damage. If any coolant is needed

to be added to the system please contact your local

authorized dealer.

Adding Coolant

Your vehicle has been built with an improved engine

coolant (OAT coolant conforming to MS.90032) that allows

extended maintenance intervals. This engine coolant (anti-

freeze) can be used up to ten years or 150,000 miles

(240,000 km) before replacement. To prevent reducing this

extended maintenance period, it is important that you use

the same engine coolant (OAT coolant conforming to

MS.90032) throughout the life of your vehicle.

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SERVICING AND MAINTENANCE

439

Please review these recommendations for using Organic

Additive Technology (OAT) engine coolant (antifreeze)

that meets the requirements of FCA Material Standard

MS.90032. When adding engine coolant (antifreeze):
• We recommend using Mopar Antifreeze/Coolant 10

Year/150,000 Mile (240,000 km) Formula OAT (Organic

Additive Technology) that meets the requirements of

FCA Material Standard MS.90032.

• Mix a minimum solution of 50% OAT engine coolant

that meets the requirements of FCA Material Standard

MS.90032 and distilled water. Use higher concentrations

(not to exceed 70%) if temperatures below −34°F (−37°C)

are anticipated. Please contact an authorized dealer for

assistance.

• Use only high purity water such as distilled or deionized

water when mixing the water/engine coolant (anti-

freeze) solution. The use of lower quality water will

reduce the amount of corrosion protection in the engine

cooling system.

NOTE:
• It is the owner’s responsibility to maintain the proper

level of protection against freezing according to the

temperatures occurring in the area where the vehicle is

operated.

• Some vehicles require special tools to add coolant prop-

erly. Failure to fill these systems properly could lead to

severe internal engine damage. If any coolant is needed

to be added to the system, please contact a local autho-

rized dealer.

• Mixing engine coolant (antifreeze) types is not recom-

mended and can result in cooling system damage. If

HOAT and OAT coolant are mixed in an emergency,

have a authorized dealer drain, flush, and refill with

OAT coolant (conforming to MS.90032) as soon as pos-

sible.

Cooling System Pressure Cap

The cap must be fully tightened to prevent loss of engine

coolant (antifreeze), and to ensure that engine coolant

(antifreeze) will return to the radiator from the coolant

expansion bottle/recovery tank if so equipped.

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The cap should be inspected and cleaned if there is any

accumulation of foreign material on the sealing surfaces.

WARNING!

• Do not open hot engine cooling system. Never add

engine coolant (antifreeze) when the engine is over-
heated. Do not loosen or remove the cap to cool an
overheated engine. Heat causes pressure to build up
in the cooling system. To prevent scalding or injury,
do not remove the pressure cap while the system is
hot or under pressure.

• Do not use a pressure cap other than the one speci-

fied for your vehicle. Personal injury or engine
damage may result.

Disposal Of Used Coolant

Used ethylene glycol-based coolant (antifreeze) is a regu-

lated substance requiring proper disposal. Check with your

local authorities to determine the disposal rules for your

community. To prevent ingestion by animals or children,

do not store ethylene glycol-based coolant in open contain-

ers or allow it to remain in puddles on the ground. If

ingested by a child or pet, seek emergency assistance

immediately. Clean up any ground spills immediately.

Coolant Level

The coolant bottle provides a quick visual method for

determining that the coolant level is adequate. With the

engine OFF and cold, the level of the engine coolant

(antifreeze) in the bottle should be between the ranges

indicated on the bottle.
The radiator normally remains completely full, so there is

no need to remove the radiator/coolant pressure cap

unless checking for engine coolant (antifreeze) freeze point

or replacing coolant. Advise your service attendant of this.

As long as the engine operating temperature is satisfactory,

the coolant bottle need only be checked once a month.
When additional engine coolant (antifreeze) is needed to

maintain the proper level, only OAT coolant that meets the

requirements of FCA Material Standard MS.90032 should

be added to the coolant bottle. Do not overfill.

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Engine Coolant Level — 2.0L

WARNING!

• Do not open hot engine cooling system. Never add

engine coolant (antifreeze) when the engine is over-
heated. Do not loosen or remove the cap to cool an
overheated engine. Heat causes pressure to build up
in the cooling system. To prevent scalding or injury,
do not remove the pressure cap while the system is
hot or under pressure.

• Do not use a pressure cap other than the one speci-

fied for your vehicle. Personal injury or engine
damage may result.

With the engine OFF and cold, the level of the engine

coolant should be within the OK range between the ADD

and FULL range on the dipstick.
1. Remove the cap with level dipstick from the engine

coolant bottle.

2. Clean off the coolant from the dipstick.
3. Rest the cap on the opening of the coolant bottle without

tightening the cap.

