Hello,
I would not have thought that my first post here would be at 50k miles, but here I am.

After returning from a trip in my C-Class RV, I noticed a couple wet marks on my driveway under the engine. After looking underneath, I noticed they were from coolant dripping off the bottom of the oil pan. The entire pan had coolant on it, with heavier coverage on the front than the back - see first two attached images and video.
No evidence stuck out to me that it was from a failure related to the lower radiator hose. Plus, I can't see how a failure would result in coolant collecting on the bottom of the pan.
Upon closer inspection, it seems like the leak is coming from above this area. Tracing an (assumed coolant) leak path, I land in the area of the water pump pulley (see 3rd attached image and 2nd video. I was unable to confirm it's coolant (rubbing my finger on it and smelling them did not smell of anything coolant-related, I wonder if after a certain point of drying it loses it smell?). The RV has been sitting for at least a week now and this assumed-leak area is still wet.

Does anyone have an idea where it's coming from / what the issue could be?



suspected coolant leak from water pump pulley area.

(1st video: leak on oil pan viewed from underneath vehicle)
(2nd video: suspected leak from pump viewed from above engine looking down between engine and radiator fan)

 

Keep in mind the cooling fan blows any coolant in the front area to the back of the engine.

It does appear from the pix to be a leaking water pump. You can verify if you remove the belt and pulley from the water pump. To replace the pump you will need to remove those parts anyway.

 

Thanks for the reply. This will be my first crack at doing anything with a water pump. While investigating, are there specific areas on/around the pump I should focus on to verify?

 

Hi,

I'm following up to bring closure to this thread as I found the source of the leak - the water pump.
The first three images attached lead me to confirm the water pump - First two images show dark stains on both sides of the water pump, which led me to examine it more closely. The third image shows coolant present behind the pulley / underneath the pump.

My E-350 has 50,000 miles on it. I am very surprised it failed this early. My only guess as to why is, I recently drove back from Florida taking country roads which kept me at 60mph, or more importantly, ~2100rpm. At this RPM I would get a resonance squeaking noise from the serpentine belt (I've fixed this squeak by adding the missing/deleted idler pulley). I wonder if the belt's resonance forces caused the pump's seal to fail prematurely? In fourth and fifth images you can see a black and yellowish mark/stain on both the pump and the block. I'm not sure what this is, but I'm guessing this is the failure point. Any idea folks??

 

Certain components in the green anti freeze played a role in deposits that were not good for water pump seals and that was one of the reasons for regular replacing certain anti freeze on a scheduled basis. The anti deposit components became depleted and replacement was suggested. Now you know this ,so water pump problems should ?? be a thing of the past, lol.

 

This was at 50k. Maintenance schedule states to change it every 105k!

 

I would also consider changing to a long life anti freeze coolant.
The green stuff was a cause for clogging radiators with solder bloom.. Looked like calcium deposits.