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Rocinante440 · 12-08-2022, 08:53 PM

Ok, I'm puzzled and mildly concerned. When I lifted the hood today on our 2016 Sprinter 3500, I noticed a small open-ended rubber hose that comes out of the left side of the engine via some kind of thing, over near the dip stick, and had positioned itself perilously close to the cooling fan. After looking around a bit behind the antifreeze bubble, connected to a larger hose, likely for coolant, I saw a clip there that was suspiciously similar in size to the OD of this little open-ended hose. So I clamped it there. It's still open-ended, not connected to a darn thing. The engine is running fine, and blocking the end of the hose with my thumb for a few moments has no effect whatever. So, What the heck is this hose for, and should I be worried about it? Pictures attached. Sorry if I'm not very clear in this description, but I'm definitely not a mechanic - I'm just not used to seeing rubber hoses under the hood that aren't connected to anything, and I expect that to be a problem vs. a feature.

donr103 · 12-08-2022, 09:55 PM

Looks like vent hose for trans or diff box.. when oil in gear boxes heat up.. the air expands.. and you need a vent.. because manufacturers worried about hi water.. like driving thru a storm.. many times they run a hose up hi.. to keep storm water out.. so looks normal to me.. but I am not a Mercedes mechanics .. but imho that is ok.. no worries.. easy to double check.. if you want.. follow hose down.. and see if comes off one of the gear boxes.. like diff.. transfer case or top of trans..
Good luck and keep us posted

AudiDudi · 12-08-2022, 10:46 PM

Might be the fuel filter water drain hose. Hard to tell from the pictures, What is the other end attached to?

TandW · 12-09-2022, 07:58 AM

Quote:

Originally Posted by AudiDudi

Might be the fuel filter water drain hose. Hard to tell from the pictures, What is the other end attached to?

X2.

Rocinante440 · 12-09-2022, 06:34 PM

I don't know what the gizmo is called that the rubber hose is attached to. It's pictured in the photos. There's a braided hose coming out of something in the engine that goes into that gizmo. The disconnected rubber hose comes out of the other end of the gizmo. Here are photos with the interesting parts called out in red. Sorry I didn't do that the first time. As the first response suggested, I'm hoping this is nothing to worry about.

Winterbagoal · 12-09-2022, 06:43 PM

Maybe try searching on the partially visible part number in the picture, if you can get the whole number. What it is might give you a clue as to what the hose is for. Sorry, best I can do.

bigb56 · 12-09-2022, 06:53 PM

As mentioned it is your "water in fuel" drain hose. On the OM642 in the Sprinter they decided we needed a separate, remote mounted drain valve as shown in your last picture. The water in fuel line connects to the top of your fuel filter via the easily breakable white clip then travels toward your oil fill tube mostly hidden where it emerges and connects to that small plastic valve which is attached to a metal bracket and fastened to the engine. Then the hose in question connects to the front of this valve and is routed to the right headlight where it is stored in clips around your right side headlight area so it can be easily removed and placed in a container to catch the water/fuel when you open the valve. Many have broken the small white clip and believe it or not if this happens you have to buy the entire assembly $$$ as the clip is not sold separately. You are dead in the water as fuel will pour out of the top of the filter. However there is an easy fix if that were to happen, you don't really need that extension. Every new filter comes with a small valve in the box that you can screw into the top of the filter and eliminate the whole thing. If you ever need to drain off water you just reach under the air box and push a small hose onto the little valve and turn it counter clockwise to drain. You can store your small hose in the headlight clips. I carry one of those filter mount valves in my spare parts in case this happens to me it will mean the difference between dead in the water vs back on your way in 5 min.

edit: looking at your hose it may not have the headlight clips like mine, it looks to be too short and it may just reside exactly where you put it.

AudiDudi · 12-09-2022, 09:11 PM

Quote:

Originally Posted by bigb56

As mentioned it is your "water in fuel" drain hose. On the OM642 in the Sprinter they decided we needed a separate, remote mounted drain valve as shown in your last picture. The water in fuel line connects to the top of your fuel filter via the easily breakable white clip <snip>.

OFC the clip broke when I did mine. I just made a clip from a paper clip and it is working fine after 2100 miles.

donr103 · 12-09-2022, 10:42 PM

Oops.. looks like I missed this one..
Good luck and keep us posted

bigb56 · 12-10-2022, 09:34 AM

Quote:

Originally Posted by AudiDudi

OFC the clip broke when I did mine. I just made a clip from a paper clip and it is working fine after 2100 miles.

