Waste Water Tank leaking - help and advice please (1 Viewer)

[me you and pogo 2]

Hi,
We really need your help !

A class Dethleffs Premium Globetrotter 2002

We have got a leak on the waste water tank, when it is between 3/4 and full the waste water escapes (whilst dump shut off valve is in the closed position) The waste water doesn't escape when it is only half full.

The waste runs out of the tank somewhere, some how and travels across the floor to the wheel arches and drops on to the ground, it also drops waste water in to the spare wheel space which is directly underneath the short blue pipe (we found the leak whilst doing a pre MOT check ourselves)

Access to the tank is extremely limited, there is no inspection hatch, I can't see or find the wiring that goes to the water level meter. I can see and touch the blue exit pipe from the tank that runs to the shut off dump valve, this is dry until it reaches over 3/4 full.

The waste tank is between the two floors and it looks like can't be accessed from above or underneath. One side of the tank looks like it might be behind the wooden panel behind the tape measure but that gap measures only 8" so I can't get in to locker.

What should we do?

Many thanks in advance,

Dave

 

[two]

I'm not sure what some of your pictures are of (nor which way round they should be). Neither am I familiar with Dethleffs, but the tanks on some German vans can be dropped out of the bottom. You may need to remove insulation to do so. Plastic tanks can be welded, but you'll need to get the whole thing out first. Refer to a Dethleffs dealer, they may have first hand experience.

 

[cranky]

firstly, don't trust the gauge, it may not be showing a correct reading so your tank may be full not 3/4s. the pipe with the blue insert may be the culprit. if you can get some of those panels off, it looks like they are screwed on, it may be just a case of tightening the jubilee clips. best of luck.

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[me you and pogo 2]

thanks Rogher and Cranky for your suggestions.

I have tightened the jubilee clips, filled the waste tank and it still leaks, it looks like is coming from the base of the tank (but I can't see) and not from the blue outlet pipe.

Is it possible that the weight of the water in the full tank is causing a stress point that we can't see?

Been and had another look and;

- the tank doesn't look like it can be dropped because there is a lot of the chassis in the way and there aren't any visible screws or nuts - it looks like it was built from the inside.

- the panels that Cranky mentions to maybe access from the inside are glued, overlaid, sealed and screwed together, in fact I couldn't remove 2 or 3 of the screws and I am sure I will cause more damage trying to remove the panels, plus as I can only get one arm in and I am stretching.

I can't believe it was designed this way!

Dave

 

[SandraL]

I assume there is an inspection hatch. With tank empty can you hold camera in and take flash photos, perhaps you will then find cause of leak?
Of course fixing is another problem!

 

[peterc10]

As others have said the gauges can be innacurate especially if the sensors get covered in crud. So this could be an overflow working the way it is supposed to.

Maybe give the tank and sensors a good clean by putting suitable cleaner down the drains. There is another thread running at the moment on the different ways people do that.

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[me you and pogo 2]

thanks SA & PE for your replies;

We started over again trying to eliminate and understand the problem, so here goes .....

• We drained the waste tank off until completely empty and closed the valve.
• I then filled the waste tank in 10 litre amounts carefully via the kitchen sink and a 10 litre watering can until my wife spotted a leak.
• The leak appeared at 85 litres (its no good trusting the gauges as people have already mentioned, it showed only half full at this point for interest)
• The leak did not come from the short blue exit pipe (above photo) it remained dry.
• The water ran off to the wheel arch area but you can't see the water running or moving from the tank area and it then drips out on to the chassis as per photo, not so good quality that one!
• The tank capacity is 110-120 litres.
• There is no inspection hatch anywhere and we have looked in every cupboard under every carpet, there is no mention of an inspection facility in the manual either! We found the fresh water one though!
• We found the overflow pipes and they are bone dry.
• We are new to this, can you tell! lol!

We assume therefore the tank is split or damaged at a point over half way up the tank.

Have we have missed something?

Thank you
Dave

 

[peterc10]

Don't know your van so probably can't help much. If your tank is inside it should have some form of inspection hatch.

We finally found ours by lifting up one of the steps up to the rear beds and then unscrewing the panel at the bottom of the small storage space below. That revealed the top of the tank and a 150mm dia tank inspection hatch, which was the same type as the one on the fresh water tank.

 

[dave newell]

Good old Dethleffs, masters of ridiculous design showing no consideration for maintenance or repair.
Sorry I can't help.
D.

