What is this green fluid? - PeachParts Mercedes-Benz Forum

sokoloff · #1 06-05-2016, 10:15 AM

Had my car out of commission with the belly pans removed for about a month. When I got back under it, I see about a three inch diameter puddle of green fluid under the left side of the engine toward the rear. It had an oily feel. It's not the right color for Mercedes power steering fluid and it's not the right color for coolant (using Zerex G05). What could it be I wondered? It kind of looks like the AC dye I added over four years ago. The AC system was repaired four years and 40,000 miles ago. Could I not have noticed it in all that time and the four oil changes since? And could there still be enough of a drip after all that time to mark the garage floor - that I doubt.

Your ideas appreciated. BTW the AC is working great and the numbers seem to indicate everything is fine. See two photos below of my current concern and one from four or five years ago when I saw where the AC dye was coming out.

ROLLGUY · #2 06-05-2016, 10:48 AM

Looks exactly like A/C leak check dye. The best way to know for sure is to use ultraviolet light and glasses to see if the green area glows. If it does, you have found what the substance is. The next step is to clean the area real good with degreaser, and then look again with the light and glasses. You should then be able to see exactly where the green stuff is coming from......Rich

jay_bob · #3 06-05-2016, 11:31 AM

Or just hit it with a white LED (flashlight or phone) or a fluorescent trouble light. There is enough UV content in these sources to light up the dye.

sokoloff · #4 06-17-2016, 12:34 PM

Okay, cleaned it all up and took a nice long drive and the green fluid/dye is there again. Hard to see exactly where it is coming from, but it is collecting on the underside of the compressor. So here are my questions.

1. The AC is working just fine, getting about 40 from each side.
2. Car is rarely used anymore, but I'd hate to have to make a trip in really hot weather and not have AC. Any guess as to how long I might be able to go on like this? Will my vent readings begin to rise showing that the system needs some help?
3. Think I can nurse it along for awhile by adding a little r134a when/if needed?

leathermang · #5 06-17-2016, 12:40 PM

I would first carefully see if I could tighten the actual joint from which it is leaking.. clean well again...turn on short period... use mirrors and lights to see it this is just one joint...or if it is a seam in the compressor for instance... or the front of the compressor under the clutch... you really need to narrow down the leak as close as you can before making any other decisions or assumptions...

Zulfiqar · #6 06-17-2016, 01:54 PM

looks like the variable valve in the compressor is leaking, might want to ask around for the O rings for it, its the updated style denso unit you have.

Do not remove that snap ring without discharging the unit first.

Maxbumpo · #7 06-17-2016, 03:13 PM

Looks like the compressor is leaking oil, maybe not the refrigerant gas so much. Lack of oil will eventually destroy the compressor. Discharge the system, remove and re-seal the compressor (ALL the seals, not just the leaker) and replace the receiver/drier. Vacuum, pressure test for leaks, and re-charge with correct amount of oil and refrigerant.

ah-kay · #8 06-17-2016, 03:46 PM

It may be the high pressure hose. I had the same problem, I thought it is the compressor leaking but it turned out to the the high pressure hose. Clean everything all up and wrap some kitchen towel round the HP hose and turn on A/C for a while. I bet the kitchen towel will be soak with the green oil. Give it a shot, nothing to lose.

sokoloff · #9 06-17-2016, 07:58 PM

Thanks for the replies guys. I will do a little more investigation or get it to someone who has more experience than I do. At least it's good to know that I didn't miss that leak through four years, four oil changes and 40,000 miles. I guess it says something for getting under your car and looking around once in awhile. I use suction to get most of my engine oil out, but always drain the last little bit out the drain plug and take a look around.

sokoloff · #10 07-26-2016, 05:36 PM

Okay guys, I had my middle noise encapsulation panel off for a couple of months so that I could observe this leak. Got under there again today to see what was going on. Small leak still there and it appears to be coming out of what Zulfiqar I think calls the variable valve of the compressor. See attached photo. There doesn't seem to be any wetness above that point and the valve itself is in a slight depression and there was some wetness in that depression where gravity and driving wouldn't easily allow it to gather, so I'm pretty sure that's the issue.

So my next question is how to fix it. Can it be done with everything in place from underneath after the system is evacuated? Can the valve be tightened in place? Where can I get the O ring for it? Doesn't seem to show up in the EPC. In fact the valve doesn't show up at all as far as I could tell. Can any good AC shop handle the job? I've got a dealer I trust and have no issue taking it there, although it is a little inconvenient.

Suggestions appreciated.

leathermang · #11 07-26-2016, 05:48 PM

Some compressors have ' high pressure blow off valves ' ... that sure looks like one..
so someone should be able to tell you how to fix it.. with the system evacuated I feel sure it can be fixed in place...

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