'74 412ls fuel leak

[3nero]

For the last week or so there has been a real strong stink of fuel in my 412 so strong that i now drive with the sunroof open. So today i put it up on ramps and slid under to see if i could trace it.

The rubber pipe that comes out of the fuel tank is fine but that connects to a metal pipe and then disappears inside the floor.

About 6 or 8 inches back from where the pipe enters the floor there is a small hole, and this hole is where the fuel is dripping from.

It looks like the hole used to have some kind of tape over it and there is a similar hole a few feet further back which still had the tape over it, so i pulled at the tape and fuel then started to drip from the second hole

I pulled up the carpet inside and there is no access to the area inside the ..em...tunnel.

there are pipes running either side of the tunnel but i'm not sure if they are for fuel or not.

so any Ideas what my options are here?
I was thinking of running a new pipe outside the tunnel and back to the engine, but i would rather fix it properly.

[Lahti411]

Most likely you have very rusty fresh air intake box under the das board. This leads water leaking on the front floors and inside the tunnel where the gear linkage and fuel lines are located. And this ofcourse means the fuel lines will eventually rust out.
I've replaced the fuel lines of my 411 with plastic ones. These are similar in inner diameter, and durable enough to take the pressure of a fuel injected system. Fuel injected Saabs used to have these same fuel lines.
You have to remove the old, rotten fuel lines from the back of your car. Take the gear lever out and cut the fuel lines from the openig. Then remove the foremost parts of the fuel lines from the front where they go inside the tunnel. From the gear lever opening you can see some clamps that hold the remaining fuel lines in palce inside the tunnel. You'll have to pry these open. Then go under your car and remove the gear linkage coverng boot, open the gear linkage connection to the gear box to give you better acces, and remove the centering plate from the tunnel openign. From the gear linkage opening you can wiggle the fuel lines out by hand. Then you'll just have to push the new plastic fuel lines in from the front and clamp them in place, using the old clamps.
Oh, and there shouldn't be any tape covering those openigns you were pointing out. These opening are there to let humidity out and they also work as body measuring points when extensive body repairs are needed.
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My cars: 1972 VW 411 Variant; 1973 VW 412 4d sedan

[3nero]

I haven't looked yet (afraid to) but i'm sure you are right about the fresh air box. It's always raining here and my car lives outside

In the last pic posted you can see how damp the floor is. This is probably the beginning of the end for this car.
The battery dropped today aswell

I just spent a few days fixing the clunky gears and now i have to take the stick off again

[Lahti411]

I have never seen a type 4 with solid fresh air box... There is a drain opening inside the box which always gets blocket as it's too small. Also the seam sealant inside the box cracks with age and lets the moisture spread between the body panles. Take the ventilator out from the fresh air box and clean the box thoroughly. If the rot isn't too bad you can simply dry the box and put in new sealant. It's good practice to pour a bucket full of water to the fresh air box to rinse it thoroughly. Otherwise dust, leaves etc. will collect inside the box, keeping it moist all the time.

Did you change the front bushing for the gear linkage before you started adjusting it? If it's in bad condition (and it usually is), it'll be very cahllenging to adjust the gear lever. If the bushing is good it's not that difficult at all. Partnumber for the bushing is 111 701 259A. It's very cheap and easy to find from just about any beetle parts shop.
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My cars: 1972 VW 411 Variant; 1973 VW 412 4d sedan

[raygreenwood]

Yes the "modern" plastic line is good...just not the original whitish plastic lines from the Saab...those were nylon and miserable with age. The later black ones are good. The modern lines on my Jetta are all plastic and good to 5 bars. Ray

[Lahti411]

Yeah, it's that black plastic pipe i was thinking. Didn't even know about the nylon fuel lines in Saabs. That black plastic pipe was dirt cheap -something like 2 euros a meter and it's available in good rubber and plastic product suppliers here in Finland.

I also remembered more accurate how i removed the old pipes from the back of the car: You need good pliers to turn the short pipe ends that come through the back wall of the floor. Turn the pipes back and forth so that they'll start moving. Try to get the rubber grommets out so you'll get more movemet. You need this as there is still one clamp for both pipe inside the tunnel and you need to bend the clamps even slightly open to get the pipes out. These clamps are under the rear foot well and cannot be reached without cutting the floor open, so wiggling them open is the only chance.
When putting the new fuel lines in you should attach some steel wire to the end of the pipe. Do this with some strong adhesiwe or even good tape will do. Attaching that wire will help you to guide the pipe ends through the rear wall of the floor. The wire i used was something like half a meter long. It has to be this long as you'll have to serve the wire form the gear linkage openign to those wall openings.

I hope my explanation makes any sense... It's bit tedious job but nothing impossible. And check the tunnels rust situation -you don't want to put in new plastic fuel lines and then start welding the floor...
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My cars: 1972 VW 411 Variant; 1973 VW 412 4d sedan

[raygreenwood]

The new polymer fuel lines they are using on all new VW's are excellent also. They hold 5 bars of pressure easily. Ray

[3nero]

well i finally got around to doing this pain in the neck job. I had a quick route around in the shed and found a roll of copper gas (propane) pipe left over from building my bay interior. It fitted perfectly into the holes where the old pipe came from and the rubber lines clamped onto each end no problem. Now my 412 smells like and old VW again and not fuel depot

[Lahti411]

Great to hear you got it sorted! Just make sure those copper pipes won't rub to the body as they will make the less precious steel to corrode.
Did you have the guts to check the fresh air box yet? How was it?
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My cars: 1972 VW 411 Variant; 1973 VW 412 4d sedan

[3nero]

The air box was surprisingly good, no rot just a small bit of seam rash on the lower left corner. I poured a jug of water into it and none leaked into the car. the leak must be from somewhere else. probably the door seal

[raygreenwood]

I should have posted earlier. I have found that the airbox is not actually that common of a water leakage and rust area...except in cold areas with snow. Yes if cases with lots of tree leaves it can get packed up and cause rust but mostly snow and ice keep that area wet too long.

The most common causes of water leakage that get into the tunnel area is from (a) the gaskets at the lower corners of the winshield. It is invisible to you because it drips down behind the panels near your knee on each side of the car. It then runs down underneath the farpet in the grooves next to the tar boards under the carpet. It never dries out.(b) in the same area...the small boot on the speedometer cable. Ray

[3nero]

someday next week i'm going to dry out the floor then put down some newspaper and soak the outside with a hose. that should give me an idea where the water is coming from. I'll get one more summer out of this car anyway then it's time to think about a strip and rebuild. I think the Irish summer is on a saturday this year