removing gas system from tb42

Ok so Ive tuned my tb42 to petrol only and haven't run gas in a long time so I thought it might be time to remove the gas completely.
Would there be a shut off valve on the cylinder itself?
My plan is to disconnect battery terminals, shut off gas at the cylinder then start working my way from the carby back, removing the gas related parts.
The spot where the gas enters the carby is pretty easy as the carby has a custom intake and does not have the original set up with the air filter on top. Also, about 300mm from the carby the gas line has a shut off valve, so in theory even if the cylinder has no shut off then the whole system can be removed in one piece without leaking?
The cylinder was nearly empty last time I used it.

Any tips or tricks on safely removing this system?

Lucas mate , there's a valve on the tank. Lift the lid on the tank and there should be a shut off tap in there or an electronic solenoid.
good luck with the rip out mate

Sweet, cheers mate. I guessed there should be one there.

that shut off valve 300 from carbie is not your gas flow control valve is it?
Wont matter as as long as the tank is off its easy to strip the rest out

I'm still considering this as well, the cost of the tank inspection in March covers most of the cost of a long range petrol tank. And I don't do the km to really get the cost benefits of lpg.

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Originally Posted by Agronaught

I'm still considering this as well, the cost of the tank inspection in March covers most of the cost of a long range petrol tank. And I don't do the km to really get the cost benefits of lpg.

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yeah i only use mine for day trips or overnighters in the local area so no high km touring. I prefer the idea of running as efficiently as it can on one fuel as opposed to finding a happy medium between two fuels.
When i fitted the petrol spec plugs, pertronix coil and electric ignition and set the timing back to petrol specs i found it had a lot more power and also more economy than running petrol through the dual fuel set up.

So guys if you see a mushroom cloud coming from the south then you know i have done something wrong

ok so just to double check:

The valve on the gas tank has: F <---> O

Im guessing that "O" is off?


Attachment 52914

Looks like rust but its just three colours of mud haha

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Originally Posted by taslucas

ok so just to double check: The valve on the gas tank has: F <---> O Im guessing that "O" is off? <img src="http://www.nissanpatrol.com.au/forums/attachment.php?attachmentid=52914"/> Looks like rust but its just three colours of mud haha

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....or On.... Not very helpful, I know.... LOL

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Just turn it off like a tap.
I would think its not worth running gas at the prices they are now 65c a ltr plus
mine you gas was only 12c a ltr in 92 when I brought my dual fuel 4x4.
I cant justify putting in gas at todays prices, plus all the other problems you get from running it.
The newer sequential systems are a lot more efficient, but your are better off IMO running on fuel only.

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Originally Posted by Drewboyaus

....or On.... Not very helpful, I know.... LOL

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lol yeah its not all that specific. I reckon O means off because it was on "F" and i havent touched it since it was running on gas.

Next question: I have the gas in the line isolated between the solenoid in the engine bay and the valve at the tank. Do i just crack the nut and let the remaining gas in the line dissipate?

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Originally Posted by threedogs

Just turn it off like a tap.
I would think its not worth running gas at the prices they are now 65c a ltr plus
mine you gas was only 12c a ltr in 92 when I brought my dual fuel 4x4.
I cant justify putting in gas at todays prices, plus all the other problems you get from running it.
The newer sequential systems are a lot more efficient, but your are better off IMO running on fuel only.

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luckily, ive already come to that conclusion

completely off topic Lucas...... and yes I know its very unusual for me but what oil filter are you running in yours?

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Originally Posted by taslucas

lol yeah its not all that specific. I reckon O means off because it was on "F" and i havent touched it since it was running on gas. Next question: I have the gas in the line isolated between the solenoid in the engine bay and the valve at the tank. Do i just crack the nut and let the remaining gas in the line dissipate?

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I'm no expert on gas by any means but I would assume you'd look to bleed the remainder out from somewhere and that sounds as good as any....don't know what sort of pressure it's going to be under though.

