Petrol tank removal and fitting

[diff-breaker]

Has anyone got any top tips for removal and fitting of a new petrol tank?

[Litch]

Can't know if you have an 88 or 109 but essentially the procedure is the same. It is an easy enough job but make sure the old tank is completey empty before undoing all the fixings otherwise the weight can catch you unawares. Also ensure you have undone all the pipes/wires otherwise you may cause damage when you lower the tank. Use a trolly-jack to help take the weight, helps no end.
I have usually found that when the tank has been removed, inadeqate underbody cleaning by previous owners has left a layer of mud between the tank and the chassis, this area is usually rusty/rotten and needs to be at best Waxoiled and at worst welded before the new tank is fitted.

[Canada Al]

LWB , SWB , Full , or empty ??????

[ian_s]

I have usually found that when the tank has been removed, inadeqate underbody cleaning by previous owners has left a layer of mud between the tank and the chassis, this area is usually rusty/rotten and needs to be at best Waxoiled and at worst welded before the new tank is fitted.

this is exactly what i think has happened to mine, and i'll be taking my tank off sometime next week to have a look
god knows what i will find

[Litch]

Certainly this is a major problem when the tank is under the seat (SWB, LWB ex-MOD with underseat tanks) as the gap between the side of the tank and the main chassis rail is very narrow and unless you make a point of cleaning this area the mud collects causing a rot-spot. No need for pressure-washers etc, just direct the nozzle of a garden-hose into this area, if the muck is packed tight you have a problem in the making but if it is clear then you have every chance of keeping it that way and avoiding problems in the future.
The first time I did this (20-years ago when I had to replace the tank on my first S111) I was shocked with what I found and had to weld in a significant amount of metal as the main chassis-rail was completely rotten on that side (it rots the tank as well). After that experience I have always made sure this area is clean & rust-proofed, I have even gone to the extent of removing the tank on a recently bought vehicle just to check & rust-proof properly.