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2004 ML500- Severe coolant leak after mechanic replaced reservoir
Hi, so last 6 months or so my coolant light has gone on maybe once every few months. I would open the hood and see that the coolant was barely below the fill line in the reservoir. Okay, whatever no big deal. I went to AutoZone and bought the Mercedes approved coolant fluid and topped it off every so often. Last week my brake light came on so brought the truck to my mechanics house. He replaced the brake pads and said I needed a new drive shaft as it was rotted and about to fall off, so replaced that too. I told him about the leak- he said he couldn't find any but recommended to replace the reservoir as it looked like it had been repaired in the past, so replaced that as well.
After i got the truck home I popped the hood and took a look at the new reservoir. Looked good but I noticed the fluid level was just below the fill line, just barely. I thought no big deal, maybe he just didn't fill it up all the way. Couple days go by and the light comes on again in the middle of driving. Have barely driven the truck since then just to and from work which is a 60 second drive. Today I finally had a chance to pop the hood and take a took and the reservoir is almost completely empty! I can also see where the coolant is dripping underneath my truck.
Here are pics:
Second pic is where it is dripping. See where it is circled. Does anyone know what that is?
Also, did I do any damage driving the truck with this low level of coolant? It looks like it didn't quite go below the intake so maybe there would enough coolant to circulate? While the light was on and driving, I had been checking the temperature gauge and did not see it go above 80c. If I had been driving with zero coolant circulating, what would happen?
Last edited by wonderbrah; Apr 23, 2021 at 07:51 AM.
In the second photo I do not know what that is. Take more photos and is it on the driver or passenger side?
No, not leaking from clamp. Second picture is some kind of rubber grommet that it was dripping out of. There's one on the passenger and drivers side. The one that the leak was coming out of was on the passenger's side. I will take more photos.
To me I would say that there is a leak coming from the radiator and the hose does not look wet.
Okay, thanks. Do you think I did any damage driving like this? I didn't notice any smoke, no signs of overheating. Temperature gauge was within normal limits.
Turn the key to the on position and see if all those light bulbs light up.
Oh, no the coolant light did come on. I drove it a day before I took the pictures in the original post. So there likely was a bit more coolant in there then you see when I last drove it but the light was on.
My mechanic said it's the drain plug. The drain plug is leaking and I will need a new one
Yes, there are many manufactures and each one has a different plug.
Did he have to drain the coolant for any reason?
Ask him to show you where this leak is and take a photo of it.
Yes, he did. I have been dealing with an almost negligible slow leak causing me to top off the reservoir every few months. He said it looked like it the reservoir had been repaired in the past so he recommend replaced the whole thing. So he did and also flushed the coolant and refilled it.
I mean, I already took a picture of the leak, no? Isn't that the drain plug? That's where it is dripping out of
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