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ML500
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Discussion Starter #1
I opened the hood of my 2004 ML500 today to add some more windshield washer fluid and noticed a green fluid on the belt and pulleys in my engine compartment. I first though it might be my water pump going, but I don't use green anti-freeze. I use the genuine MB clear fluid, and the clear color is what is in my reservoir. I then did some searches on this forum and couldn't really find much else that might explain this fluid color or where it might be coming from. I found one reference to some other Mercedes models using an alternate green ATF fluid, but the fluid I use for my transmission is a bright red color. I in fact had a tranny flush done this summer, and I know the fluid that was replaced was the genuine red stuff. I checked it with the dip stick tool that I have after the flush was done. I checked all the other fluids today, and they were as expected. All of them had the right amount and were the colors they should be. The only fluid I did not check today was the tranny fluid, since I am traveling right now and don't have the dipstick tool with me. I am therefore at a loss to what might be the issue. I have had no issues with car, no indicator lights come on, no problems with the transmission, or anything else for that matter. The car has been working fine. Does anyone have any ideas on what might be going on? I know there are various fluids that get cooled through the radiator, and I am thinking the leak might be with a fitting at the radiator. I would appreciate any help you can give me.
 

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ML 350 CDI
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It would have to be a coolant related issue. I would keep a close eye on the reservoir for level going down.

Trans fluid is an oil, so it will feel like it. If you run some of the green liquid on your fingers and it is not a lubricant then it's either coolant, or you've started the engine while an alien has been inspecting the front of it. See if you can also find one of his arms......:D
 

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Zotye Auto 1.5T T600 2016
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Taste the fluid, if it is sweet then it is coolant and if not it is an alien.
 

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Zotye Auto 1.5T T600 2016
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^Not if it tastes sweet;)
 

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Discussion Starter #8
Okay... I looked for the aliens and couldn't find any. As I examined the fluid more tonight, I noticed there seems to be a high concentration of it on the water pump. If my coolant is clear though, I am still having trouble buying that the issue is with the water pump. The fluid forms a thin layer on the pulleys and when I feel the fluid, it feels oily. However, the engine compartment is not exactly clean and was somewhat greasy and oily to begin with. Therefore, it is hard to tell. When I pour water on the pulleys, some of the green fluid washes away, so it could just be that some of the green fluid is sticking there because the pulleys were a little greasy and oily to begin with. I guess my question then is if it is the water pump, why is the coolant green? Could there be some chemical reaction going on to cause the fluid to change colors? I don't hear any noises from the water pump area, so I am wondering what else I can do, if anything, to know if that is indeed the issue. I may just have to wait and see. My previous experiences with water pumps is that they make a loud noise. You know they are going to go. I did check the power steering fluid again, and it is brown. Since I cannot check the tranny fluid right now, I don't know if this turned green on me. Can the tranny fluid break down enough to turn green? It seems highly unlikely this would happen, especially given then fact I had a tranny flush done this summer. I assume the two lines at the bottom of the radiator are for the tranny fluid. Can anyone confirm this?

I am hoping someone might know enough about the fluids to know how they change. I guess I could call the Mercedes help line tomorrow. I have called them in the past on things and sometimes have gotten pretty knowledgable people that will research items like this for me. It usually takes a while though. Thanks for your help.
 

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Zotye Auto 1.5T T600 2016
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Is your coolant green and is it low? Transmission fluid is red or neutral in colour and yes the two lines to the radiator are for the transmission cooler. Pumps do not always make a noise when they pack up. Fluid will leak through the small hole at the base of the pump.
 

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ML500
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Discussion Starter #10
The coolant is clear. It is the Mercedes-Benz genuine coolant. Right now, the coolant reservoir is not low. It was a little low about a week ago though, but I filled it back up. I know the water pump may not always make a noise when it is going, but I guess what I can't get over is the fact that the color is green and the coolant is clear. I am just not wanting to go to all the work to replace the water pump, when it may not be the issue.
 

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Discussion Starter #11
http://www.benzworld.org/forums/w220-s-class/1334450-green-transmission-fluid.html

I found this post about green transmission fluid. I guess I could slightly pull the tranny pan plug and see if any green fluid leaks out. I won't be able to do this though for a few days. It could just be his car had an alternate ATF fluid. Can the fluid break down enough to change colors into green? I wonder what would cause this?
 

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Zotye Auto 1.5T T600 2016
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ooppsss, you had better check it soon, transmissions are not cheap.
 

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99 White ML320, 13 Audi S5,84 300ZX Turbo, 03 Audi A4, 03 Audi TT, 65 Ford Galaxie Conv
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I lean witek's direction. Green due to dye in the refrigerant. You never said whether you have tried to run the A/C to see if it gets cold.
 

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2002 ML55 AMG, 2005 Chrysler Crossfire Coupe Limited, 1999 C280
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^^I agree with lyleswk and Witek's suggestion earlier on.

It may well turn out to be air conditioning refridgerant dye - It's usually green in colour and bitter to taste.
 

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ML500
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Discussion Starter #15
I haven't used the AC in a while. It is 30 degrees today and snowing. I do know the heater works fine. :) This would make a lot more logical sense though. I may have a crack in the line somewhere. I will check this out and post back what I find out.
 

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99 White ML320, 13 Audi S5,84 300ZX Turbo, 03 Audi A4, 03 Audi TT, 65 Ford Galaxie Conv
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:1poke: By the way, everytime I see someone talk about tasting fluids from their car, I just have to go :eek:. Whiskey, no problem. Coolant? PS Fluid? Refrigerant? Not me :)
 

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2004 SL500; 2003 E320; 2001 ML430 Sport; 1999 E320 Wagon
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Not all advice here is good. Speaking from experience however, coolant (ethylene glycol) tastes sweet. It is also deadly, especially to dogs who will gladly drink an entire pail of it when left unattended on the floor.
 

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99 ML320 2000 ML55 AMG... miss my 84 500sec AMG
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im glad someone said it! i wanted to but didnt want a firing squad looking at me..... i said when i read some of these replys , taste it? no way!
 

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1999 ML320 Elegance, BMW R1150RT, SAAB 9-3
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282 Posts
ok so, is this right?

green stuff under the hood taste test:
if engine coolant, then tastes sweet
if A/C refrigerant, then tastes bitter
if alien, then takes like chicken!
 

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how about we see some pictures of the fluid and where it was found, so we can make a bit more educated guesses. Since the OP said he uses OEM cooland, which is yellow, I dont care how worn out or dirty it may be, it wont be green. My bet is on the power steering fluid, which actually turns greenish after a while, and its most likely coming from the reservoir to pump seal or the low pressure return line if the mileage is high.
 
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