Jensen Monday Club

Fuel Tank Strap Replacement
 

On the way up to Scotland last year one of my fuel tank straps broke; it had rusted through and just fell apart. There are four straps, two per side, that hold the fuel tank in place. You can see the left hand side pair in the picture below. I decided to replace all four anyway as the others were looking just as rusty as the one that broke.

For better access put the rear of the car on axle stands and remove the rear wheels. Put the stands under the chassis tubes not under the axle; this lets the rear axle hang down under its own weight and gives more room. Remove the spare wheel and also the wheel carrier (2 bolts at the hinge side and completely unwind the height adjuster until it undoes).

Each tank strap has a fixed bolt at one end (top-front) and a sleeve spacer at the other end (rear-bottom). You can also just see that there's a strip of rubber between each strap and the tank.

It is possible to replace the straps whilst the fuel tank is in the car, but only if you're able to undo the nuts shown in the picture below. This is because the bolt that comes down from the "U" shaped bracket can only be removed once the tank has been dropped. If the nuts on these bolts undo ok then you can replace each strap in turn without removing the bolt whilst the other straps still hold the tank in place.

 

Pic 1

You can see below a picture of the top-front bolts, these are the ones that are fixed to the front end of the straps. They poke up through the boot floor and emerge under the thin metal flap that covers the fuel tank vent pipes. You can still replace these even if you have to cut the old ones off because the new bolts are part of the new strap. There will probably be a little settlement as the new straps adjust to the shape of the tank under heat/load so best to give these nuts a tweak up after a couple of weeks

Pic 2

That's all folks; but if like me you want to take the tank out whilst you're there anyway to give it a clean, flush and re-paint then read on:

 

Fuel Tank Removal/Re-fit
 

First job is to disconnect the battery, always wise when working with petrol in a confined space... Then you need to get the fuel out of the tank. You have two choices, you can undo the drain plug, but if you do then you'll need something low enough to go under the rear of the car but big enough for the amount of fuel. If the tank is almost empty then this approach works well and any old fuel can be disposed off. We chose instead to siphon the fuel into a jerry can and put it into one of the other cars because my tank was about half full (bad planning, I know, I know !).

Pic 3

Next: you'll need to remove at least the rear end of the exhaust on either side. How you do this depends on the state of you exhaust. You only need to remove the rear pipe with resonator. But if like mine your exhaust has been on the car for several years then you may not be able to detach the exhaust where the rear pipe attaches to the rear of the box. If this is the case then it's easier to just remove the whole system. To do this you'll need to undo:

  1. The front end of the rear silencer box hanger assembly. To access this lift the rear seat cushion and you'll find a big plastic blanking grommet. Prize this out and you can then get a socket onto the bolt that holds the front end of the assembly.
  2. Undo the bolt that holds the rear end of the rear silencer box hanger assembly. This is easy to get to because it is just above the rear axle in the void between the fuel tank and the floor/seat back.
  3. The front joint to the exhaust manifold (for which you'll probably then need new gaskets).
  4. You can now lower the front of the assembly to the floor with the rear end still attached by the hanger straps.
  5. Undo the rear hanger straps right up behind the resonators. This is usually easiest to do where they attach to the exhaust pipe (a standard "U" bolt etc.) rather than up at the floor end where there's a "cotton real" type fixing that will probably break before you get the rusted nut undone.
  6. Having undone this last fixing the whole exhaust can be lowered to the floor and slid out from underneath.

Next: undo the fuel filler hose, there will be a jubilee clip (or similar) holding this - one at the fuel filler bowl end and one direct onto the neck of the tank. We couldn't get the tank-end one off in-situ so just undid the bowl end clip. It is possible to remove the tank only having removed the clip from one end but its easier if you can get both off. This is an ideal time to replace the filler hose anyway as they do tend to collapse internally even if they look ok from the outside. If you're having trouble filling the tank at the pumps then this could be the cause. To get to the filler hose you need to remove a small splash panel in the rear wheel arch which is held in place with two self-tapping bolts.

Then: undo all the tank strap bolts. The top ones may need a bit of gentle persuasion once undone before they'll let go - see below:

Pic 4

If you're replacing the straps anyway and can't undo the bolts (at either end) you can just cut through the straps and/or bolts and bend them out of the way. Put something under the tank so that it doesn't fall when you remove the last strap. The tank isn't very heavy (when empty !) so just a footstool or similar will do.

The tank can then be lowered down and slid out from under the car, see below, this is where you'll need two people.