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[Xabia]

I have had a look at Globebus specs for 2011, couldn't find earlier ones, and all models quote a waste water tank capacity of 90 litres. If we assume that your model,year would not be any different then your measurement of 85 litres when it starts to leak is not that far far away from the maximum. There might be some crud left in the bottom of the tank to reduce the capacity as well. I certainly wouldn't rely on the gauge, they are notoriously inaccurate things. Have you thought about filling the tank with cheap cola from Aldi/Lidl, going for a run to slop it around the tank and then emptying - you might be surprised at what comes out!

 

[two]

I can’t help much more. I was tempted to suggest that it might be coming from a breather/overflow, especially if you were not level. The problem with a leak is that you only know where it’s going and not where it’s coming from, except that it will be somewhere higher up. If you become convinced that the tank is fractured, there may be ways of sealing it from the inside (it’s only waste).

At least you know that it has reasonable capacity before overflowing. Just make sure you empty before that starts to happen.

 

[daveandsan]

Having seen lots of Motorhomes leaving sites, I think leaking tanks must be a common problem.

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[me you and pogo 2]

Thanks once again folks, Xabia, Dave Newell, PE & Rogher.

After another restless night thinking and reading all the helpful suggestions, I will clean the tank out to remove any potential gunge and see if that helps the sensors/overflow pipe and it might improve the tank capacity if some gunge comes out.

The van was very level as I like it to be like that whilst testing stuff out.

As Xabia mentioned it is possible that the waste tank is smaller than we think, so I decided to try and measure the tank as best as I can and using the dims (H,L & W) the calculated the capacity is 95 litres, this might less depending on how much debris is in the tank.

It will be difficult to fix the leak from the inside without an inspection hatch though.

Many thanks again to all.

Regards
Dave

 

[two]

If you can get to the top of the tank, there may be something that can be removed so that you are able to see the level at which it starts to overflow. You mist have looked, but I'm surprised that there isn't a cover to provide access.
Is there a Deftleffs owner group you could refer to?

 

[me you and pogo 2]

Hi Rogher,
If only I could get access to the tank, there must be inspection hole!

I have contacted the owners group for help and info about 5 mins ago, hopefully they can shed some light!

Thanks again.
Dave

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[two]

Sod says:
1. There is an inspection hole - but it's covered over.
2. That's where the leak is from!

 

[me you and pogo 2]

Lol! you are probably right! I will let you know when I have solved this!

 

[jessthedog]

how about trying to use an endoscope camera? Will get into places you can't.
They are cheap on ebay. This one is 7 quid

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[me you and pogo 2]

Hi JTD,
That looks like a good idea, thanks for the tip, I am going to order one now!
Cheers
Dave

 

[me you and pogo 2]

Update

We have found the problem – the leak is coming from the seals joining the pipes to the tank.

There are four waste pipes from various sinks & shower trays that run in to the tank, each seal seems to be damaged and perished.

Access was very difficult but we managed to squeeze a camera phone and the photos revealed wet areas, discolouration and damaged seals, we disconnected one of pipes from the plumbing and slowly pulled it backwards out of the tank, then we managed to get one hand in and remove the seals by touch.

Piping is 28mm diameter I assume therefore the seals are the same size.

Whilst I look on the net to source these 28mm seals and ideas where I might try to get them from?

I have emailed Dethleffs to see if they have got any (no doubt at three times the price of others!)

Many thanks for all the help, suggestions and advice, this is a great forum.

You never know this information may help others as well.


Regards

Dave

 

[two]

Well, in a way, that's good news. Replacing seals should be easier than replacing or welding a tank. Have you tried CAK tanks for seals?

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[me you and pogo 2]

Hi Rogher,
Thanks for the CAK tanks info, I have just called them and emailed the photos etc, hopefully they can help me.
Regards
Dave

 

[me you and pogo 2]

Latest Update

After numerous phone calls to UK plumbing suppliers and visiting DIY stores buying seals that might work! plus loads of emails to dealerships I have finally solved the problem with very helpful service from Dethleffs in Germany.

I emailed a couple of photos over to them last Monday, they emailed straight back and kindly offered to send 4 replacements seals out to me free of charge!

The ones they sent are a better design as well, a one piece seal, the old ones looked like they two pieces glued together

They arrived today and I fitted them and they have passed the waste water tank test this afternoon......... put in 110 litres in, no leaks anywhere and then overflow started, so overall fantastic service from Dethleffs Germany and now we can get back on the road.

We are so relieved!

A couple of photos for interest.

Dave

 

[Rob Hammond]

That's what customer service should be like ,well done to them.

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[mitzimad]

top marks for dethlefs makes a pleasant change to most of the stories we hear