Mercedes C300 Thermostat Replacement DIY (2015-2018 Mercedes C300, GLC300, SLC300, SLK300, E300)

►The Mercedes M274 engine was the entry-level powerplant for a handful of models in the mid-2010s. Now that those models are common in the second-hand market, jobs like thermostat replacements are falling on owners who are out of warranty. It's become especially regular with that engine, as the plastics can crack, and the thermostat can fail in the open position. While that is the better of the ways it can fail, not letting your engine reach operating temperature can have lasting harmful effects, so ensure you replace it as soon as possible.
You can take your car to the dealer to have this fixed, but it will cost around $2000 in parts and labor. Buying the parts from us and following this DIY will cost you a bit more than 10% of what the dealer would normally charge you. Replacing your M274's thermostat involves opening up the cooling system, so you will have to bleed it afterward, plus having to drain some coolant can get messy. However, some extra time spent cleaning and being careful is a lot easier to swallow than the money to pay a professional to do something you can tackle yourself.
In this video, Mike Hidalgo, FCP Euro's Professional DIYer, replaces the thermostat on a W205 Mercedes C300.
Shop the parts used in this video:
Mercedes Thermostat Replacement Kit:
www.fcpeuro.co...
00:00 - Intro
This video applies to the following vehicles:
Mercedes-Benz C300
2015 Mercedes-Benz C300
2016 Mercedes-Benz C300
2017 Mercedes-Benz C300
2018 Mercedes-Benz C300
Mercedes-Benz GLC300
2016 Mercedes-Benz GLC300
2017 Mercedes-Benz GLC300
2018 Mercedes-Benz GLC300
Mercedes-Benz SLK300
2016 Mercedes-Benz SLK300
Mercedes-Benz SLC300
2017 Mercedes-Benz SLC300 Base
2018 Mercedes-Benz SLC300 Base
Mercedes-Benz E300
2017 Mercedes-Benz E300
2018 Mercedes-Benz E300
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[@marcsmith3881]

Damn! What did Mercedes do with these newer engines? I have replaced a few crankcase vent valves, but this goes a little deeper in this area. I wouldn't recommend this for someone that doesn't have much experience in this area. I can see dozens of places for mistakes. Thats great information that they have extended the warranty because they failed so bad that the vent valve was on national backorder for months. Excellent video!

[@michaelschneider-]

FCP Euro is pretty fine shop. I get DIY parts for our '94 E-320 coupe (C124) .. About to pull the head for the head gasket R&R .... And all the other "While You're in There" components. The Coupe is the Bomb road-trip auto .. 2nd owner. . My uncle RIP ordered the coupe new. Just breaking in the 3.2l inline 6 now at 98K miles. Cheers, Vail, Colorado

[@fcpeuro]

Nice work , thank you for wrenching with us!

[@josh6pack]

Watched this video a few times before I started on this. Couldn't find a set of E10 sockets in time, so i just bought a single E10. Now that I'm off in it, there's a 5th eTorx on bottom of the intercooler bracket that's a bigger, unknown size. When I find out what it is I'll reply to this post. I was hoping someone would have already commented on it but nope. I get to be the guy. Avenge me.

[@josh6pack]

So I buggered the bolt up a bit with the vice grips trying to avoid buying the proper socket, so the E12 may work, but I torqued it back on with the E14.

[@markyo99]

Wow! Very thorough instructions. Thank you very much!

[@danieltonnessen656]

Very good video great instructions and instructor

[@HowardChang-mo5ln]

Very excellent step by step video, Thank you sir

[@ninevahkeith]

Can I apply this to my q50. There's alot more room in the bay. I just wish I was certain that the engines are identical, I see the differences under the hood but I'm not sure if it's just packaging or are the mercedes units different or are from a mote current revision,

[@giuseppegreco3603]

Very great video

[@lionking2950]

Great 👍🏻 Video ❤ it

[@beastZz706]

what about the intercooler coolant. does the main reservoir go into the intercooler reservoir? if not how much coolant does the intercooler take because i cant find any info on this. thanks

[@beastZz706]

question did the main lower radiator hose remove all of the 2 gallons in the system? because i want to replace all of the coolant with new. instead of adding new coolant with the old coolant. w205 edit: there is a petcock under the radiator that releases 4 litters. so i did 3 flushes with distilled water than added 4 litters concentrated to get 50 50 mix. the main radiator hose is hard to remove unless you raise the car alot and get under it with some leverage.

[@AndrewKidd14145]

To answer your question. Radiator hose drains system. This job drains the system entirely. As for just removing hose in case you were just talking about that. It won’t remove all of the stuff in the block there will be a bit left.

[@youzen8606]

Will it trigger any code before failing?

[@Taadow81]

Yes P0128

[@kelvinvillatoro9254]

Does this apply to a e300 (2019)! Replies are greatly appreciated

[@WhitneyBrown-t5x]

Yes

[@youzen8606]

Will it trigger any code before it fails?

[@adriannaandwhip]

@@youzen8606 yes usually it will say water temp is below thermostat set point

[@bmwlane8834]

I would definitely consider cleaning intake valves and possibly changing out the pvc system.

[@fcpeuro]

Great notes! We have a PCV DIY for this model as well!

[@pirasannanandakumar9626]

How much labour time for this job

[@Aldo_98_503]

Exactly I need to know how much I’m gonna charge and how long

[@Ale-ze1fk]

The part on how to remove air from the system is missing.😉

[@IgorD33]

They did say to check level after it cools down. Maybe the system would bleed on its own after it reaches operating temp?

[@fcpeuro]

These systems on the Mercedes are very simple and self bleeding. You need to run it to temp and then let it fully cool down and top off the level as needed, that's it!

[@FLAandy]

The best DIY channel on KZbin. I will be attempting this project very soon. Wish me luck mu guy

[@daveh2612]

Uh oh 50 minute video to change a thermostat.

[@r.weaver3769]

Don't forget, many little segments are time lapsed. Probably two hours.

[@daveh2612]

@@r.weaver3769 All plastic garbage, super expensive, take half the engine apart to change, stretch bolts etc

[@pirasannanandakumar9626]

How long does this job pay

[@konstantinosantonelos427]

2hours job easy the first time