2018 LEXUS RCF cooling

392 6-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)WARNING
The engine compartment contains many mechan isms and fluids that may move suddenly,
become hot, or become electrically energize d. To avoid death or serious injury, observe
the following precautions. ■
When working on the engine compartment ●
Keep hands, clothing and tools away from the moving fan and engine drive belt.●
Be careful not to touch the engine, radiator, exhaust manifold, etc. right after driving
as they may be hot. Oil and other fluids may also be hot. ●
Do not leave anything that may burn easily, such as paper and rags, in the engine
compartment. ●
Do not smoke, cause sparks or expose an open flame to fuel or the battery. Fuel and
battery fumes are flammable. ●
Be extremely cautious when working on the battery. It contains poisonous and corro-
sive sulfuric acid. ■
When working near the electric cooling fans or radiator grille
Be sure the engine switch is off.
With the engine switch in IGNITION ON mode, the electric cooling fans may auto-
matically start to run if the air conditioning is on and/or the coolant temperature is high.
(  P. 406) ■
Safety glasses
Wear safety glasses to prevent flying or falling material, flui d spray, etc. from getting in
your eyes.
NOTICE ■
If you remove the air cleaner filter
Driving with the air cleaner f ilter removed may cause excessive engine wear due to dirt
in the air.

3976-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 6
Maintenance and care 
RC350/RC300 AWD
Engine compartment
Fuse boxes (  P. 429)
Battery (  P. 408)
Engine oil level dipstick
(  P. 400)
Engine coolant reservoir
(  P. 404)
Engine oil filler cap (  P. 402) Brake fluid reservoir (  P. 407)
Washer fluid tank (  P. 411)
Electric cooling fans
Condenser (  P. 406)
Radiator (  P. 406)1
2
3
4
5 6
7
8
9
10

398 6-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)
RC300
Fuse boxes (  P. 429)
Battery (  P. 408)
Engine oil level dipstick
(  P. 400)
Engine oil filler cap (  P. 402)
Engine coolant reservoir
(  P. 404)
Brake fluid reservoir (  P. 407) Washer fluid tank (  P. 411)
Electric cooling fans
Condenser (  P. 406)
Intercooler radiator (  P. 406)
Radiator (  P. 406)
Intercooler coolant reservoir
(  P. 404)1
2
3
4
5
6 7
8
9
10
11
12

3996-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 6
Maintenance and care 
RC F
Fuse boxes (  P. 429)
Battery (  P. 408)
Engine oil level dipstick
(  P. 400)
Engine coolant reservoir
(  P. 404)
Engine oil filler cap (  P. 402) Brake fluid reservoir (  P. 407)
Washer fluid tank (  P. 411)
Electric cooling fans
Condenser (  P. 406)
Radiator (  P. 406)1
2
3
4
5 6
7
8
9
10

4056-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 6
Maintenance and care ■
Intercooler coolant reservoir (RC300)
The coolant level is satisfactory if it is between the “F” and “L” lines on the res-
ervoir when the engine is cold.
Reservoir cap
“F” line
“L” line If the level is on or below the “L” line,
add coolant up to the “F” line.
(  P. 526)■
Coolant selection
Only use “Toyota Super Long Life Coolant” or a similar high qu ality ethylene glycol
based non-silicate, non-amine, non-nitrite, and non-borate coolant with long-life hybrid
organic acid technology.
U.S.A.:
“Toyota Super Long Life Coolant” is a mixt ure of 50% coolant and 50% deionized water.
(Minimum temperature: -31  F [-35  C])
Canada:
“Toyota Super Long Life Cool ant” is a mixture of 55% coolant and 45% deionized water.
(Minimum temperature: -44  F [-42  C])
For more details about engine coolant, contact your Lexus dealer. ■
If the coolant level drops within a short time of replenishing
Visually check the radiator, ho ses, engine and intercooler coolant reservoir caps, drain
cock and water pump.
If you cannot find a leak, have your Lexus de aler test the cap and check for leaks in the
cooling system. 1
2
3

406 6-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)Check the radiator, condenser and interc ooler radiator and clear away any for-
eign objects.
If any of the above parts are extremely dirt y or you are not sure of their condition,
have your vehicle inspecte d by your Lexus dealer.WARNING ■
When the engine is hot (RC350/RC300)
Do not remove the engine coolant reservoir cap, intercooler coolant reservoir cap and
coolant inlet cap. (  P. 530)
The cooling system may be under pressure and may spray hot coolant if the cap is
removed, causing serious injuries, such as burns. ■
When the engine is hot (RC F)
Do not remove the engine coolant reservoir cap. (  P. 530)
The cooling system may be under pressure and may spray hot coolant if the cap is
removed, causing serious injuries, such as burns.
NOTICE ■
When adding coolant
Coolant is neither plain water nor straight antifreeze. The correct mixture of water and
antifreeze must be used to provide proper lubrication, corrosion protection and cool-
ing. Be sure to read the antifreeze or coolant label.■
If you spill coolant
Be sure to wash it off with water to prevent it from damaging parts or paint.
Radiator, condenser and intercooler radiator (if equipped)
WARNING ■
When the engine is hot
Do not touch the radiator, condenser or inte rcooler as they may be hot and cause seri-
ous injuries, such as burns.

5257-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 7
When trouble arises WARNING ■
Avoiding battery fires or explosions
Observe the following precautions to preven t accidentally igniting the flammable gas
that may be emitted from the battery: ●
Make sure each jumper cable is connected to the correct terminal and that it is not
unintentionally in contact with any other than the intended terminal.●
Do not allow the other end of the jumper cab le connected to the “+” terminal to come
into contact with any other parts or metal surfaces in the area, such as brackets or
unpainted metal. ●
Do not allow the + and - clamps of the jump er cables to come in to contact with each
other. ●
Do not smoke, use matches, cigarette lighters or allow open flame near the battery. ■
Battery precautions
The battery contains poisonous and corrosive acidic electrolyte, while related parts
contain lead and lead compounds. Observ e the following precautions when handling
the battery: ●
When working with the battery, always wear safety glasses and take care not to allow
any battery fluids (acid) to come into cont act with skin, clothing or the vehicle body.●
Do not lean over the battery. ●
In the event that battery fluid comes into contact with the skin or eyes, immediately
wash the affected area with water and seek medical attention.
Place a wet sponge or cloth over the affected area until medical attention can be
received. ●
Always wash your hands afte r handling the battery support, terminals, and other bat-
tery-related parts. ●
Do not allow childre n near the battery.
NOTICE ■
When handling jumper cables
When connecting the jumper cables, ensure that they do not become entangled in the
cooling fans or engine drive belt.

5277-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 7
When trouble arises After the engine has cooled down suff iciently, inspect th e hoses and radiator
core (radiator) for any leaks.
Radiator
Cooling fans If a large amount of coolant leaks, immediately contact your Lexus dealer. 3
1
2
RC350/RC300 AWD 
RC300
RC F