Discovery LPG tank leak problem

First of all I'd suggest that you get a specialist to look at it however...

If you choose not to then start looking between the solinoid and tank using soapy water to look for traces of bubbles. If that fails don't be shy of spashing whole bucket loads of soapy water around to try and locate any bubbles.

Ultimately its most likely to be a loose joint that needs sinching up on a compression joint however also look for anywhere the pipes may have chaffed on anything.. even cable ties which aren't my favoured securing method but often seen on bodges.

Don't rule out the possibility that the soliniod is leaking either and allowing gas in to the rest of the system.

Lee D

Thanks for the excellent advise Lee, but what I am trying to get my head around is the fact that the Disco wasn't used for 2 weeks, so the solenoids in the tanks were shut the whole time.

I can understand how the system can leak when the tank solenoids are open loosing gas somewhere further up the line, but not how they can leak when closed. I could understand if one tank was empty as one solenoid could just possibly leak slightly, but both solenoids leaking?

Has anyone dismantled a similar twin tank system and can clue me in on how the thing is connected together or has anyone had a similar problem?

Thanks all

You sure there are 2 solenoids? might there not just be one in the common line?

That is what I am hoping someone can tell me .... some idea of what is going to fall out when I start pulling this thing to bits.

The Rave CD gives me all I need to know about my Disco and RR Classic before I start a job, but these LPG systems seem to have no documentation. If it helps the evaporator looks like OMVL. It is closed loop with lambda sensors which starts on petrol and switches to LPG after a few minutes.

Thanks

On or around Sun, 13 Jul 2008 07:15:07 -0700 (PDT), macman enlightened us thusly:

You're correct about "how the tanks should operate", i.e. spring-loaded valve should be shut when not energised. However, the valve could have a fault. It'd have to be combined with a pipe leak as well though, since there are (should be) 2 more solenoid valves on the way to the engine.

You need to work out whether it's 2 tanks, or a double-tank working as one.

If the former, each tank should have its own valve, if it's properly installed. If it's 2 tanks made into a single unit with balance pipes, then it'll only have 1.

Most likely leak location is in the fill pipe(s) in the scenario you describe. If you have 2 tanks, there will be a T piece in the fill pipe to feed both. The fill pipe may or may not have a valve where it enters the tank. There should be an 80% fill valve inside the tank(s). There's also normally a valve in the filler unit mounted on the body. I have however had minor leaks from filler pipes before.

Get with some soapy water (or, better, proper gas-leak tester stuff) and look for bubbles...

You'll find there is only 1 solenoid, probably at the front of the line under the bonnet so there will be plenty of scope for leaky joins.

"Austin Shackles" wrote in message news: snipped-for-privacy@4ax.com...

And most likely based on a 4-hole with the gubbins right at the back of the rear tank, tight to the chassis crossmember!

I replaced a twin (2 tanks welded together with balance pipes) system recently for a customer, exact same issue, a weld on the balance pipes had failed and gone porous! When I looked into it, I discovered that this particular tank setup (2 welded together) is no longer made for this very reason - apparently a lot failed. If it's a welded set-up, you'll probably have to get a cradle, 2 new tanks,

2 multivalves, 1 contents sender, 8mm t-piece to split the filler feed, 6mm non-return t-piece for the feed out and some 6mm and 8mm gas pipe, and possibly a 8mm to JIC adaptor for the filler. Badger.

And looking at Badger's learned reply I'm now aware that there are significant differences between a UK LPG installation and an Antipodean one.

Great information thanks very much to all ...

Badger, was it not possible to re-weld the joint that had failed on the twin tank set-up? Also would it be easier to replace the twin tanks with a single toroidal tank bolted to the underside of the floor of the truck, assuming they have died?

MacMan

Do you really want me to answer why you shouldn't even be considering welding a rusty pressure vessel full of explosive vapours, whether under pressure or not???????? KA-BOOOOOOOOOOOOOOOOOOOOOOMMM!

Depends on vehicle. Customer wanted the same range at minimal cost - 2 40ltr tanks are considerably cheaper than a fancy filled-torroidal even after adding the multivalves into the equation. Badger.

Reduces the genepool!

Vac purge and then fill with CO2? Far less risky than welding petrol tanks. Petrol tanks the stuff hides in the seams and keeps on vapourising.

No problems welding petrol tanks, as you say but leave the pipe in the tank and continue purging slowly with the inert gas while repairing with oxy-acetylene. Even if you wasted a full bottle of gas (which you won't), it's still cheaper than a new tank. Done lots, mostly motorcycle tanks.

Martin

You then have the legal issues of pressure vessels that haven't been pressure-tested and certified. In all honesty, if it IS a weld or part of the tank that's gone porous, what condition are all the other welded seams going to be like if one has already corroded heavily....? Not worth it. Think safety, replace with new ones that give you a certified 10 year life. Badger.

Absolutely with LPG tanks, but I was replying to the comment on petrol (gasoline) tanks.

Martin