Possible fuel leak

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937carrera
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Possible fuel leak

Post by 937carrera » 5th April 2015 - 8:50pm

Last time I moved my 412 after leaving it for few weeks there seemed to be a trail of fuel from the rear of the car. It has had a little bit of a petrol smell about it. The fuel gauge also tends to be bit lower than when I park it.

I have put it on the ramp today and couldn't see any leak, even when running, but having previously removed the two rubber bungs that fit on the underside of the channel that holds the gearbox shaft and fuel lines I noticed that they still seemed damp around the exit points.

Is there much experience of the metal petrol line within the chassis corroding, and if I needed to replace it how do you access it ?

Sorry, no pictures as yet...
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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shawn71
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Re: Possible fuel leak

Post by shawn71 » 5th April 2015 - 9:26pm

It does sound like your fuel line has sprung a leak, not good. How to access it, don't know but an easier option could be to run a replacement pipe under the car?

not much help sorry
'70VW 411LE 2 Door Saloon, '71 Beetle and '78 Late bay

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Re: Possible fuel leak

Post by Editor » 6th April 2015 - 12:16am

I've heard of fuel leaks in the tunnel on a Type 3, and the odd person has even run a replacement pipe through, and several have used external pipes along the floorpan edge, but I've no idea how you could do it on a Type 4 with its relatively flat floor. Presumably there is some sort of trunking that takes flow and return pipes outside the passenger shell?
Most modern cars run heavy plastic pipes clipped to the floor externally - I guess that's the easiest idea, but you would need to sort out fastening points, and it would lose a bit of originality.

If you're getting a noticeable drop in fuel level, there must be a pretty strong smell of fuel around it - even a cupful would stink the place out.

Jane and Bryan might have some experience of sorting this.
Dave.

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937carrera
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Re: Possible fuel leak

Post by 937carrera » 6th April 2015 - 8:11am

Looks like I need to find another odd person :)

I don't want to run external pipes so I'll take some pictures today and post them up
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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937carrera
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Re: Possible fuel leak

Post by 937carrera » 6th April 2015 - 10:10pm

Here's some photos - sorry they are not the best :(

This is the front of the tunnel - it does not look that bright and yellow in real life and it almost seems as though there is an plate covering an opening there

Image

Then a view from the right showing where the metal pipe enters the tunnel (on the right of the picture)
Image

Then the exit from the rear of the tunnel - finger pointing at the fuel pipe

Image

and then a wider view of the underbody from the rear which looks quite nice for an original 42 year old car

Image
Last edited by 937carrera on 9th February 2018 - 12:25pm, edited 2 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 6th April 2015 - 10:16pm

No leak showing today, but then again the fuel tank showed empty (engine running) which could be real or a sender gauge failure
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by Editor » 7th April 2015 - 1:44am

Can you get access to the ends of the pipe and try pressurising it with air (bike pump rather than compressor?) - maybe using an old car or bike valve in a bit of fuel hose and see if it holds pressure when one end is sealed? I assume there's only one pipe on your LS. It's worth making sure that's what is actually happening, if you plan to replace the pipe.
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937carrera
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Re: Possible fuel leak

Post by 937carrera » 7th April 2015 - 8:21am

That's an idea, and there is only one fuel pipe. I should be able to connect to the front of the car at the point where the fuel filter is and simply squeeze the flexi hose on the other end
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 6th June 2015 - 1:56pm

I returned to look at the 412 today - MOT is due in a month or so.

I clamped the fuel pipe from the tank, removed the hose to the fuel pump and seal the end with a bolt / jubilee clip.

I gave it a quick bleed of air from an air gun. It pressurised, and gave a little "pop" when I removed the nozzle, but after allowing a bit more air in petrol came out of the drain hole at the rear of the centre tunnel.

I dropped the front suspension carrier to see if the front of the tunnel was a removable plate. It looks like there is a plate but it may be welded in. Visibility into the tunnel is very difficult, even with mirrors and penlights.

I'm trying to work out the original construction technique here as there is not only the fuel line, but also the guide tubes for the handbrake cables going through the tunnel. I believe I can only get access from the gearlever hole from above.

Hoping someone can give me some further guidance ??
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 6th June 2015 - 3:08pm

Had another think and decided to remove the front carrier again, but lower it further and see what I could see after removing some sealer ....

From the left of the car

Image

From the right showing the fuel line (not leaking from this bit)

Image

and finally from the right rear, looks like I had a bit of a wobble on

Image

It seems as though the front of the tunnel is covered by a welded in plate ?
Last edited by 937carrera on 9th February 2018 - 12:24pm, edited 2 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 2nd August 2015 - 5:50pm

I have finally had the time to make some more progress today

I decided the best way was to assume the welded in plate would have to be removed, so I set about cutting the welds. On the basis that I hadn't seen anythink like this before I took some photos so everyone else can see what is involved;

From the front

Image

From the rear

Image
Last edited by 937carrera on 9th February 2018 - 12:22pm, edited 3 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 2nd August 2015 - 5:55pm

After a little more work with the cutting disc I was able to remove the front plate............

