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2006 E500, 2013 S550 and a retired 88 SDL
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Discussion Starter #1
My diesel has been losing coolant from the system at about a liter a day.

It has been raining all week so I have not noticed the area where it has been leaking under the car.

When I've filled it, I have not noticed any oil in the fluids, I understand that the high compression diesel engine pushes into the cooling system, rather than having coolant in the oil like a gasser with a gasket leak or head crack.

Fortunately, I live in Minnesota where its been in the forties and having the heater/defrost on keeps the temp at just above 80. As it get warmer I will be very concerned.

Does anyone have any experience or knowledge about coolant loss in the 300 SDL?
 

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First you need to determine if it is leaking or being burned.

After the car sits overnight is their pressure in the upper hose? That is extremly bad and would point to a cracked head.

It could be a head gasket does the exhuast smell sweet?

Any strange temperature changes? Ie is it running at its normal temp?

Has the car ever been overheated?
 

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2006 E500, 2013 S550 and a retired 88 SDL
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424 Posts
Discussion Starter #3
The leak was coming from the upper hose, a small crack was shooting a stream into the hood cover just enough to soak it in.

Very odd, thats why there was no discernable pool on the ground the coolant would dry from the heat of the engine.

However in replacing the hose I found a black sludge coat inside of it. Is this common, I think that a radiator flush is the first step but I might have other issues pending. Any comments?
 

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2006 E500, 2013 S550 and a retired 88 SDL
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424 Posts
Discussion Starter #4
Thanks for the reply Hatteras,

As far as overheating, the car has never been past the 120 mark. Although I have seen it up there on about 3 occasions in 3 years. Always under hard acceleration with the A.C. running. As soon as I turn on the heater and slow down the temp goes into the 80-90 range.

There did not seem to be any pressure remaining in the hose after I shut the engine off the, the crack was right on top and obivious when the engine was running- a pinpoint stream of antifreeze. With the engine off no evidence- so no pressure.

I'll be on the look out for the symptoms you mentioned.
 
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