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MG MGB Technical - New fuel tank

I am about to put a new fuel tank on my MGB,does anyone have any advice on how to go about it.I know this sounds an easy task but I can assure you that it won't be for me.
J E Turner

I had to do this on my GT when I first got it. A good trolley jack is needed. Get as much fuel out of it as you can first. Put jack underneath with a rubber pad or similar to spread the load. Disconnect the fuel sender wire, fuel filler tube and outlet pipe to the pump.Undo the bolts from inside the boot - you will probably need lots of easing oil first - leave to soak overnight. When all bolts are undone the tank can be lowered on the jack . Before replacing the new tank - paint the top with several coats of chassis paint and then spray it with waxoyl or similar - unless you have got a stainless one. The new tank can then be jacked into place but be careful not to push too hard or you will dent the tank - hence thick padding to spread the load. Good luck - Cam
Cam Cunningham

Before removing the tank make sure you can remove the rear most bolts first.
If my memory serves me they have captive nuts and there is very little room between the rear of the tank and the valence panel to hold the nuts if they spin!!!!
As Cam said, spray WD40 on the nuts and let them soak.
Regards
Dave
D M Tetlow

Guys STOP!

Before you do anything - DISCONNECT THE BATTERY.

My other advice to you, is to get a can of Petrol Tank Sealant from Frost and seal the inside of the tank. This stuff coats the inside of the tank and stops condensation forming on the inside top of the tank and prevents rust starting from the inside.

Robert
R Lynex

If putting sealant inside make sure you blow through the outlet pipe several times as it is curing as it can block the strainer. But personally I think it is waste of time, they seem to rust from the outside, not the inside especally the lower half, unless you fully protect the outside as well and expect something more than 30 years from it.

When transferring the sender make sure you put the (new) sealing ring 'tween tank and sender and not sender and locking ring. If yours is heavily corroded you may need a new locking ring as well. Ordinarily with no petrol leaks it is quite safe to tap the lugs on the locking ring (NOT the tapered flanges on the tank that the locking ring wedges under) with a hammer and drift but with petrol fumes you would be well advised to do this with non-ferrous tools. Unless replacing the sender as well of course, in which case you would also be well advised to check the gauge reading just as the fuel level drops below the pickup i.e. run out point. Replacement senders are usually way different from the originals in my experience showing 1/8 or more remaining when run out, and also only 3/4 or less when full. Probably be advised to do this check *anyway*, in case the pickup is higher.
Paul Hunt 2

as cam says
but you must waxoil the boot floor and the top of the tank even if its stainless
its the boot floor your trying to protect
boot floor big money to replace
tank not much money
Ste Brown

Had to replace my sender recently. To empty the tank, I disconnected the fuel line at the carb, and placed it in a container, ran the fuel pump until it was empty. Then jacked the car up on the sender side and everything was dry. Note: ran the tank almost empty on normal travel before I started this.
James Huggins

The tank might not be much money (to some), but changing it again isn't something you want to do before you really have to. So many tanks *do* rust out on the top because water, salt and dirt gets slung up there from the road wheels that the recommendation about waxoyling the top of the tank came from that. The tank is a lot thinner metal than the boot floor.

You can change the sender with up to 1/4 tank (or thereabouts) of fuel if you raise the rear right corner. You certainly don't need to drain the tank, and especially not using the on-board pump, that's several tens of thousands of miles of usage wasted!

Paul Hunt 2

I had a drain plug welded into the bottom of my tank. As an insurance it has been 100% never needed to use it.
Stan Best

paul
when i say cheaper than a boot floor yes its still not cheap and not easy to fit but if the floor goes the tank has to be dropped as well to repair or replace the floor so either way the tank will need refitting its just that everybody is saying waxoil the top of the tank but noone seems to worry about the floor area which will still rust if not treated at the same time as the water goes up if it cant go down
ste
Ste Brown

The Majority of MGB tanks are very easy to change. I've done it three times now. Takes about an hour. Not an unpleasant task unless you are silly enough to spill petrol everywhere.

Disconnect the sender wire.
Disconnect the fuel line and allow it to siphon into a container via a convenient bit of hose. The tank contains 40 litres when full, obviously you would aim to have a mainly emty tank, or a large container!
Undo the filler neck and if it has one, disconnect the breather hose (located next to the filler neck)
Undo the bolts inside boot, They are on the sides and rear of the tank/boot floor, none at the front.
Then crawl underneath and unbolt the four remaining nuts. two per side. The tank is very light weight and even if you were removing it a quater full, is going to weight less than 10 kg.
I find I can hold it in place with my knees easily enough and don't need any other suport.

You need to jack up (use stands) the back of the car only far enough for you to slide under to reach the 4 nuts. Or maybe park over a convenient gutter. If you have long arms you might not have to jack the car at all. It would be a bit of a sweat though.
It sometimes helps to spray the bolt threads with lubricant.
The sender may be removed/replaced from the tank with a few gentle taps with a hammer and screw driver.
You will need to pull the captive/clip on nuts from the old tank and put them on the new one.
Don't tighten any bolts/nuts until you've got them all started. When you've got the four underneath nuts on, you might need to wriggle a bit of wire in the 'bolt from the boot clip on/captive nuts' to get them lined up with their holes.
A socket wrench with a longish extension makes it all very easy. It's quite possible to do with just a spanner, but much less fun.
peter

"you might need to wriggle a bit of wire in the 'bolt from the boot clip on/captive nuts' to get them lined up with their holes"

Bolts for captive nuts *should* have pointed ends to aid location, not too difficult to grind one.
Paul Hunt 2

This thread was discussed between 15/12/2006 and 20/12/2006

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