Pic 5

After that, the tank was flushed through with the drain plug removed to get rid of any big bits of debris and given a coat of paint. The replacement is the reversal (hah!) of the removal. You definitely need at least two people, three is ideal. Here's what you need to do:

  1. Use some household glue to stick the rubber strips to the tank-side of the straps - this just holds them in place whilst the tank/straps are manoeuvred into position, so they don't need to be really well stuck down, just anything temporary will do.
  2. Attach the new filler hose to the tank end but don't fully tighten the jubilee clip.
  3. Hold the tank up in position, having previously inserted the rear bolts into their "U" hanger brackets whilst you still have access. You'll have to move it around to get the filler hose to align with the filler bowl but this isn't difficult as you can wiggle the tank about to get the right angle.
  4. Push the spacer rear-end of all four straps onto these now captive "U" bracket bolts and put a nut on with just a couple of thread turns - this leaves the straps attached but as loose as possible.
  5. This is where the third person comes in handy. One person holds the tank, the second person pushes the fixed-bolt end of the strap up through the boot floor and the third person puts a nut on the thread inside the boot. Again, leave the nuts loose until all four are in place.

Now you just need to tighten everything up and the straps will pull themselves into the shape of the tank - don't try and bend them into shape beforehand as they will never be exactly the right profile for the tank. There's enough movement to get the straps into roughly the right position and then just let the bolts do the work.

Just a final reminder to check the tightness of the fuel tank strap bolts after you've done a few miles and everything has settled.

We have had a contribution from Patrick in Canada with some tips on fitting the straps on his MK2.

 

Refitting MKII Interceptor Fuel Tank support straps

I followed the Monday Club instructions to remove and replace the fuel tank on my Mk II Interceptor. I took the tank off, sent it out to be cleaned and epoxy coated. I found the source of the annoying intermittent smell of fuel was a combination of missing vent hoses and a leak in the fuel connection between the tank and the fuel line. I also checked the fuel level sender rheostat to confirm that the level sender and low fuel light switch were functioning. I replaced the float [A standard item used in MG-Bs and TR6s, available from Moss motors] which was half full of fuel. At this point I was a happy camper!

Things continued to go well as I replaced the tank, until I tried to replace the right hand tank straps. I had the tank nicely located, supported on a jack with the base of the tank protected by a piece of wood. The left hand straps went into place easily, but I had problems with the right hand straps.  I could not thread the front bolt through the narrow gap between the Panhard rod and the front face of the tank and could see no way of fitting the forward bolts through the boot floor. I contemplated dropping the Panhard  rod, but this seemed to be  a complication I didnt need .

After a lot of head scratching I found the answer. If the bolt and strap are in a perfect straight line you can thread the bolt between the Panhard  rod  and the tank at the centre of the car where there is greater clearance . Its then fairly easy to slide the strap sideways until you can push the bolt up through the boot floor. You obviously have to fit the outboard strap, the one nearest the wheel, first .

If You Can't Undo the Nuts Addendum

136-8779 also suffered from a broken fuel tank strap, so I decided to replace all 4 as Chris described above.

The issue I had with my car is the the nuts in Pic1 were utterly corroded and seized. I had sprayed them for 2 days before hand repeatedly with penetrating oil, but they would not budge. In the end I had to use a nut splitter to get them off.

Even after 2 days of penetrating oil, the threads were still bone dry

This then leaves you with 2 options:

1. Use a "Thread Chaser" to try and recover the threads on the original bolts.

2. Drop the tank slightly and remove the bolts. It is not possible to remove the bolts with the tank in situ.

My plan was to try and drop the tank the minimum I could to get the bolts out, then replace them with new stainless steel ones. If the tank failed to budge, and it looked like it would be damaged trying to shift it, I would borrow Steve Payne's set and try and recover the threads.

As the centre of the tank was supported on a trolley jack with a wide piece of wood to spread the load, and 2 axle stands at either end as a belt and braces measure, I gently lowered the tank.

It came free under its own weight, so the 2nd option of new stainless bolts was available. The bolts are 3-1/4 inch long by 3/8 inch diameter. If you can only get metric bolts, 10mm is the nearest equivalent, but is a very tight fit, and the tubes the bolts go though might need drilling out.

While the spare wheel carrier is out, it's a good time to check for corrosion and redo any under sealing as necessary, and refurbish the carrier if required

Using the original straps as the template, I bent the new ones to shape

Then glued the new rubber strips in place holding them with clamps until the glue was dry

I replaced all the bolts, including the spare wheel carrier, with stainless steel ones

When refitting the bolts to the new straps, I fitted them "upside down" compared to the originals. This will mean if the straps need replacing in the future, then the tank won't need to be lowered to remove the bolts. You will need to make sure that the bolts you use are no longer than 3-1/2 inches, and preferably 3-1/4 like the originals

Everything was then plastered with underseal as I don't want to be doing this again any time soon!