4. Remove the cap with dipstick and check the coolant

level on the dipstick.

The radiator normally remains completely full, so there is

no need to remove the radiator/coolant pressure cap

unless checking for engine coolant (antifreeze) freeze point

or replacing coolant. Advise your service attendant of this.

As long as the engine operating temperature is satisfactory,

the coolant bottle need only be checked once a month.
When additional engine coolant (antifreeze) is needed to

maintain the proper level, only OAT coolant that meets the

requirements of FCA Material Standard MS.90032 should

be added to the coolant bottle. Do not overfill.

Points To Remember

NOTE:

When the vehicle is stopped after a few miles/

kilometers of operation, you may observe vapor coming

from the front of the engine compartment. This is normally

a result of moisture from rain, snow, or high humidity

accumulating on the radiator and being vaporized when

the thermostat opens, allowing hot engine coolant (anti-

freeze) to enter the radiator.
If an examination of your engine compartment shows no

evidence of radiator or hose leaks, the vehicle may be

safely driven. The vapor will soon dissipate.

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• Do not overfill the coolant expansion bottle.
• Check the coolant freeze point in the radiator and in the

coolant expansion bottle. If engine coolant (antifreeze)

needs to be added, the contents of the coolant expansion

bottle must also be protected against freezing.

• If frequent engine coolant (antifreeze) additions are

required, the cooling system should be pressure tested

for leaks.

• Maintain engine coolant (antifreeze) concentration at a

minimum of 50% OAT coolant (conforming to

MS.90032) and distilled water for proper corrosion pro-

tection of your engine which contains aluminum com-

ponents.

• Make sure that the coolant expansion bottle overflow

hoses are not kinked or obstructed.

• Keep the front of the radiator clean. If your vehicle is

equipped with air conditioning, keep the front of the

condenser clean.

• Do not change the thermostat for Summer or Winter

operation. If replacement is ever necessary, install ONLY

the correct type thermostat. Other designs may result in

unsatisfactory engine coolant (antifreeze) performance,

poor gas mileage, and increased emissions.

Brake System

In order to assure brake system performance, all brake

system components should be inspected periodically. Refer

to the “Maintenance Plan” in this section for the proper

maintenance intervals.

WARNING!

Riding the brakes can lead to brake failure and possi-
bly a collision. Driving with your foot resting or riding
on the brake pedal can result in abnormally high brake
temperatures, excessive lining wear, and possible
brake damage. You would not have your full braking
capacity in an emergency.

Fluid Level Check — Brake Master Cylinder

The fluid level of the master cylinder should be checked

whenever the vehicle is serviced, or immediately if the

brake system warning light is on. If necessary, add fluid to

bring level within the designated marks on the side of the

reservoir of the brake master cylinder. Be sure to clean the

top of the master cylinder area before removing cap. With

disc brakes, fluid level can be expected to fall as the brake

pads wear. Brake fluid level should be checked when pads

are replaced. If the brake fluid is abnormally low, check the

system for leaks.

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443

Refer to “Fluids And Lubricants” in “Technical Specifica-

tions” for further information.

WARNING!

• Use only manufacturer’s recommended brake fluid.

Refer to “Fluids And Lubricants” in “Technical
Specifications” for further information. Using the
wrong type of brake fluid can severely damage your
brake system and/or impair its performance. The
proper type of brake fluid for your vehicle is also
identified on the original factory installed hydraulic
master cylinder reservoir.

• To avoid contamination from foreign matter or mois-

ture, use only new brake fluid or fluid that has been
in a tightly closed container. Keep the master cylin-
der reservoir cap secured at all times. Brake fluid in
a open container absorbs moisture from the air
resulting in a lower boiling point. This may cause it
to boil unexpectedly during hard or prolonged brak-
ing, resulting in sudden brake failure. This could
result in a collision.

(Continued)

WARNING! (Continued)

• Overfilling the brake fluid reservoir can result in

spilling brake fluid on hot engine parts, causing the
brake fluid to catch fire. Brake fluid can also damage
painted and vinyl surfaces, care should be taken to
avoid its contact with these surfaces.

• Do not allow petroleum based fluid to contaminate

the brake fluid. Brake seal components could be
damaged, causing partial or complete brake failure.
This could result in a collision.

Front/Rear Axle Fluid

For normal service, periodic fluid level checks are not

required. When the vehicle is serviced for other reasons the

exterior surfaces of the axle assembly should be inspected.

If gear oil leakage is suspected inspect the fluid level. Refer

to “Fluids And Lubricants” in “Technical Specifications”

for further information.

Fluid Level Check

Lubricant should be approximately 1/8 inch (3 mm) below

the bottom edge of the oil fill hole.

