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Fuel expansion tank query
Posted: 02 Jul 2015, 14:20
by Hoopy_Frood
I just put the fuel tank and expansion tanks back on, but am having a small crisis in confidence.
I've connected the expansion tanks to each other via the valves on the top of the tanks. However...
In the Haynes manual, the pipes coming off the top of each expansion tank are not shown as connected to anything, but in the Bentley guide they show them connected to each other as well as T-piece going into a charcoal filter. I have the DG engine, should there be the charcoal filter somewhere in my van?
Thanks
Iain
Re: Fuel expansion tank query
Posted: 02 Jul 2015, 14:43
by bigherb
The Bentley is a yank manual, quite a few differences between European models always verify with a Haynes as well.
As in the Haynes the top expansion pipe should vent direct to atmosphere. The pipes just sit over the top of the tank with the ends pointing towards the center of the vehicle and angled slightly towards the rear of the vehicle. There should be a rubber bell end on the end of the pipes to stop them getting blocked.
Re: Fuel expansion tank query
Posted: 02 Jul 2015, 14:55
by dsmith1974
Just wondering, in the UK where it's not (usually) so warm..
Can you just connect the tank outlet pipe straight back to the tank inlet (eg bypass the expansion tank) and then remove the expansion tank(s) altogether? Would that pass an MOT?
Re: Fuel expansion tank query
Posted: 02 Jul 2015, 18:50
by T3luestar
bigherb wrote:There should be a rubber bell end
https://www.brickwerks.co.uk/index.php/ ... ce-t3.html" onclick="window.open(this.href);return false;
Re: Fuel expansion tank query
Posted: 04 Jul 2015, 09:28
by ghost123uk
18 months ago my van came back from a tortuous body tidy up and re-spray (long story). It came back after 2 years away (long story) minus quite a few odds n ends, amongst which were the expansion tanks
I did a temporary "thing" by taking the pipes from the tank and fitting a plastic "Y" piece in them, with the "Y" upside down (are you following me

). I then fed the pipe from what would normally be the lower leg of the "Y" (still with me?) high up in the arches. I secured it so it pointed backwards and fitted a cheap (£1.95) fuel filter onto the pipe
(to help stop muck and water getting in). That "temporary fix" has been like that ever since, through an mot and many miles (daily driver). No bad results to report.
Re: Fuel expansion tank query
Posted: 04 Jul 2015, 09:48
by Smcknighty
The only downside to this would be the loss of room for expansion in heat and perhaps more importantly the loss of the valves that stop the expansion tanks leaking if they are upside down
Re: Fuel expansion tank query
Posted: 04 Jul 2015, 10:10
by ghost123uk
Good point. Because I use LPG 98% of the time, I never put more than two or three gallons of petrol in my tank, so for me that ^^^ isn't an issue. I suppose if one was filling the tank, my "solution" would be less practical !
Re: Fuel expansion tank query
Posted: 04 Jul 2015, 15:07
by AdrianC
Hoopy_Frood wrote:I just put the fuel tank and expansion tanks back on, but am having a small crisis in confidence.
I've connected the expansion tanks to each other via the valves on the top of the tanks. However...
In the Haynes manual, the pipes coming off the top of each expansion tank are not shown as connected to anything, but in the Bentley guide they show them connected to each other as well as T-piece going into a charcoal filter.
In the UK/Europe, we were content for any vapour to just be lost to the atmosphere. In the US, the charcoal filter is an emissions regulation device.
Connect the two together, though, and you're defeating the expansion properties - the pressure in the tank has nowhere to go.
There's a secondary purpose of the whole setup - and that's to compensate for the U-shape of the tank when it's being filled, allowing pressure to equalise between the two upper halves, stopping one side from being full of trapped air.