WARNING: Water Tank - Risk of Falling Off

On our last European trip we were sat in line at Dover waiting to board the ferry, when someone knocked on our window. It was to kindly alert us to the fact that the fresh water tank on our Ford Transit Autosleeper Duetto was hanging off!!!
 
It seems this is not an unprecedented incident.
 
Take a look here:
 
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We were grateful that our problem was spotted before further damage – which does not really bear thinking of. (We drained the water on the spot and tied the tank with rope to board the ferry. Once in France, we made a further emergency repair with very strong wire and that allowed us to refill the tank. This lasted for the duration of our holiday – checking on each fill that the emergency repair was indeed still good).
 
The fresh water tank is held on by four “hook bolts”.
 
Their specifications are as follows:
 
M8 X 200mm
M8 X 200mm
M8 X 260mm
M8 X 120 mm
 
(It is perhaps worth noting that on the Duetto the same kind of hook bolt is also used to hold up the waste water tank). I suspect AutoSleepers have used this fastening technique more widely: so my cautionary tale may have wider relevance than just the Duetto.
 
I obtained my replacement hook bolts here:
 
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Each bolt costs less than £2.
 
I found it necessary to use a vice to slightly open up the U bends of the bolts to allow them to more easily be manoeuvred into the fixing holes in the vehicle chassis.
 
I also purchased four locking nuts from our local hardware store to substitute for the simple nuts supplied with the bolts.
 
Other than that, it was a very easy task to replace the hook bolts – and I can now sleep easily that the same problem should not occur again. (I have also covered the replacement bolts with Hammerite underbody seal with waxoyl!).
 
IF YOUR FRESH AND WASTE WATER TANKS ARE HELD UP USING SIMILAR MEANS, I DO THINK IT IS WORTH YOU CHECKING THE STATE OF THE HOOK BOLTS. IF AT ALL IN DOUBT ABOUT THEIR CONDITION: REPLACE THEM!
 
In retrospect, I do now know what contributed to the failure of one of my bolts. A few months back, I needed to drop the tank to fit a new drain tap.
 
I found that one of the nuts on one of the four hook bolts refused to turn. Turning the spanner actually twisted the bolt, so I stopped!  I was still able to drop the tank, because the other bolt of the pair did free up easily and releasing only one bolt is in fact sufficient to free each of the metal brackets holding the tank, thus allowing the tank to drop.
 
   
I did not think I had done any damage at the time, but my unsuccessful attempt to free one of the nuts must have weakened the bolt itself and this is why it failed; coupled, of course, with the general corrosion.

hello you are right i change the hooks on my duetto because they were rusty and i changed the wood board too

I recently had to remove the fresh tank on our Trident. I was shocked to see that one of the hook bolts had split the steel of the hole it was hooked into. It was about to pull through!

I made a small reinforcing plate and welded it on - should be fine now.

I would never have spotted it if I had not removed the water tank!

Steve

Well worth knowing for any model. Something else to add to my crawl underneath check list 

scrumpyjack14 wrote:I was shocked to see that one of the hook bolts had split the steel of the hole it was hooked into. It was about to pull through!

Yes, I should probably have stressed this, too. The two outer mounts (front into the sill, and rear into a cross member/outrigger) look particularly vulnerable as the metal is on the thin side.

The failure reported on the Ford Transit Forum, referenced in my first post, was due to the fact that one of the hooks had torn through the bodywork it was attached to.

Jenvid

Many thanks for reporting this problem, our Warwick Duo uses the same method of fastening and an annual check is now on my schedule.

Many thanks for the warning! I have been aware that the hangers on my Clubman are a bit on the rusty side, and I've been putting the job off for ages. You've provided the poke I needed to get under the van and replace them with stainless steel- I'll replace the plywood board as well whilst I'm there
Thanks again!
Rich

Thanks for the kind comments. I am glad the thread has been of interest and could perhaps save an accident.

Just out of interest, a couple of you have mentioned the plywood base and I have seen reference to it elsewhere.

The tank on my duetto does not have a plywood base. It is just supported by two metal brackets held up by the four hook bolts. Should it really have some plywood supporting it, or was the plywood fitted on some models and not others?

I do notice that my tank appears to sag slightly towards the centre. Would it be a good idea to fit some ply? What thickness of ply did Autosleeper use? 

The ply on my van is about 1cm thick, and is delaminating quite badly. I plan on replacing it with either stainless or aluminium 3mm chequerplate, which is readily available on a certain well-known auction site. When the tank is full of water, it will be very heavy (obviously...) I'm not surprised that an unsupported one is sagging.

Rich

The advantage of a wood base is that it should be cheap and fairly light. If you go that route, ensure that you use what used to be called "WBP grade" - probably now "roofing grade" which should be pressure treated with a waterproofing agent. It will eventually delaminate, but we sprayed the one on our mid-80s van from (fairly) new with Waxoyl and it lasted for many years, with only delamination at the edges.

An alternative to any kind of ply wood would be buffalo board.

Water tank falling off???????????? How about a full LPG tank!
Fortunately I was rolling around under our (late) Timberland, as one does,  when I discovered that one of the two steel bands holding the LPG tank had parted and the second was in an advanced stage of corrosion. Disaster was only one good pothole away.
The consequences do not bear consideration.

Just out of interest, what exactly failed on the tank supporting 'J' bolts??

The reason I ask is that mine are as new & its an old (1998) van, did yours snap? corrode?
If all is nice & firm & tight, all should be well, but if something is a bit loose, then the could wear through at the point of contact.
A couple of years ago, I high-pressure sprayed a whole 5l can of waxoil to the entire underside, & BRUSHED it all around the various clevises, brackets & hangers etc.

modelman: in my case, the hookbolt fractured mid way along its length. (As explained above, retrospectively, I know the weak point must have been created/exacerbated by trying - a few months prior to the actual failure - to undo a nut that had corroded solid).

People should not overlook the weakness of the actual hookbolt mounting areas themselves: especially the hole in the cross member (rear bracket, offside) and into the sill (front bracket, offside): especially if the sills are showing any signs of age.

Like you, I am a big fan of waxoyl - I have used it on all my vehicles for years. However, I use the thick black bitumen version, applied with a brush, (the one with waxoyl added) for all outside surfaces. I use the sprayable clear version for squirting inside sills and box sections.

I should add that any rust on my duetto formed before I bought it eighteen months ago. The waxoyl treatment was my first task.

However, with just about hookbolts excepted, the under body was in great condition for a 2002 Transit: a key factor in my decision to buy. I hope I can keep it that way! 

One last point: I still have not been able to establish which models/years were fitted with the addition of wooden ply to support the tank and whether I should now add this myself as part of a belt and braces approach to peace of mind. If it is not needed, I don't really want to add extra weight.

I will try Auto-Sleepers if no-one else on the Forum gets back on this.