NOTE:

Make sure that the vehicle is level and supported

by the axles

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Adding Fluid

Add lubricant only at the fill hole and only to the level

specified above.

Selection Of Lubricant

Use only the manufacturer’s recommended fluid. Refer to

“Fluids And Lubricants” in “Technical Specifications” for

further information.

Transfer Case

Selection Of Lubricant

Use only the manufacturer’s recommended fluid. Refer to

“Fluids And Lubricants” in “Technical Specifications” for

further information.

Fluid Level Check

This fluid level can be checked by removing the filler plug.

The fluid level should be to the bottom edge of the filler

plug hole with the vehicle in a level position.

Drain And Refill

Refer to the “Maintenance Plan” in this section for the

proper maintenance intervals.

Manual Transmission

Selection Of Lubricant

Use only manufacturer’s recommended manual transmis-

sion fluid. Refer to “Fluids And Lubricants” in “Technical

Specifications” for further information.

Fluid Level Check

Check the fluid level by removing the fill plug. The fluid

level should be between the bottom of the fill hole and a

point not more than 3/16 of an inch (4.76 mm) below the

bottom of the hole.
Add fluid, if necessary, to maintain the proper level.

Frequency Of Fluid Change

Under normal operating conditions, the fluid installed at

the factory will give satisfactory lubrication for the life of

the vehicle. If the fluid becomes contaminated with water,

it should be changed immediately. Otherwise, change the

fluid as recommended in the Maintenance Plan. Refer to

the “Maintenance Plan” for the proper maintenance inter-

vals.

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445

Automatic Transmission

Selection Of Lubricant

It is important to use the proper transmission fluid to

ensure optimum transmission performance and life. Use

only the manufacturer’s specified transmission fluid. Refer

to “Fluids And Lubricants” in “Technical Specifications”

for fluid specifications. It is important to maintain the

transmission fluid at the correct level using the recom-

mended fluid.

NOTE:

No chemical flushes should be used in any trans-

mission; only the approved lubricant should be used.

CAUTION!

Using a transmission fluid other than the manufactur-
er’s recommended fluid may cause deterioration in
transmission shift quality and/or torque converter
shudder. Refer to “Fluids And Lubricants” in “Techni-
cal Specifications” for fluid specifications.

Special Additives

The manufacturer strongly recommends against using any

special additives in the transmission. Automatic Transmission

Fluid (ATF) is an engineered product and its performance

may be impaired by supplemental additives. Therefore, do

not add any fluid additives to the transmission. Avoid using

transmission sealers as they may adversely affect seals.

CAUTION!

Do not use chemical flushes in your transmission as
the chemicals can damage your transmission compo-
nents. Such damage is not covered by the New Vehicle
Limited Warranty.

Fluid Level Check

The fluid level is preset at the factory and does not require

adjustment under normal operating conditions. Routine

fluid level checks are not required; therefore the transmis-

sion has no dipstick. An authorized dealer can check your

transmission fluid level using special service tools. If you

notice fluid leakage or transmission malfunction, visit an

authorized dealer immediately to have the transmission

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fluid level checked. Operating the vehicle with an im-

proper fluid level can cause severe transmission damage.

CAUTION!

If a transmission fluid leak occurs, visit an authorized
dealer immediately. Severe transmission damage may
occur. An authorized dealer has the proper tools to
adjust the fluid level accurately.

Fluid And Filter Changes

Under normal operating conditions, the fluid installed at

the factory will provide satisfactory lubrication for the life

of the vehicle.
Routine fluid and filter changes are not required. However,

change the fluid and filter if the fluid becomes contami-

nated (with water, etc.), or if the transmission is disas-

sembled for any reason.

RAISING THE VEHICLE

In the case where it is necessary to raise the vehicle, go to

an authorized dealer or service station.

TIRES

Tire Safety Information

Tire safety information will cover aspects of the following

information: Tire Markings, Tire Identification Numbers,

Tire Terminology and Definitions, Tire Pressures, and Tire

Loading.

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Tire Markings

NOTE:
• P (Passenger) — Metric tire sizing is based on U.S.

design standards. P-Metric tires have the letter “P”

molded into the sidewall preceding the size designation.

Example: P215/65R15 95H.

• European — Metric tire sizing is based on European

design standards. Tires designed to this standard have

the tire size molded into the sidewall beginning with the

section width. The letter

⬙P⬙ is absent from this tire size

designation. Example: 215/65R15 96H.

• LT (Light Truck) — Metric tire sizing is based on U.S.

design standards. The size designation for LT-Metric

tires is the same as for P-Metric tires except for the letters

“LT” that are molded into the sidewall preceding the

size designation. Example: LT235/85R16.