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Originally Posted by Clunk

completely off topic Lucas...... and yes I know its very unusual for me but what oil filter are you running in yours?

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its a REPCO ROF-17 and it says "Can also use Z170".

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Originally Posted by Drewboyaus

I'm no expert on gas by any means but I would assume you'd look to bleed the remainder out from somewhere and that sounds as good as any....don't know what sort of pressure it's going to be under though.

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yeah thats what im guessing. Its isolated in the pipe and it has to come out so im just going to crack the tank end. I would think the pressure would be different depending on how much gas is in the tank as it doesnt seem to have a regulator at the tank end.

As i said earlier, watch for the sky to brighten from the south haha

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Originally Posted by taslucas

As i said earlier, watch for the sky to brighten from the south haha

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Quick hint : if looking for any gas leaks just use a match, if the match goes out you had a leak:)

Also a good way to empty the tank id imagine!

How the hell do ya get the gas filler pipe free from the vehicle? Mine is next to the petrol filler under the flap. It's a factory looking plate with twin fillers.

You might have to remove the petrol hose to give your self room at the rear of the filler. My gas filler has a flexible hose at the rear with a brass joiner to the filler bit. - 1/2 inch spanners (or around 19mm) where needed to undo.

The may be a little bit of gas in the line - but as the tank has a one way valve, you can crack it and let the little out.

Unless you have a wild open area way from all flame - I would not bother venting the tank.

Prepare for a struggle when removing the bolts that hold the gas tank in too. The front 3 are easy, the back 3 are a pain. I managed to get 2 out with a swivel socket but one was seized in and just threaded. After awkwardly trying to grind it out for days I eventually attached a snatch strap to the gas tank and got another GQ to pull it out from mine. Worked a treat.

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Originally Posted by GQ TANK

The may be a little bit of gas in the line - but as the tank has a one way valve, you can crack it and let the little out.

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Ahhh cool, so the one way valve is on the tank end?

I think ill hold off removing the filler pipe until I see a mechanic mate.

I'm guessing the mixer can be removed and the coolant hose just joined together.

Yes all that can be removed and new heater hoses installed,
remove converter and any solenoids, should be no gas if the tank is turned off
Filler pipe should come off when you drop the tank as one

Not going to worry about new hoses, just remove mixer and join hoses. They have a join closer to the thermostat so I'll connect them together there.

There was gas in the line because it is sealed between the shut off solenoid in the engine bay and the tap on the cylinder.

Also its where the filler pipe is connected to the plate under the fuel cap flap that I'm talking about. I don't want to just start undoing things because there is no tap on the tank for the filler pipe. Is there a one way valve in the tank end oronly at the filler end (where you screw the bowser nozzle on)

I pulled out the gas when I did my conversion, was pretty straight forward. Turned off the tap on the tank, cracked open the pipes, not too much gas came out, then stipped everything. With the filler I kept it all togeter as I dont think you can isolate it. Just had to remove the plate in the filler area from memory but they would all differ a bit. Ended up putting in a duel filler neck so didnt need it anyway. Mine was still half full of gas when I pulled the tank out and was bloody heavy and awkward, just take care get some good jacks or something ready.

There are actualy 2 one way valves - one at the tank (integral) and one at the external hose connection. see http://www.propane101.com/fillvalve.htm


I have removed a couple of tanks -

1. turn off the gas valve at the tank

2. Crack the hoses - should be a short hiss as the gas in the line escapes (keep your hands away from the gas as it will give you a cold burn)

3. Remove all the hoses and drop the tank

If you are converting back to petrol only - on efi vehicles check the supply line for the injectors as often they insert a relay to turn the injectors off on LPG

you will have to take everything out including the threaded filler and the gas compliance plate in the engine bay for inspection...you will have to get it certified by a gas place that there is nothing pertaining to gas installation on the car...de-commissioning I think they call it