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Hi everyone. I just got done replacing a bunch of components on my E300 4Matic 2017.
I changed the motor mounts, swapped the PCV valve with the breather hose, the thermostat, drained the coolant and will be filling it back up once everything is put back together, changed the spark plugs, and cleaned the valves. I also replaced the alternators voltage regulator as the brushes were almost gone on them. Replaced with an OEM Valeo part.
Below is a before and after shot:
I used non chlorinated brake clean, CRV valve cleaner (even though you’re supposed to use it through the air intake and the engine running, but I just sprayed it on the valves) with pick and air pressure and vacuum.
My question for anyone who might know the answer is:
Is there anything I need to do after I put coolant in the system and bleed the air out? It should start up after putting everything together, right? I’ve heard a couple of people tell me that the car might not start right away because it needs to build pressure and vacuum in the engine, and the fluids need to get to all the places.
Also, my local Mercedes dealer tells me that the engine requires only the coolant they sell, not to mix it with distilled water. Is this correct? I thought our engines require it to be a 50/50 mix.
Any info is helpful as I’m new to being an armature mechanic and don’t want to blow or warp my engine in any way 😂
Last edited by Affalterback; Jun 12, 2023 at 01:09 AM.
Couple questions for my own curiosity: how many miles do you have on your car? also, how difficult was it to get to the intake valves and clean them?
At the time of cleaning the car has 110,000 miles. The picture above was the worst valve so I decided to use that as a before and after. the valves were super clean compared to other cars with that mileage. I use only Mobil 1 premium fuel and change the oil regularly. So the valves are clean.
the difficulty is not bad if you are DIY savvy. You need to take off the inner cooler, remove the computer (recommended), battery, and intake plenum. You’ll have to replace the intake plenum gaskets when you remove it. Make sure you shut the valves one by one by turning the engine over manually. Make sure you turn it clock wise and don’t turn it counter clock wise.
if you need any help if you’re going to take on that project let me know, I can help as much as I can!
If those pictures are the worst valve carbon build up wise after a 110,000 miles, then this generation of Mercedes 4 cylinder engine separate the oil from the combustion much better than before. Audi had the worst carbon build up issue early on when they went to direct injection years ago. Thanks for the pictures.
Hi everyone. I just got done replacing a bunch of components on my E300 4Matic 2017.
I changed the motor mounts, swapped the PCV valve with the breather hose, the thermostat, drained the coolant and will be filling it back up once everything is put back together, changed the spark plugs, and cleaned the valves. I also replaced the alternators voltage regulator as the brushes were almost gone on them. Replaced with an OEM Valeo part.
Below is a before and after shot:
I used non chlorinated brake clean, CRV valve cleaner (even though you’re supposed to use it through the air intake and the engine running, but I just sprayed it on the valves) with pick and air pressure and vacuum.
My question for anyone who might know the answer is:
Is there anything I need to do after I put coolant in the system and bleed the air out? It should start up after putting everything together, right? I’ve heard a couple of people tell me that the car might not start right away because it needs to build pressure and vacuum in the engine, and the fluids need to get to all the places.
Also, my local Mercedes dealer tells me that the engine requires only the coolant they sell, not to mix it with distilled water. Is this correct? I thought our engines require it to be a 50/50 mix.
Any info is helpful as I’m new to being an armature mechanic and don’t want to blow or warp my engine in any way 😂
Great before and after photos.
MB sells both diluted and undiluted coolant. Sounds like your dealer sells diluted (50/50).
There is WIS posted around this site for coolant drain and fill. Nothing special, just fill er up and you might need to burp it a few times (run engine until hot, shut it down, top up coolant, repeat as often as needed).
If those pictures are the worst valve carbon build up wise after a 110,000 miles, then this generation of Mercedes 4 cylinder engine separate the oil from the combustion much better than before. Audi had the worst carbon build up issue early on when they went to direct injection years ago. Thanks for the pictures.
I agree. The only potential issue I see is the “knocking” or “wrist pin” issue the 274 engines have had in the past. I really hope mine stays strong and doesn’t crack a piston or anything.
MB sells both diluted and undiluted coolant. Sounds like your dealer sells diluted (50/50).
There is WIS posted around this site for coolant drain and fill. Nothing special, just fill er up and you might need to burp it a few times (run engine until hot, shut it down, top up coolant, repeat as often as needed).
thank you! I just asked my MB dealer if it’s still
the case to use pure coolant without diluting 50/50 and they said yes. They said there’s a service bulletin that said if mixed with water it’ll turn the coolant brown or into a darker color, and that’s why it’s not supposed to be mixed.
