R230 Heater box drain hole location.

[Marrijon]

Hi

My 2010 SL350 has been parked outside over the Christmas period in Yorkshire's UK where it
has been tipping down for most of December. I remembered today (from previous experience) about the nightmare of water filling up in the heater box (bucket) under the passenger side bonnet vent.

It was 4 inches up from the bottom so I don’t know if it has gone down the back of the bulk head yet.

I have sponged all the water out.

There was no leaf matter or gunk in the bucket but it won't drain and I can’t find the hole to poke the wire down to clear the pipe.

Does anyone have a diagram to show the precise location of the drain hole.

Thanks v much.

 

[00slk]

On my R230's, I was unsuccessful trying to clear the drain hole from inside the bucket.
Best way is to jack the car up, place it on axle stands at the left front, remove the wheel and inner wheel arch. The rubber drain hose is located at the upper rear. It will be nlocked with moss, slim and dirt. I use a curtin wire and stick it up'um. What water is left will drain away. Some say to cut the bottom part of the rubber hose so it's alittle more open.

 

[Marrijon]

On my R230's, I was unsuccessful trying to clear the drain hole from inside the bucket.
Best way is to jack the car up, place it on axle stands at the left front, remove the wheel and inner wheel arch. The rubber drain hose is located at the upper rear. It will be nlocked with moss, slim and dirt. I use a curtin wire and stick it up'um. What water is left will drain away. Some say to cut the bottom part of the rubber hose so it's alittle more open.

Thanks for this. Did you get to it before it corroded the connector under the passenger seat foot well and sent the electronics in to meltdown mode?

 

[Marrijon]

The chap in this video looks to me a competent and knowledgeable commentator. His view is that the wire from bucket option can work.

But not easy to see how he gets the wire in the right place.

 

[SL63 Mark]

Thanks for this. Did you get to it before it corroded the connector under the passenger seat foot well and sent the electronics in to meltdown mode?

You need to look under the passenger carpet and dry out the thick foam.

In my 2004 SL55, the was some water in the heater box, not as much as yours, and the passenger side foam underlay was soaked.

This water will corrode the SAM connectors under the carpet. My car was 8 years old when I checked, and the copper connectors were quite corroded (green). There were no electrical malfunctions as far as I am aware.

So you need to have a look under your carpet and go from there.

To do the heater box drain mod properly, you need to go in through the wheel arch, as 00SLK suggested above. It is a half an hour job, and gives some confidence that the problem has been permanently fixed, unlike poking around with a wire, which is a waste of time IMHO.

I cannot believe MB had not fixed this problem by 2010 ?

 

[s5tuart]

The actual hole is at the front of the well and nearest the wing. It's incredibly difficult to get to but I did manage to do mine. I used a bass guitar string.

 

[Marrijon]

Thanks fellas. Your help is truly valued and much appreciated.

Jon.

 

[Marrijon]

BTW. Is it complicated to get the carpets up?

 

[00slk]

Thanks for this. Did you get to it before it corroded the connector under the passenger seat foot well and sent the electronics in to meltdown mode?

Both the r230's were garage most of the time, so the water sitting in the heater intake bucket wasn't deep enough to get into the cabin. All thanks to posts on this forum which brought this issue to my attention

I've not had the carpet lifted so not sure on that one.

 

[SL63 Mark]

BTW. Is it complicated to get the carpets up?

Not complicated at all, you need to peel off the trim around the lower part of the door, and pull up the plastic trim on the inner sill.

That will allow you to feel under the carpet to assess how much water is in there. The thick foam underlay can hold a lot of water.

As yours is a late model car (2010) It may be that MB had fixed the problem by then, and your foam may be dry.

Let us know what you find.

 

[Marrijon]

The plastic silver sill cover that you step over with the Mercedes Benz logo on it flexes up at each end and has no screws in the top. Before I pull too hard and snap it, are there any permanent fixings on it or is a held in by those plastic stud type fittings?

 

[SL63 Mark]

The plastic silver sill cover that you step over with the Mercedes Benz logo on it flexes up at each end and has no screws in the top. Before I pull too hard and snap it, are there any permanent fixings on it or is a held in by those plastic stud type fittings?

Err no, don't go moving the kick plate. You could bend and destroy it.

Probably best to post a photo of your sill area and we can advise.

 

[Marrijon]

Great advice. Thanks. It looks like dry and clear weather tomorrow so I may have the opportunity to have a proper look.

I did a cursory examination earlier by pulling the carpet on the diagonally angled footwell section under the glove compartment forward and that part of the bulk head looked dry right across into the passenger door side corner.

Could‘nt quite get my hand round underneath and onto the lateral part of the floor at this stage, so still not certain about any standing water. Will be back in touch soon.

 

[Marrijon]

Morning

is it this section that should lift to peel pack the trim?

 

[Marrijon]

Or this?

 

[Marrijon]

Having pulled back the carpet there is no moisture at all on this section of the white spongy underlay. Also the polystyrene fitment is dry on both sides and so is the aluminium plate. That said the carpet will only go so far back and only the tips of my fingers can fit under to touch the floor at the margin to see whether there is any water. Can’t feel any yet.

 

[Marrijon]

I have now sorted the blockage with the coat hanger method and some hot water. It’s draining properly now.

 

[SL63 Mark]

Morning

is it this section that should lift to peel pack the trim?

No

 

[SL63 Mark]

Or this?

Yes, that is the trim strip that pulls up to allow you to lift up the carpet. Looks like you have managed to get your fingers under the carpet and it is dry, if so that is a good result. I would just say, you need to feel right under, but if the front section is dry, that is a good sign, as that is where the water flows in.

 

[Marrijon]

Its hard to get a definitive view on how much dampness there is because I can’t get my fingers far enough underneath.

I’ve also removed the trim strip from the side and the carpet is completely fixed to the floor.

It won’t move any further than it has done from the front in the photos. I tried to insert a piece of rolled up kitchen towel slotted under the carpet and it came back dry. I have also managed to touch the bottom of the tray With my finger it was not wet at the door side but damp near the centre console. However, my intuitive feeling is that the water is suspended in the sponge and so will be some water ingress.

An option is to take a risk and not remove the carpets for now as I think I may have caught it before it has reached saturation point. I will be using the car much more than of late, so will turn the passenger-side heater on and operate it in the foot well direction mode so that there will be an element of drying directed at this area, although I accept that this might not be sufficient to penetrate the carpet and get to any wet sponge.