Fuel tank leak.

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Gazzaman22
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Fuel tank leak.

Post by Gazzaman22 »

C5 II 5 DOOR SALOON 1.6 HDi 110 particle emission filter (DV6TED4) Manual gearbox 5
Seem to have a small leak some where in tank. It's not coming from the filler pipe as there is no spillage coming from it.
Haven't got it up on the ramp yet, but has anyone a diagram of the removal of of the tank.
It's a tiny drip seemingly coming from maybe the top side of the tank.
Is there any pipes that could let a leak out if it on the upper side? Put approx 50 liters in it the other day. Wonder is there a small crack in it.
Gary

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Paul-R
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Re: Fuel tank leak.

Post by Paul-R »

If you lift up the rear seat base you will see a large round plastic plug. This covers over where the tank sender unit sits in the tank. It also has the output and return fuel hoses. You might see something there perhaps?

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Re: Fuel tank leak.

Post by Steve Walsh »

About 11 years ago I had a 406 estate, I ran over a piece of metal, I saw it at the last second and couldn't avoid it, The wheel flipped it up and it punctured my diesel tank on the bottom, I parked it with a container underneath until it stopped dripping, then cleaned around the hole with aerosol solvent and through the hole. Then repaired it with a hot melt glue gun. It was still leak free when I sold it 9 years later..

Gibbo2286
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Re: Fuel tank leak.

Post by Gibbo2286 »

A common place for leaks on these is where the pipes from the tank curl around the corner at the back (behind) the right hand sill.

Gazzaman22
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Re: Fuel tank leak.

Post by Gazzaman22 »

Paul-R wrote:
21 Apr 2020, 16:42
If you lift up the rear seat base you will see a large round plastic plug. This covers over where the tank sender unit sits in the tank. It also has the output and return fuel hoses. You might see something there perhaps?
This is weird. So found that unit, and there was deisel all over it so dried it up and checked in and out hoses. Also wrapped kitchen roll around each connection to find out which was leaking. Cam back to it there this afternoon 24 hours later and the yellow cap is all covered in deisel again. Like puddles of deisel. None of the pipes seem to be causing the leak as both were dry and no spillage on kitchen roll.

Is it possible that the black capping that holds the yellow cap is cracked and the deisel is siphoning up on the yellow cap???
20200424_173115.jpg

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Paul-R
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Re: Fuel tank leak.

Post by Paul-R »

I have no specific idea where the fuel is from but what I would do is dry the area off again and see if it becomes easier to see where the source is. Keep drying it off until (hopefully) there's no problem seeing where it comes from.

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bobins
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Re: Fuel tank leak.

Post by bobins »

I've had one of those types of connectors leak before now. I 'cured' it by tensioning it over to one side i.e. pulled it a little towards the other connector and kept it held there with string or wire.

Gazzaman22
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Re: Fuel tank leak.

Post by Gazzaman22 »

So dried it off and watched it for a while. Is coming up between the yellow(pump) aand the black cap.....slowly.

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Re: Fuel tank leak.

Post by Steve Walsh »

A while since I had one of those out, I think there is an o-ring around the pump unit, Is your tank full to the brim? If not I am guessing a crack in the pump and a replacement required

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Re: Fuel tank leak.

Post by Steve Walsh »

I use this Company for a lot of stuff, Not sure where they ship to, but they stock a lot of Valeo OE Stuff

https://www.oscaro.com
Last edited by Steve Walsh on 26 Apr 2020, 07:37, edited 1 time in total.

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Paul-R
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Re: Fuel tank leak.

Post by Paul-R »

You must have the tank pretty near full for that to happen.

You will have to take the hoses and electrical connector off the pump/sender. Then unscrew the black ring to release everything. There is a special tool to take the locking ring off but if you're very careful you can tap it off with large blunt screwdriver and a hammer. Tap little by little at various points around the ring hoping that you don't break any of the plastic.

When you take the pump/sender unit out you can then inspect everything to see why it's leaking. It's strange for it to start leaking spontaneously. Has anything been changed there or taken out for inspection? You're supposed to fit a new O-ring if anything is disturbed there. A new one may solve your problem if you're lucky.

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Re: Fuel tank leak.

Post by Gazzaman22 »

Cheers lads, yeah last time I stuck in 50 litres, but nothing else has changed, but generally I do stick in 50 every Time I top up.
I had got an injector seal replaced about a month ago.

Is the rubber O ring under the black cap or is it part of the sender unit?
Would a bead of silicone under the black cap be an idea?

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Re: Fuel tank leak.

Post by Steve Walsh »

I wouldn't use silicon, If it is the o-ring leaking, I would replace it.,, Just a thought. Is the black ring actually tight.

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Paul-R
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Re: Fuel tank leak.

Post by Paul-R »

O-ring is under the cream plate and held down by the black ring. Definitely don't use silicon sealant.

I also always fill my tank to the brim and it seems strange for it to suddenly start leaking (repeating myself there). If your filler neck doesn't incorporate an anti-syphon device then you should suck some of the fuel out otherwise you'll have to wait until you can drive the car to use some fuel up. If the clamping ring has become loose then try just tapping it round tighter but be prepared to have to unscrew everything and clean the mating surfaces.

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Re: Fuel tank leak.

Post by Gazzaman22 »

Yeah I tighted it up by tapping it as mush as I could yesterday. But it was no help and fuel was still slowly seeping out between black cap and sender.