I called a couple of other Mercedes dealers and one told me they don’t know, and the other said to mix it 50/50. So I’m stuck as to what I should do. This is the coolant they sold to me:
however on the back it says to mix it 50/50:
in either case, I’m probably going to mix it as the container says MB recommend to mix. I just bought some Liqui Moli Radiator Cleaner additive and will be flushing out the cooling system about 2-3 times with distilled water before pouring in the actual coolant.
Ask for the service bulletin number, and someone on this forum can provide it for you. Maybe you can even ask the dealer themselves to show it or print it for you.
You posted a photo of undiluted 325.6 and the container label recommends 50/50 dilution. I would do as you plan and use the coolant, diluted with water.
You posted a photo of undiluted 325.6 and the container label recommends 50/50 dilution. I would do as you plan and use the coolant, diluted with water.
thank you for that info! Very helpful. I will be diluting it, and keeping an eye on the color through a few thousand miles to make sure it doesn’t turn brown or dark.
Update: changed the passenger side motor mount. It was such a pain in the *** to do. You HAVE TO remove the exhaust manifold and the thing above the catalytic converter.
a few of the aluminum coolant hoses from the turbo to the engine had to be removed as well. After pulling off the intake manifold the gasket fell apart into two pieces. So bad to replace that (it’s always a good idea to replace them anyway when removing).
While I had the gasket and exhaust manifold off of the engine, I decided to clean the surface and inside the ports of the engine. Wasn’t needed but might as well.
only thing left to do is put the inner cooler, throttle body, and the computer back in and do the coolant flush/fill.
From your following posts, you do not seem like an amateur mechanic at all! Quite impressive work you did for being a DIYer.
thank you for your kind words 🙂 it’s a learning process but I’d never be able to learn if I didn’t go at it. Next job is going to be removing the camshaft adjusters and the chain tensioner and replacing them as my engine had the outdated camshaft adjusters and not the new updated ones Mercedes put out for the M274 engines. So we’ll see how that goes
Hi everyone. I just got done replacing a bunch of components on my E300 4Matic 2017.
I changed the motor mounts, swapped the PCV valve with the breather hose, the thermostat, drained the coolant and will be filling it back up once everything is put back together, changed the spark plugs, and cleaned the valves. I also replaced the alternators voltage regulator as the brushes were almost gone on them. Replaced with an OEM Valeo part.
I used non chlorinated brake clean, CRV valve cleaner (even though you’re supposed to use it through the air intake and the engine running, but I just sprayed it on the valves) with pick and air pressure and vacuum.
My question for anyone who might know the answer is:
Is there anything I need to do after I put coolant in the system and bleed the air out? It should start up after putting everything together, right? I’ve heard a couple of people tell me that the car might not start right away because it needs to build pressure and vacuum in the engine, and the fluids need to get to all the places.
Also, my local Mercedes dealer tells me that the engine requires only the coolant they sell, not to mix it with distilled water. Is this correct? I thought our engines require it to be a 50/50 mix.
Any info is helpful as I’m new to being an armature mechanic and don’t want to blow or warp my engine in any way 😂
At the time of cleaning the car has 110,000 miles. The picture above was the worst valve so I decided to use that as a before and after. the valves were super clean compared to other cars with that mileage. I use only Mobil 1 premium fuel and change the oil regularly. So the valves are clean.
the difficulty is not bad if you are DIY savvy. You need to take off the inner cooler, remove the computer (recommended), battery, and intake plenum. You’ll have to replace the intake plenum gaskets when you remove it. Make sure you shut the valves one by one by turning the engine over manually. Make sure you turn it clock wise and don’t turn it counter clock wise.
if you need any help if you’re going to take on that project let me know, I can help as much as I can!
I see, were you the original owner if not what mileage did you purchase the car at?
Update: changed the passenger side motor mount. It was such a pain in the *** to do. You HAVE TO remove the exhaust manifold and the thing above the catalytic converter.
a few of the aluminum coolant hoses from the turbo to the engine had to be removed as well. After pulling off the intake manifold the gasket fell apart into two pieces. So bad to replace that (it’s always a good idea to replace them anyway when removing).
While I had the gasket and exhaust manifold off of the engine, I decided to clean the surface and inside the ports of the engine. Wasn’t needed but might as well.
only thing left to do is put the inner cooler, throttle body, and the computer back in and do the coolant flush/fill.
Well done and we appreciate you listing the steps you took, it should help others that want to perform this work.
thank you for your kind words 🙂 it’s a learning process but I’d never be able to learn if I didn’t go at it. Next job is going to be removing the camshaft adjusters and the chain tensioner and replacing them as my engine had the outdated camshaft adjusters and not the new updated ones Mercedes put out for the M274 engines. So we’ll see how that goes
Curious, what was the reason they replaced it with a new part number? Were their flaws/issues with the older part (for both camshaft adjusters and the chain tensioner?)
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