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My 2014 E63 S is using what seems like a lot of coolant. I purchased pre mixed 50/50 from the dealer when I got the warning that is was low about a month ago.
After a long drive like 300 miles round trip - the car needs more. I see visible coolant on the reservoir - but it just doesn't add up to the amount it's using it seems like. Is it evaporating out through the leaky reservoir or possibly somewhere else. There's never coolant on the floor of the garage, so I know it isn't the radiator or hoses.
Any ideas besides the obvious, replace the reservoir?
check behind the driver side cylinder head... theres a fitting that cracks along with a hose.... it sprays into that absorbent like bulkhead material and does not make it to the garage floor.... this just happened to me. When its actively leaking you can smell it and see steam back there.
this video shows wshow happened in my case
https://youtu.be/H7YmGOinRjg?si=AUfragExqMco-Ylj
Last edited by MerchantM5arine; Nov 18, 2023 at 01:58 PM.
I'd probably start with the reservoir by the looks of it.
it's definitely going in for that. If they find something more serious, I guess the question will be whether to cut my losses and trade it before it blows up.
The reservoir forms a hairline crack and because the system is pressurized it will spray out in a fine stream and it's hard to see with the naked eye unless up close.
The reservoir forms a hairline crack and because the system is pressurized it will spray out in a fine stream and it's hard to see with the naked eye unless up close.
Replacing the reservoir is step 1.
Ordered new reservoir and cap from FCP Euro. Should be here next week. Now I just need to find a solid DIY video. Many out there - just not seeing the proper bleed technique, which I assume I need to do as well correct? Should I flush the whole system or can I get away with just a reservoir replacement?
Actually I don't know. Is it perhaps due for coolant anyway?
It also doesn't have to be totally empty to vacuum fill.
you would think the XENTRY procedure is floating out there somewhere. I ordered a MB compatible vacuum fill tool from ECS tuning. I'll give er the old college try when all the parts come in next weekend. Will report back. Anyone else feel free to chime in before I get wrenching.
To do this, drain about half the coolant from the bottom of the radiator so that the coolant level is below the bottom of the reservoir and the reservoir is dry. No need to completely drain the system. Catch the coolant in a clean bucket.
Then you can disconnect the reservoir and replace it. Once the new part is in place, refill the coolant through the reservoir opening using the old coolant and turn on the engine (with the reservoir cap off) so the system can bleed itself. The coolant level will drop as the system bleeds itself. Top the coolant off once the engine is up to temperature. Put the cap on the reservoir and drive it around to see if that solves your loss of coolant problem. If that fixes the leak, then you can decide whether to drain the system and put in new coolant. If you haven’t replaced your coolant in the last 30,000 miles or so, I’d replace it.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Generally, I recommend doing an engine block test whenever I hear of a coolant problem. Loss of coolant can be anything from a cracked reservoir to a blown head gasket to a pipe leak elsewhere or to a cracked head -- hopefully this is just a reservoir problem. But, I would definitely check the block if the problem persists.
you would think the XENTRY procedure is floating out there somewhere. I ordered a MB compatible vacuum fill tool from ECS tuning. I'll give er the old college try when all the parts come in next weekend. Will report back. Anyone else feel free to chime in before I get wrenching.
Get it pressured tested and block tested to make sure no headgasket or cracked head issues are present. The pressure test should show a leak. Look everywhere. Take off any splash shields and investigate. I have seen reservoirs, plastic coolant pieces, even radiators and orings leak. You will find the leak. Fix it asap. I’m currently dealing with a leak in a hose for the secondary cooling system. Keeping these cars in shape is a lot of work.
All fixed up. Car pressure tested fine. New reservoir is on. The radiator vent hose was bad as well. Coolant is holding level fine. Luckily just a reservoir and hose it looks like. Thanks all for the help.
Looks like I’m experiencing the same thing on my 2015 E63S. I happened to look back there and see some moister. I also noticed some “steam” come from the hood on the driver side by the window. Do you know what exactly the fitting or connector is called? Thanks for the help
Looks like I’m experiencing the same thing on my 2015 E63S. I happened to look back there and see some moister. I also noticed some “steam” come from the hood on the driver side by the window. Do you know what exactly the fitting or connector is called? Thanks for the help
You need to check out my thread(s) about the cooling system. Where you are talking about sounds as if the hoses from the rear of the engine to the heater core has failed, the coolant temp sensor is there as well - another known cause of leaks. The threads are VERY in-depth.
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