Metal fuel tank replacement (to 85.5)

[Paul Fraser]

Just in the process of doing this so a few pointers.

1. You can repair a leaking tank supposedly, but I managed to get a whole one delivered off Ebay for £70. Thought I might as well go through the process to extend its life.
2. Fuel tank repair kit was about £50 odd from Frost and contains marine clean, rust converter, sealer and preservative.
3. I didn't do it in this order but I suggest this is what you should do:
a. drain tank; redrain a day or two later. I did this from the hose that goes to the fuel pump.
b. remove exhaust
c. remove driveshafts
d. remove differential
e. access fuel filler pipe inside vehicle (I had to take off the top of the back seat but managed to get away with not removing the rear side window. I removed most of the side panel screws and then removed the carpet, sound absorbing padding -- glued in -- and then prised off the black metal over with two claw hammers inserted at the base. You can try cutting the sealant around the edges but it's a brute force operation.
f. remove fuel filler pipe hoses after numbering both sides of split so you remember how to reassemble
g. remove fuel tank straps
h. remove fuel tank
i. take hoses off fuel tank, take off padding on corner and tabs off fuel tank
j. remove the spout at the bottom of the fuel tank, this screws out and needs to be removed to get the filter behind it out of the way otherwise it will clog up with the sealing process.
h. clean, prime and seal tank as per the Frost instructions. Underseal outside of tank when compete paying special attention to strap areas. Underseal straps.
i. replace padding and buy rubber/silicone strip to pad areas on tank and strap (obvious when tank is in front of you).
j. reassemble (the bit I still have to do!!)
some photos to follow to illustrate the above.
Will try and photo the reassembly when I do it.

 

[Paul Fraser]

Here is why you need to remove the spout off the base of the tank, there is a filter on the other side.
PS When I angleground this off I was sure the tank was bone dry and still a couple of tablespoons of petrol dribbled out. Health 'n' Safety R Us.
PPS Don't so this to the tank you are planning on putting back in the car

 

[Paul Fraser]

Here is the spout/filter removed from the collector. Note thread. I used a socket from the spout end first time, but a set of plumber's mole grips around the large rim was easier on the new tank.

 

[Paul Fraser]

The spout/filters on the two tanks were different. I don't yet know what the wiring on the newer one does.

 

[Paul Fraser]

Here is one of the fuel filler.

 

[Paul Fraser]

Here is a particularly bad undercar photo of the ledge the front of the metal fuel tank rests on. I also had a plastic tank to hand and was thinking about using that but have been told angle grinding and welding are required (Chris Horton, recent 911 & Porsche World article and an email). I think the angle grinding involves taking the top half of this beam off so that the thicker front end of the plastic tank will fit. Maybe they weld a metal plate on the top of it? It may structurally stiffen the rear of the car so I was unwilling to slash and burn. You will also have to modify the metal straps for mounting the plastic tank. Some wire splicing may be required for the fuel tank measurement sender.I may try this modification on another car once I get my own garage and pit (currently cluttering up my uncle's).