I've heard of people making a clip, there is also a clip available in a package from the "Help" line that is made for some Ford application but works on the Sprinter fuel line although not exactly like the OEM Mercedes clip. I find that a little heat on a plastic connector goes a long ways in keeping it from breaking when disassembling.
It would be wise for you to carry one of those screw in valves that come with a new filter just as a precaution.
Incidentally when they change the filter at the dealership they don't unclip the line, they reach under the 90 degree connector and unscrew the nipple from the filter which spins freely in the 90 degree fitting. I'm sure they learned this trick after breaking a few clips.

AudiDudi · 12-10-2022, 10:18 AM

Quote:

Originally Posted by bigb56

I've heard of people making a clip, there is also a clip available in a package from the "Help" line that is made for some Ford application but works on the Sprinter fuel line although not exactly like the OEM Mercedes clip. I find that a little heat on a plastic connector goes a long ways in keeping it from breaking when disassembling.
It would be wise for you to carry one of those screw in valves that come with a new filter just as a precaution.
Incidentally when they change the filter at the dealership they don't unclip the line, they reach under the 90 degree connector and unscrew the nipple from the filter which spins freely in the 90 degree fitting. I'm sure they learned this trick after breaking a few clips.

Good info - I do carry a spare paper clip

My OEM filter did not come with a valve.

Rocinante440 · 12-10-2022, 10:24 AM

Quote:

Originally Posted by bigb56

As mentioned it is your "water in fuel" drain hose. On the OM642 in the Sprinter they decided we needed a separate, remote mounted drain valve as shown in your last picture. The water in fuel line connects to the top of your fuel filter via the easily breakable white clip then travels toward your oil fill tube mostly hidden where it emerges and connects to that small plastic valve which is attached to a metal bracket and fastened to the engine. Then the hose in question connects to the front of this valve and is routed to the right headlight where it is stored in clips around your right side headlight area so it can be easily removed and placed in a container to catch the water/fuel when you open the valve. Many have broken the small white clip and believe it or not if this happens you have to buy the entire assembly $$$ as the clip is not sold separately. You are dead in the water as fuel will pour out of the top of the filter. However there is an easy fix if that were to happen, you don't really need that extension. Every new filter comes with a small valve in the box that you can screw into the top of the filter and eliminate the whole thing. If you ever need to drain off water you just reach under the air box and push a small hose onto the little valve and turn it counter clockwise to drain. You can store your small hose in the headlight clips. I carry one of those filter mount valves in my spare parts in case this happens to me it will mean the difference between dead in the water vs back on your way in 5 min.

edit: looking at your hose it may not have the headlight clips like mine, it looks to be too short and it may just reside exactly where you put it.

Thanks so much for this detailed info. I really appreciate it. I'll look around to see whether there's a white clip as described that I should be using instead of the one I found as shown in the picture. Given what you said happens if the hose droops down toward the ground, I'm pleased to have found a clip that holds the tube at an upward angle do it won't drain unless I un-clip it and so on. (Edit: I now see from the videos below that fuel won't come out this hose unless I open the valve as shown, but still - if I ever need this hose, I want it where I can find it.

)

BTW, I did try to do a search on the partially visible part number on that component at the engine and came up empty, but now that I have a handle on the purpose of that disconnected hose end, I'll look again for my own edification.

Rocinante440 · 12-10-2022, 10:27 AM

Voila! YouTube shows how it works. My drain hose is clipped in place exactly as shown in the second video below. I might gently tie it into place with a zip tie to ensure it doesn't flip out of place again and it will stay where it's supposed to be until that fateful day if I get a "water in fuel" warning. If I do, I'll know exactly how to fix it. Thanks again!

https://www.youtube.com/watch?v=HhmI0tuOSx4

https://www.youtube.com/watch?v=ieZGgGIJp6w

bigb56 · 12-10-2022, 10:28 AM

Quote:

Originally Posted by Rocinante440

Thanks so much for this detailed info. I really appreciate it. I'll look around to see whether there's a white clip as described that I should be using instead of the one I found as shown in the picture. Given what you said happens if the hose droops down toward the ground, I'm pleased to have found a clip that holds the tube at an upward angle do it won't drain unless I un-clip it and so on.

BTW, I did try to do a search on the partially visible part number on that component at the engine and came up empty, but now that I have a handle on the purpose of that disconnected hose end, I'll look again for my own edification.

The white clip I mentioned is on the filter in the center of the engine, not where you store the drain hose. The clip you put your drain hose on looks to be the right one.