A140 Pipe in the battery enclosure

[Kaiman]

I have had some problems related to the central locking on my wifes 1999 A140. I took the battery out to see if that would reset anything (It didn't).

A couple of things worried me.

Firstly there was water in the battery and fuse enclosure. That cant be good. I did drive through some terrible rain and some flooding on Saturday, but I cant imagine how water would get there except that there are two threaded holes in the base of the battery compartment, should I fill them in?

The second one is that when I took the battery out, I discovered a clear pipe with a black tube connector on the end seemingly doing nothing. What is that for?

Any advice gratefully received.

 

[Kaiman]

Update.

A bit of reading tells me the pipe is a battery overflow pipe, so I am assuming the liquid was battery juice as the pipe is disconnected.

Is that about right?

 

[bigasotonuk]

Hi,
Is the battery secured in the battery box by a bracket? If not it could be for that.
If it is secured, it could just be that they are additional battery bracket holes for a different sized battery fitted on a different model "A" Class.
The pipe sounds like a breather pipe for the battery look at the top edge around the battery there should be a hole where it just pushes in.

 

[Ellsy Tanners]

What comes out of the battery drain off tube is normally very corrosive, i would imagine it has just got in as you say through the bolt or wire grommets to the side. its not uncommon to find a small amount of moisture in there. I had one in this morning with the same.

Its even possible it is spilt top up from when checked on the last service. mop it up and keep an eye on it, i very much doubt you have anything to worry about.

but make sure the drain off is installed as a leak of battery acid can cause damage.

 

[Ellsy Tanners]

Another thought, the battery should be held in by a white plastic handle type bracket with two 13mm retaining bolts on both sides. Have you got this?

 

[FIBAMAN]

The pipe is primarily to vent gas (hydrogen) from your battery cells, produced during charging. Hydrogen is very explosive when accumulated in the right concentrations, this is why we are told not to smoke when working with batteries. It also acts as an overflow but I would guess you will have to try pretty hard to overfill that much.
If your battery is Merc original then there should be a connection spigot near the top of the battery, if not then the battery may be an aftermarket replacement, if it is then ensure that it is sealed type.

 

[Dec]

As has already been said, the tube is for venting gases from the battery, the plug on the end of the tube plugs into the hole. There will be another vent hole, at the opposite end of the battery, it should remain sealed.

Dec

 

[mattkh]

If your battery is Merc original then there should be a connection spigot near the top of the battery, if not then the battery may be an aftermarket replacement, if it is then ensure that it is sealed type.

Hi
So where does the hydrogen go in a sealed battery......?

 

[Dec]

If the battery is in an enclosed area like the boot, it must be vented to the outside air, on a W202 the tube exits through a hole in the boot floor.

As far as I know a sealed battery has vent holes too, the may be hidden by blanking covers.

Dec

 

[Kaiman]

I've dried out the compartment and put the tube in place. I also found the bracket/wedge to hold the battery in place, it was in the boot!

Now to sort out the problem with the electric windows. Anyone know where the relay unit is situated? I'll star a new thread soon.

 

[mattkh]

Now to sort out the problem with the electric windows.

Hi
What is the fault ?