......... to find another plate behind

This is beginning to look like a russian doll :roll: and I am now convinced that there was no way i would have been able to thread a replacement pipe through without removing the plate

I assume the second hole is for the fuel return on a fuel injection engine

Image
Last edited by 937carrera on 9th February 2018 - 12:22pm, edited 3 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 2nd August 2015 - 5:58pm

After another little cut, it is now possible to see the inside of the tunnel. The other item in there is of course the gear selector shaft

Image
Last edited by 937carrera on 9th February 2018 - 12:21pm, edited 3 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 2nd August 2015 - 6:04pm

Happy that there was nothing else restraining the pipe, I then used a dremmel to cut the original pipe just ahead of a support and withdrew the rusty section


Image


I called it a day at this point, I'll leave connecting the pipe and having a go at welding up the plates for another day - any welding tips much appreciated as I'm a newbie at that game
Last edited by 937carrera on 9th February 2018 - 12:20pm, edited 2 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 8th August 2015 - 11:18pm

Today I decided to tackle the reassembly.

The first task was to weld up the inner plate at the front of the transmission tunnel. This wasn't the easiest job in the world for someone with almost no experience of MIG welding and a new gas bottle set up which I am not convinced is working correctly, so please don't be too hard on me for the quality of the work :oops:

This was taken after welding, grinding off the excess and painting with copper based weld through paint

Image
Last edited by 937carrera on 9th February 2018 - 12:20pm, edited 3 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 8th August 2015 - 11:23pm

Next it was time to insert the new metal pipe into the tunnel and connect it to the existing pipe. This photo was taken after connecting the new fuel pipe to the new kunifer pipe, but before connecting to the original pipe that runs to the back of the car

This was by far the easiest part of the job, even though I couldn't get my hand inside the tunnel. The original pipe was free to move within the routing clip, with a little bit of force.

Image
Last edited by 937carrera on 9th February 2018 - 12:20pm, edited 2 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 8th August 2015 - 11:30pm

Then it was back to the front of the car and time to refit the main cover plate to the front of the tunnel.

I had already cleaned and painted the inside of the plate with weld through primer to protect it, and provide a good electrical conduit for the welding.

Before I could do that though I needed to fill in the cuts made by the cutting disc in the chassis, especially as this is where the back of the front wishbone attaches. You can see this was done after a fashion..... weld, grind, weld, grind repeat..... I don't know if welding with the torch pointing upwards is more difficult than welding with the torch pointing down, but I suspect gravity isn't helping things

Image
Last edited by 937carrera on 9th February 2018 - 12:20pm, edited 2 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 8th August 2015 - 11:34pm

And now a tack of the plate onto the wishbone mounting plate with the fuel pipe routed up the front plate and round the wishbone plate. The socket and extension are there to keep the plate in situ using a bit of wedged compression from the detached wishbone. No tacks done yet

Image
Last edited by 937carrera on 9th February 2018 - 12:17pm, edited 3 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 8th August 2015 - 11:38pm

So after tacking the plate at the front, I then had to use a gearbox jack to force the rear of the plate to come into contact with the floor of the tunnel.

After that it was then a matter of running as much of a weld as was possible along the edges.

Satisfied that I had a strong job, if not a pretty one I then painted with etch primer and high build primer, hence the yellowness


Image
Last edited by 937carrera on 9th February 2018 - 12:19pm, edited 3 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by 937carrera » 8th August 2015 - 11:48pm

Followed by some black paint to make it a closer match to underseal. I don't understand why the bits of yellow are showing on the picture as there didn't seem to be any in real life.

After this it was just a matter of trimming the pipe to the correct length and re-attaching the pipe to the filter.

I have left the paint to dry overnight before fitting the suspension back and starting the car.

The reassembly took the best part of 8 hours today. I hope nobody else has to tackle this job, but if they do, at least you will have a little guide :)


Image
Last edited by 937carrera on 9th February 2018 - 12:18pm, edited 3 times in total.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by Editor » 9th August 2015 - 1:24am

Well done - it looks good for another 40 years!
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Re: Possible fuel leak

Post by 937carrera » 27th August 2015 - 12:34am

Just a little update;

On Monday I noticed a fuel smell again....... this time from the rear. Looks like one of the original fuel lines has given up near the t-piece where it splits off for the Eberspacher.

I need to fix this before I can use the car again :( - I'll replace as much fuel hose as I can
David
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1973 412LE 4 door Fastback / Saloon

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Re: Possible fuel leak

Post by Editor » 28th August 2015 - 12:42am

The double rubber hose with internal reinforcement is better than much of the 7mm cotton covered that's available now. The original VW hose was very long-lasting, or maybe the modern fuels are the problem.
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Re: Possible fuel leak

Post by Kharon8 » 29th August 2015 - 6:57pm

I'm afraid modern fuel with ethanol is killing the hoses.

Same thing has happened so far to two of my other VWs: Fuel hose replacement to modern materials helps.
Kharon - '61typ2, '63typ14,'65typ34 & '74 412
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937carrera
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Re: Possible fuel leak

Post by 937carrera » 29th August 2015 - 9:54pm

I have fixed the leak now.

There were two issues on the T-piece. On the carb feed the hose had split and there was no metal clip holding it in place. On the feed from the tank there was a leak through the hose at the joint.

I see this as being a combination of 40 years of rust and current fuels (ethanol is only ~ 5% by volume in the UK, I suspect it is much higher in Finland. Either way I need to buy some more hose
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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