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1995 SL 320
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19 Posts
Discussion Starter #1
First, what I know...
My garage floor is clean, except for a few oil spots which will be addressed in due course.
I have to add a tad less than a gallon of coolant every four days (or around 400 miles).
I performed a combustion leak test... the fluid remained blue, not a hint of yellow (I have a video of this).
My oil is a clear golden brown, no latte.

Any suggestions as to what to do next? I live in the San Diego area where it costs $86 to fill the tank, making this coolant expense an added insult to injury. HELP!!

2608245
2608246
 

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Registered
1992 Mercedes 300SL R129. 94 S320 Mercedes w140
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34 Posts
Check out the passenger side carpet and floor for wetness. Maybe the heater core is leaking and the carpet is sucking it up. Kinda unlikely with that amount going missing but it is worth a try
 

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Registered
1992 Mercedes 300SL R129. 94 S320 Mercedes w140
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34 Posts
Also, have you tried cracking the oil drain plug to see if water comes out? Again, unlikely as that amount of water would make the oil level show way over full. But, again, you’ve checked the likely places so it’s improbable might just be the ticket
 

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Greek God of the R129
SL500-500SEL-190E
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8,366 Posts
1. Get a new cap.

2. Disconnect the tank overflow hose that goes to the fender tank. You have the new plastic upgraded screw reservoir tank.
Mercedes says, no hose going to the old overflow system.
(Must be disconnected.)

Leave hose hanging loose on the fender side. Or get 2 ' 10mm hose...hook it to the reservoir nipple.
(Somewhere that you can see, the overflow.)

Old system overflow from the bottom tank was going back.forth.
New is not.

The system is self bleeding, you don't need to bleed, just bring the temperature to operating temperature, cap OFF.
Fill the reservoir up to the black/half tank mark.
Close the cap.
Remember you said, no head gasket leaks.
It would be nice to know the year, etc.

Regards,
aam.
 

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M113 SL500
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466 Posts
The anchor on my reservoir holding it to the front bulkhead snapped, leaving the reservoir to jostle about with body and engine movement, eventually causing the top hose port to develop a hairline crack from where I was losing coolant. However, at the rate you're losing coolant, I would thoroughly check around the radiator.

It could also be the heater coil in the washer fluid reservoir.

Since you indicate you don't have oil in your coolant, doesn't sound like a transmission oil cooler problem.
 

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Registered
1995 SL 320
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19 Posts
Discussion Starter #6
1. Get a new cap.

2. Disconnect the tank overflow hose that goes to the fender tank. You have the new plastic upgraded screw reservoir tank.
Mercedes says, no hose going to the old overflow system.
(Must be disconnected.)

Leave hose hanging loose on the fender side. Or get 2 ' 10mm hose...hook it to the reservoir nipple.
(Somewhere that you can see, the overflow.)

Old system overflow from the bottom tank was going back.forth.
New is not.

The system is self bleeding, you don't need to bleed, just bring the temperature to operating temperature, cap OFF.
Fill the reservoir up to the black/half tank mark.
Close the cap.
Remember you said, no head gasket leaks.
It would be nice to know the year, etc.

Regards,
aam.
It‘s a 1995 SL320.
 
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