Mercedes-Benz S420 Car Thermostat Replacement at your home or office.

Our mobile mechanics offer services 7 days a week. Upfront and transparent pricing.

Estimate price near me

Service Location

Customer Ratings

(12)

Included for free with this service

Online Booking

Mechanic comes to you

12-month / 12k-mile warranty

Free 50 point safety inspection

Our certified mobile mechanics can come to your home or office 7 days a week between 7 AM and 9 PM.

Customer Ratings

(12)

Car Thermostat Replacement Service

How much does a Car Thermostat Replacement cost?

On average, the cost for a Mercedes-Benz S420 Car Thermostat Replacement is $209 with $104 for parts and $104 for labor. Prices may vary depending on your location.

CarServiceEstimateShop/Dealer Price
1999 Mercedes-Benz S420V8-4.2LService typeCar Thermostat ReplacementEstimate$346.37Shop/Dealer Price$419.47 - $591.50
1996 Mercedes-Benz S420V8-4.2LService typeCar Thermostat ReplacementEstimate$325.15Shop/Dealer Price$398.98 - $573.13
1994 Mercedes-Benz S420V8-4.2LService typeCar Thermostat ReplacementEstimate$312.87Shop/Dealer Price$384.25 - $555.00
1998 Mercedes-Benz S420V8-4.2LService typeCar Thermostat ReplacementEstimate$322.37Shop/Dealer Price$395.45 - $567.48
1995 Mercedes-Benz S420V8-4.2LService typeCar Thermostat ReplacementEstimate$322.37Shop/Dealer Price$395.53 - $567.62
1997 Mercedes-Benz S420V8-4.2LService typeCar Thermostat ReplacementEstimate$322.37Shop/Dealer Price$395.50 - $567.56
Show example Mercedes-Benz S420 Car Thermostat Replacement prices

What is an engine cooling system thermostat and how does it work?

The car's engine cooling system thermostat is a small valve within a cooling system passageway that opens and closes in response to the temperature of the circulating engine coolant. When your car is first started and the coolant is cold, the valve in the thermostat will be in the closed position, circulating the coolant flow only within the engine instead of flowing to the radiator, which allows the engine to warm up fast, promoting fuel efficiency, low emissions, and reduced engine deposits. Once the engine coolant reaches the design temperature, usually around 195 degrees, the valve will open and close as you drive in order to maintain a coolant temperature typically between 195 to 225 degrees Fahrenheit.

Thermostat

When to consider replacing the engine cooling system thermostat:

  • Engine overheats. A thermostat with the valve stuck closed is a common cause of engine overheating. However, since there are other causes of overheating, a mechanic will thoroughly inspect the cooling system prior to condemning the thermostat. Since it is usually not known how badly the engine overheated, the mechanic will also try to determine if there is evidence that the cylinder head gasket was blown. If so, it would be repaired prior to replacing the thermostat.
  • Temperature gauge reads too low or too high. Thermostats can get sticky, causing the engine temperature to stray from the optimal range. Your dash-mounted temperature gauge will notify you of this malfunction.
  • Cooling system repairs. All thermostats eventually fail. Therefore, if the cooling system is already open for major repairs, such as water pump or radiator replacement, it is recommended to install a new thermostat simply as insurance against future breakdown.

How do mechanics replace the engine cooling system thermostat?

  • Once the engine is completely cold, the radiator cap is loosened and enough coolant is drained from the radiator so the coolant level is below the thermostat housing.
  • The thermostat housing is removed and the thermostat and gasket are extracted. Note that some cars have more than one cooling system thermostat and both might need replacement.
  • All mounting surfaces on the thermostat housing are cleaned of old gasket material. A new gasket is applied and the thermostat is re-installed in the correct orientation and with the temperature sensing cylinder facing downward towards the engine.
  • The thermostat housing bolts are tightened to original equipment manufacturer (OEM) specifications using a calibrated inch-pound torque wrench.
  • The cooling system is refilled with the appropriate coolant type and the system is fully bled of all air.
  • The car engine is run until the normal operating temperature is reached, and while taking precautions with the hot coolant, the coolant level is rechecked while confirming there is flow through the radiator — either visually or with an infrared temperature gun. This will confirm the thermostat is open. Finally, the engine is checked for leaks.

Is it safe to drive with an engine cooling system thermostat problem?

No. If it has been determined that there is a thermostat problem, it should be repaired right away. Failure to do so can cause substantial and costly damage to the engine.

When replacing the engine cooling system thermostat keep in mind:

  • Engine overheating due to causes other than a faulty thermostat, will themselves damage a thermostat. Therefore, always replace the thermostat if the engine overheats, even if the thermostat was not the initial cause of the overheating.
  • The thermostat should be replaced anytime you have major work done on the coolant system. It is convenient and costs little during such repairs and insurance against future breakdown.
  • OEM thermostats are the best ones to use and you can request your mechanic to install only the OEM thermostat. Dealer supplied, OEM thermostats are sometimes more costly but are generally higher quality and specifically engineered for your car.

Fast and easy service at your home or office

Backed by 12-month, 12.000-mile guarantee


Meet some of our expert Mercedes-Benz mechanics

Real customer reviews from Mercedes-Benz owners like you.

Excellent Rating

(12)

Rating Summary
11
0
1
0
0
11
0
1
0
0

Anthony

5 years of experience
85 reviews
Anthony
5 years of experience
S420 1998 - Car is overheating - Sacramento, CA
showed up on time did diagnostics right away he was pretty accurate.

Manuel

10 years of experience
47 reviews
Manuel
10 years of experience
S420 1996 - Car is overheating - Naples, FL
Very prom and good mechanic .

Excellent Rating

(12)

Rating Summary
11
0
1
0
0
11
0
1
0
0
Number of Mercedes-Benz S420 services completed
132+
services done by our mechanics
TOTAL NUMBER OF EXPERT Mercedes-Benz MECHANICS
1100+
experts on our platform

Recent articles & questions

How Long Does an Alternator Belt Last?
Your Your car’s alternator is what delivers energy to your vehicle’s battery. It works by means of converting mechanical energy to electrical energy, taking power from the engine’s crankshaft and delivering it to the battery where it is stored. The...
P0304 OBD-II Trouble Code: Cylinder 4 Misfire Detected
P0304 code definition P0304 is a diagnostic trouble code seen when a misfire is detected in cylinder 4. This code may...
How to Replace an Air Conditioner Receiver Drier
The AC receiver/drier is stores and dries refrigerant. This component should be replaced if too much water enters the system or if leaks are found.

Could the low oil level sensor be accidentally knocked off during an oil change on a es330 Lexus 2005. My engine recently seized up.

Hi there. Look all around the engine and around the oil pan and filter. Look for any signs of oil leakage. If there is no oil leakage, then check the engine oil level. If the oil level is full, then...

New battery drained of power in one week

If the battery is new and charging system output has been measured and is within specifications, the only reason a battery will discharge is if the car sits for a long period of time (batteries will self-discharge even if not...

All my trouble and warning lights come on . Car runs good

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com