• Temporary spare tires are designed for temporary emer-

gency use only. Temporary high pressure compact spare

tires have the letter “T” or “S” molded into the sidewall

preceding the size designation. Example: T145/80D18

103M.

• High flotation tire sizing is based on U.S. design stan-

dards and it begins with the tire diameter molded into

the sidewall. Example: 31x10.5 R15 LT.

Tire Markings

1 — U.S. DOT Safety
Standards Code (TIN)

4 — Maximum Load

2 — Size Designation

5 — Maximum Pressure

3 — Service Description

6 — Treadwear, Traction
and Temperature Grades

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Tire Sizing Chart

EXAMPLE:

Example Size Designation: P215/65R15XL 95H, 215/65R15 96H, LT235/85R16C, T145/80D18 103M, 31x10.5 R15 LT
P

= Passenger car tire size based on U.S. design standards, or

ⴖ. blank. ⴖ = Passenger car tire based on European design standards, or
LT

= Light truck tire based on U.S. design standards, or

T or S

= Temporary spare tire or

31

= Overall diameter in inches (in)

215, 235, 145

= Section width in millimeters (mm)

65, 85, 80

= Aspect ratio in percent (%)

– Ratio of section height to section width of tire, or
10.5

= Section width in inches (in)

R

= Construction code

–

⬙R⬙ means radial construction, or

–

⬙D⬙ means diagonal or bias construction

15, 16, 18

= Rim diameter in inches (in)

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EXAMPLE:

Service Description:
95

= Load Index

– A numerical code associated with the maximum load a tire can carry
H

= Speed Symbol

– A symbol indicating the range of speeds at which a tire can carry a load corresponding to its load index under cer-

tain operating conditions

– The maximum speed corresponding to the speed symbol should only be achieved under specified operating condi-

tions (i.e., tire pressure, vehicle loading, road conditions, and posted speed limits)

Load Identification:
Absence of the following load identification symbols on the sidewall of the tire indicates a Standard Load (SL) tire:

• XL = Extra load (or reinforced) tire, or

• LL = Light load tire or

• C, D, E, F, G = Load range associated with the maximum load a tire can carry at a specified pressure
Maximum Load

– Maximum load indicates the maximum load this tire is designed to carry

Maximum Pressure

– Maximum pressure indicates the maximum permissible cold tire inflation pressure for this tire

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Tire Identification Number (TIN)

The TIN may be found on one or both sides of the tire;

however, the date code may only be on one side. Tires with

white sidewalls will have the full TIN, including the date

code, located on the white sidewall side of the tire. Look for

the TIN on the outboard side of black sidewall tires as

mounted on the vehicle. If the TIN is not found on the

outboard side, then you will find it on the inboard side of

the tire.

EXAMPLE:

DOT MA L9 ABCD 0301

DOT

= Department of Transportation

– This symbol certifies that the tire is in compliance with the U.S. Department of Transportation tire safety standards

and is approved for highway use

MA

= Code representing the tire manufacturing location (two digits)

L9

= Code representing the tire size (two digits)

ABCD

= Code used by the tire manufacturer (one to four digits)

03

= Number representing the week in which the tire was manufactured (two digits)

– 03 means the 3rd week
01

= Number representing the year in which the tire was manufactured (two digits)

– 01 means the year 2001

– Prior to July 2000, tire manufacturers were only required to have one number to represent the year in which the

tire was manufactured. Example: 031 could represent the 3rd week of 1981 or 1991

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Tire Terminology And Definitions

Term

Definition

B-Pillar

The vehicle B-Pillar is the structural member of the body located be-

hind the front door.

Cold Tire Inflation Pressure

Cold tire inflation pressure is defined as the tire pressure after the

vehicle has not been driven for at least three hours, or driven less

than 1 mile (1.6 km) after sitting for a minimum of three hours. In-

flation pressure is measured in units of PSI (pounds per square inch)

or kPa (kilopascals).

Maximum Inflation Pressure

The maximum inflation pressure is the maximum permissible cold

tire inflation pressure for this tire. The maximum inflation pressure is

molded into the sidewall.

Recommended Cold Tire Inflation Pressure

Vehicle manufacturer’s recommended cold tire inflation pressure as

shown on the tire placard.

Tire Placard

A label permanently attached to the vehicle describing the vehicle’s

loading capacity, the original equipment tire sizes and the recom-

mended cold tire inflation pressures.

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Tire Loading And Tire Pressure

NOTE:

The proper cold tire inflation pressure is listed on

the driver’s side B-Pillar or the rear edge of the driver’s

side door.
Check the inflation pressure of each tire, including the

spare tire (if equipped), at least monthly and inflate to the

recommended pressure for your vehicle.

Example Tire Placard Location (Door)

Example Tire Placard Location (B-Pillar)

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