Mondial QV Fuel Tank

Discussion in 'Mondial' started by Axelsson, Jul 12, 2006.

  1. Axelsson

    Axelsson Rookie

    May 9, 2006
    Los Altos, CA
    Full Name:
    Anders Axelsson
    I believe there is a leak in my fuel tank or perhaps the lines/hoses. It is on the left (drivers side) and I can notice it if I would fill up the tank. Looking at how the fuel supply works I can see several areas like the fuel vapor lines or the fuel tank limiter I would like to check. The question is how do I access the fuel tank and the fuel lines/hoses.
    Mondi QV 84 Cab
  2. To remove this ad click here.

  3. miketarrant

    miketarrant Rookie

    Jan 9, 2004
    Hi Axelsson,
    I won't be much help but I have exactly the same problem. If I fill the tank right up it dumps about a litre on the ground. 3/4 full is no problem.
    I don't know where the leak is but access to the tank is near impossible. Would love to know how to remove the tank without removing the engine first.
  4. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    San Antonio
    Full Name:
    Russ Turner
    I had a similar problem. Mine was due to fraying old fuel lines. All of the Mondials are getting on a bit in years, and the fuel hoses do warrent replacement,

    There have been several recent threads on failures of and replacing the filler hose in 308s, and the Mondial is similar. In addition to the port side of the car, it worked well for me to jack up each l & R rear sides of the car, remove the wheel and inner wheel well and rnr the old fuel hoses.

    In my case: on the starboard side, there is the main fuel feed lines coming in from below and several return and evaporative lines entering the top of the starboard tank. I had several leaky and seeoing fuel.

    Good luck!
  5. Philjay50

    Philjay50 Formula Junior

    Jan 16, 2003
    Chester, England
    Full Name:
    Sorry to hear about your problem, my 84 qv smells of fuel some times. I was convinced that the problem was the tank. Get the rear of the car in the air and you will see a panel that runs across the back of the tub. It is just a cover plate for the tank, undo the 6 or so bolts and you can check out the condition of your tank, pipes etc, and put your mind at rest or not as the case may be.

    Good Luck
  6. miketarrant

    miketarrant Rookie

    Jan 9, 2004
    Have just found the leak in my Mondial tank. The right hand metal coolant pipe that runs between the two tanks has rubbed a small hole in the tank seam. I am trying epoxy tank repair but don't know if it will be sucessful. Having removed the heat shield, wheel guards and the coolant pipe, it now looks simple enough to remove the right hand tank if the epoxy fix does't work.
  7. To remove this ad click here.

  8. jwise

    jwise Formula Junior

    Apr 2, 2003
    Portland Maine
    I wouldn't fix that with epoxy- too much danger of the patch failing at the wrong time. I would remove the tank and find a gas tank specialist to weld the hole.
  9. miketarrant

    miketarrant Rookie

    Jan 9, 2004
    Well, the epoxy tank repair was a total failure. So there was no option but to drop the tank and get it welded professionally. Although not a difficult job, I though I would post the steps needed for any other Mondial owners that are tempted to do a similar tank repair.
    I only needed to remove the right tank but the principle also applies to the left tank.

    First, you need to be able to raise the car at least two feet to get enough clearance for working from below. All the usual warnings about cars on jacks and use of axle stands apply. However some things are done from the top of the engine bay before raising the car. Special thanks to Scott (smg2) for the instructions on these early steps.

    1. Remove the right hand rear wheel and the inner wheel well guard. This exposes the fuel pump and water lines.
    2. Drain the fuel tank. There are various ways to do this, but I used the cars own electric fuel pump. Remove the fuel pump outlet pipe and replace with a length of ½ inch PVC pipe into a jerry can. I ran a separate wire from the fuel pump through an external switch to the battery so I could turn the fuel pump on an off without the car ignition on and without causing any sparks. Pump out all the fuel until the fuel pump just produces air.
    3. In the engine bay, remove the split pin from the throttle linkage, unscrew the locking setscrew and disconnect the throttle linkage.
    4. Undo the throttle cable mount from the rear cam cover and pull the throttle cable as far to the rear of the engine bay as possible. It will not come all the way out as the cable end fitting is too large to go through the hole in the manifold.
    5. Locate and remove the two nuts that hold the top of the tank heat shield to the engine firewall.
    6. Raise the car. From underneath, remove the large plate that covers the fuel tanks and the two bolts that hold the lower edge of the tank heat shield in place.
    7. From above, maneuver the heat shield up past the throttle cable and remove it.
    8. Also from above, with a long socket extension, undo the nuts at the top of the tank holding straps.
    9. You now need to drain the coolant. There is probably an approved way of doing this, but as you need to remove the large diameter metal coolant pipes that runs under the tank, I just undid the rubber jointer in the wheel arch and let all the coolant run into a large bucket. Note the system holds 24 litres, so you need a big bucket.
    10. Remove the large metal coolant pipes that run between the tanks by separating at the rubber connectors. Have a container ready to catch surplus coolant.
    11. Remove the fuel pipe from the fuel pump to the tank, including the metal section that is bolted to the subframe. This gives more clearance to lower the tank. Also remove the return fuel pipe to the top of the tank.
    12. Remove the tank inter-connecting rubber pipe and the short rubber interconnecting breather pipe at the top of the tank. You need a long extension 7 mm socket or long screwdriver to reach the hose clips.
    13. Pull the electrical connectors from the fuel sender unit and note the colours so you put them back on the right terminals.
    14. On my right hand drive QV, the hand brake cable crosses under the right hand tank so this must be removed also.
    15. The tank is now free but don’t be surprised if it does not fall down. It is firmly attached to the car floor by sticky rubber pads on the top of the tank. Pull the steel holding bands right down past the subframe and use a large lever (I used a wrecking bar) and a block of wood to lever on the reinforced area of the tank where the steel bands go. Eventually you will break the bond on the rubber pads and the tank will lower down.
    With the tank out I thought I would check the sender unit, as the fuel gauge was never very accurate. This comes out easily after making a special wrench from a flat steel bar and two 6mm bolts. What I discovered is that the plastic float was ¼ full of petrol so the next challenge is to find a replacement float.
  10. cianfichi

    cianfichi Rookie

    Oct 21, 2013
    Did you have to remove the starboard tank and if so how? Or just replace the lines? I only have one line going into the top of the starboard fuel tank because my Mondial is eurospec, less emissions stuff. I actually have to replace the nipple that the line gets clamped onto..
  11. mike32

    mike32 F1 Rookie

    May 13, 2016
    Can you get the tank out without removing the exhaust manifold
  12. To remove this ad click here.

  13. srephwed

    srephwed F1 Rookie
    Silver Subscribed

    Apr 29, 2012
    Full Name:
    fred brown
    I had a similar issue. My rh tank had a crack it the bend on the very top. Washed it with pine sol. had it heli arced and reinstalled. Not a big deal but I have a lift.

Share This Page