2015 S550 4matic, 81k

So a few months ago I kept getting a low coolant low warning on the dash vary randomly. When I had it in for an oil change I asked them to see if the coolant was low or leaks and they said both were fine. So I just assumed it was a sensor or something and didn't worry much about it. In the past few months the temperature has never gone above 200 despite the warnings, so again I thought it was just a sensor. Fast forward to a couple days ago, I started to notice the warning was coming on very frequently now when I was driving. But again, no temperature issues or anything. So I finally decided I had to get the dumb sensor (or so I thought) fixed and was just about to get it done. But today I went to go somewhere, and a few blocks away as I'm sitting at a light I see steam coming from front end. I turn right around, go back and park it and pop the hood. I look straight down behind the bumper (there is like a little tray down there or something) and there is fluid everywhere. Can't tell what but assumed it was coolant. I open the reservoir and sure enough bone dry. So I go get some coolant to see if what I suspect happened, that it was a major bust somewhere. It had to be because of the amount of fluid I saw. Yep, I fill it up and within about 2 seconds after I topped it off it all drained out.

Now my initial thought since it is dumping coolant out as fast as it goes in, is a hose came off. That is what would make sense to me but correct me if I am wrong. So tomorrow I am going to go out there and get everything bone dry, and rig up a gatorade bottle with a slit on the top to flip upside down so I can go under and see if I can figure out where it is coming from as it slowly drips. But does anyone know if the hoses are hooked up just like any other car with simple clamps? Or is it different? Can I get to it from the bottom or do I need to do anything else? I'm more doing this in case I have to take it to an unknown shop a few blocks away vs my normal one, and making sure they don't claim there is a problem that doesn't exist. I just want to know exactly what the issue is beforehand. If it is a hose that come off will I be able to see it clear as day? Any insight would be helpful. Am I looking for anything else in particular? (other than the obvious) I just really feel like it is dumping out so much it has to be a hose, but I am far from a mechanic. Thanks.

 

Well if it's just pouring out it should be easy, clamp type varies by location but nothing particularly especial.

 

That makes me feel a lot better, thanks lol.

 

Very common to have cracks in your left side turbo cooling lines. I would bet that's what you have.

 

It’s coming from drivers side behind all these pulleys but can’t see exactly from where. So hard getting good pic or video.

 

I don’t know what is more frustrating trying to fix this or edit a video 10x for it never to upload. Oh wait it worked….

 

I do not think this would be his problem as the Turbo has a separate reservoir. Make sure you fill with distilled water and burp the system, You may not see the leak until it builds a little pressure and the thermostat opens. It can be the cooling lines running to the Wiper Fluid Reservoir.

Make sure to also check your Turbo reservoir as well.

 

Watch the video I posted above. Not hard to see the leak that is for sure.

 

The low temperature circuit is not for the turbo itself, it's for the intercooler.

 

Thank you! Learn something new every day....

 

Check this video out. It is likely the coolant lines to the turbo. Very common problem on the M278.

 

I specifically remember looking at the hoses with the white writing, and the one next to it with the bar code tag and they were at/near the top of the engine, but it is gushing out from way lower. (see video in previous post) Those thin hoses that were right up top in front of you looking down were fine. I wish I would have sen this video before I did it though. I will double check tomorrow because it explains everything I am looking at. Thanks.

 

The turbo coolant hoses are not on the top of the engine. They are about half way down. Right below the thermostat, I dont think you can see them easily from the top. I replaced them on both M278s that I have owned as both engines had failures and while replacing them i also replaced the Themostat as you have to take that off as well. The only things to leak coolant in the area of the videos on the front of the engine is the turbo lines and the water pump. Get an inspection mirror and a flashight and fish it in there and have a look under the themostat and see if that is where it is coming from.

 

Is there any way you can take a look at the 10 second video I posted? It shows it clearly. But if the hoses are lower like you said then it could very well be that. The ones I am talking about were up high. It was very hard to see exactly where the leak was coming from due to where it was, but you can see the area. Very tight with lots going on down there.

 

I did watch it. Those Turbo coolant lines are right above that area the coolant is coming down from. Only way you can find out is the mirror and flash light trick so you can see it with your own eyes. There is too much stuff in the way from underneath to see. Just watch out for the fan when putting the mirror in there if the engine is on. I added a picture of the front of the engine. The area to look is below the Thermostat Housing and above the large crank pulley at the bottom. You will most likley find you leak in that area. Good luck with sorting it out, hopefully it will just be a minor repair for you.

 

Thank you! That is exactly what I found, just can't really make heads or tails of anything from bottom.

 

https://mbworld.org/forums/s-class-w...placement.html
Not a fun job, but can be done at home if you TAKE YOUR TIME!

 

What is the name of the component which is leaking on your engine?