What is this under the coolant bottle?

Red Eye

New member
While changing my transmission oil, I moved the coolant tank over a bit to help pouring in the new tranny fluid down the dipstick pipe.

I had to scratch my head about two things.

One, a black rubber hose looped up and back down, not attached to anything. (shown by the red arrows). The hose seems fatter at one end, but it is not, it is just closer to the camera. What was it or should it be connected to? Looks like a vent hose, but what is it venting?

What is it.jpg

Two, the coolant lines connect to a metal block forming the letter H. (shown by the yellow arrow) One arm of the "H" is blocked off. No wires, or controls or sensors go to this block.

Any one know or have something similar? or is this just one of the mysteries in life?
 

Boater

New member
Different year to mine I reckon :D: The moveable coolant tank gives that away, mine is built in to the radiator, although we are about in the area where the screenwash tank goes?

Pipe with no connection could be a vent from the coolant header tank, look for a small spigot with nothing attached. The free end should presumably lead somewhere safe to drip overflow coolant, mine just stops about half way down the front of the radiator, still it is below the sensor wiring so maybe it meets that requirement.

The doohickey in the heater lines is a bit of a mystery, firstly because your heater lines are arranged differently to mine!
With the sprinter heater matrix mounted so high, I believe one hose has a non-return valve in so you don't lose the water from the matrix every time you stop - this may be related?
Alternatively since it is on the flow and return maybe it is a thermostatically operated bypass, denying hot water to the heater when the engine is too cold? I'm thinking it would work like the main engine thermostat and not require any external connections.
If it is a thermostatic bypass it adds another possibility to some of those questions about odd heater behavior - could be down to thermostast opening and closing at wrong temps.
 

Red Eye

New member
Thank you boater. That makes sense to me.

Here is another picture showing how one arm of the H is blocked off with a plug and clamped.
do hicky.JPG

I'm guessing that other models of Sprinters would have this mystery port going to somewhere.
 

sprintguy

16+ yrs Master Commercial technician
first of all the little hose is for the fuel/water drain , that attaches to the open and close valve just above the trans filler pipe. no big deal to be hanging there. As for the coolant manifold ... that would be were the block / coolant heater would go if the vehicle had that option.



Carl
 

jdcaples

Not Suitable w/220v Gen
first of all the little hose is for the fuel/water drain , that attaches to the open and close valve just above the trans filler pipe. no big deal to be hanging there. <snip>
Carl

I think this is where it goes.jpg


The blue marked hose end goes on the nipple of that round thing I've pointed at in blue. Then you twist the round thing, which opens the valve. If you have water in fuel, the in tank lift pump pressurizes the filter and water comes out. If you're environmentally conscious, you put a bottle at the low end of the hose and dispose of the liquid in a responsible manner.

The lift pump pressurizes the tank side of the filter for 30 seconds in ignition key position two (or is it three? - whatever just before "start"). I doubt there'd be any water in the filter housing after two cycles of 30 seconds and you'll need a bottle that holds at least .5 litres.

I think this is correct. Make sense?

-Jon
 

Red Eye

New member
Sprintguy and jdcaples, thank you so much.

the hose fits like a glove, loops up and gets the crap away from the engine block. I could see it was disconnected for a long time, all grimy.

In two seconds, a nice tight fit on there now everything looks good.

It always drives me nuts and bothers me when something is dangling or amiss, until it is taken care of...... so now I'm happy.

I would have never guessed.

Thanks for going out of your way to help.
 

jdcaples

Not Suitable w/220v Gen
Just a note about that hose being disconnected for a long time and being grimy. Mine came from the factory disconnected as well. If I hadn't connected it, mine would have been in the same place as yours. This is a manufacturing issue, not a design defect and not an artifact of prior ownership neglect.

-Jon
 

mofo989

Member
While changing my transmission oil, I moved the coolant tank over a bit to help pouring in the new tranny fluid down the dipstick pipe.

I had to scratch my head about two things.

One, a black rubber hose looped up and back down, not attached to anything. (shown by the red arrows). The hose seems fatter at one end, but it is not, it is just closer to the camera. What was it or should it be connected to? Looks like a vent hose, but what is it venting?

View attachment 50355

Two, the coolant lines connect to a metal block forming the letter H. (shown by the yellow arrow) One arm of the "H" is blocked off. No wires, or controls or sensors go to this block.

Any one know or have something similar? or is this just one of the mysteries in life?


Ha Ha! I was just looking at that the other day and was planning to post the same question. Mine is also not connected to anything on either end!
 

Boxster1971

2023 Sprinter 2500 144wb AWD
During my last fuel filter change at MB dealer they disconnected this line at the fuel filter because they couldn't get it to stay connected to fuel filter water drain connector. They claimed it was part of a MB service bulletin.


Sent from my iPad using Tapatalk
 

lindenengineering

Well-known member
For info
The plastic hose assy costs about $58.
There is a conversion which caps the thing off at the filter head. We simply still use the original plastic pipe as a replacement when the holding claws get broken by age/heat etc.
It can be a fire hazard so be aware. Extra attention is needed when changing out the filter!
I once bought a burnt 2009 Sprinter due to that pipe sheering off during a summer and the whole plot went Woosh! Up in flames.
Dennis
 

smiller

2008 View J (2007 NCV3 3500)
What a coincidence! I just yesterday noticed that hose sitting there not connected to anything on either end and wondering what it was (on a 2007 FWIW.) The last fuel filter I bought came with the alternate cap that requires access to the fuel filter to purge water, but also eliminates the drain pipe, the OEM cap with the clips that always break, etc. Since I have never needed to purge water out of any diesel vehicle I have ever owned I think the chances of a leak outweigh any need for the external drain line, so I will be eliminating it at the next filter service.
 

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