Hymer water tanks (1 Viewer)

Alistair33

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Aug 23, 2016
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As discussed else where, we are experiencing a leak in our new Hymer Exsis i water system.

From what I can gather from others mainly @Lenny HB the internal filler cap (blue) is below the top of the tank, see below for those not familiar with Hymer water tanks

IMG_1205.jpg


Now to me this is just plain DAFT !

After draining the tank and as much of the leaked water I could find, I traveled 20 miles, after which there was just a very very small amount of water in the garage .... so I assume this was previously leaked.

I then filled up the tank ........ at full it didn't come out if the external filler cap but started to drain from an over flow pipe under and in the middle on the van.

Looking inside, there was water coming out of the blue cap and sure enough after returning 20 miles home, there was a lot of water in the garage. So without at this point running the shower etc to see if there is are any further 'pressure' leaks, I think I've identified the problem.

So it appears that with out further action, running with full water is not an option

My dilemma & question now is should I run a beed of seal around the top of the blue cap (or indeed even around the threads ) to seal the system ? Obviously around the threads would likely to be permanent so around the top would be the best idea

What do other owners do, if indeed it is a design fault ?
 

Jenben

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Hi.

Yep, as I said on the other thread, the cap is slightly under the water level when full. However you will probably find that even if you fill to the top the overflow soon lowers the level below the cap as the water sloshes around when traveling (though not fast enough for yours by the sound of it!).

Originally ours weeped slightly, but after applying some silicon grease to the o-ring and carefully tightening then it's fine. Alternatively others have tried replacing the o-ring or even the cap itself. I wouldn't want to permanently seal it as access to clean or replace the overflow or outlet valve will be needed at some time.
 
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denisejoe

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can you get the blue cap off? If you can, check to see if it has a rubber washer underneath it I would have thought it should have some sort of seal on it. We have a rubber washer around the inside of the cap on our Euramobil. If not could you make one or buy one.

Joe

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Feb 4, 2016
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On my older Hymer it definitely has a rubber seal on the internal blue filler cap (y)
 
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Alistair33

Alistair33

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image.jpg
Is does have a rubber ring/sealwhich quite hard to the touch, and the cap was very tightly screwed down

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Jenben

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If the seal is dry it will tend to distort, particularly if overtightened. Try using plumbers silicon grease on it and you might be surprised that it seals ok. Also it will be a lot easier to loosen in future.
 

sallylillian

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I have a similar seal on the cap of my N+B tanks, and it is tightened down, when removing it does reveal a sort of flat spot demonstrating that it has met with a sealing face. Maybe chalk mark the surface it is supposed to bite against, tighten up and then remove and see where the rubber o ring has sealed and where not?

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JeanLuc

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Mine is an older model and the blue tank cap is not below top water level. However, water sloshes all around it when travelling and so far (10 years) we have not had a leak. I think the gasket on mine is neoprene rather than hard rubber. Perhaps this makes a difference?
 
Jul 29, 2013
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Had same problem on our Exsis when asking dealer they told me that if you fill till overflow runs you get this problem so now I only fill till gauge tells me 100%
Not had problem since.(y)(y)(y)
 

Lenny HB

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Perhaps mine was from the tank then as I always ran with full tanks but I also had a door seal leak.
Our first van a Hymer Tramp had the water tank under the seat and if you hadn't tightened the cap fully and filled the tank to the brim the lounge flooded. Those blue caps need to be really tight. The new van has a translucent cap looks like polypropylene same material as the tank so a bit more flexible apart from that it is similar to the blue one but tightens and undoes a lot easier. Might be worth seeing if the new style cap fits and getting one.

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Feb 16, 2013
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No help to you at all, but just curious as to why there is a cap below the water level?
 
Apr 15, 2015
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My new Carthago has two water tanks, one 120 litre tang in the floor space with a similar blue cap on it and this is fed by another 50 litre tank which is higher then the main tank. In fact it's in the wardrobe under the left hand single bed at the back.

How daft is that? Another mad German designer.

I've noticed that the blue cap on the main tank can seep a little, so I'll watch this thread with great interest for hints and tips on how to stop it.

Mike

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Lenny HB

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Oct 18, 2007
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On the coast in West Sussex
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Since 2008 & many years tugging
My new Carthago has two water tanks, one 120 litre tang in the floor space with a similar blue cap on it and this is fed by another 50 litre tank which is higher then the main tank. In fact it's in the wardrobe under the left hand single bed at the back.

How daft is that? Another mad German designer.

I've noticed that the blue cap on the main tank can seep a little, so I'll watch this thread with great interest for hints and tips on how to stop it.

Mike
I think you will find the second tank is an option they do it on some of the larger vans, standard tank 160 Lt 2nd tank increases it to 250 Lt.
 

JeanLuc

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UPDATE

I've heard back from the dealer and it is a known problem due to the seal which needs replacing from hard rubber to a softer foam construction !
Bingo!

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