Treating rust under underseal

[DomP182]

Finally started the horrible task of removing the rust behind my fuel cap but I've found it tracks back under the underseal towards the rear light assembly.
I've armed myself with BH deox gel, electrox and dynax ub by my question is after deoxing would I be best to electrox then dynax for just apply dynax straight to the affected area after deox gel?

 

[d19wood]

Once gel has done it's thing make sure you clean and dry it thoroughly ( I used meths ) then zinc primer to inhibit oxidation, then coat of paint and finally wax sealant

 

[Martin.]

Finally started the horrible task of removing the rust behind my fuel cap but I've found it tracks back under the underseal towards the rear light assembly.
I've armed myself with BH deox gel, electrox and dynax ub by my question is after deoxing would I be best to electrox then dynax for just apply dynax straight to the affected area after deox gel?

Does your car have a tiny hole in the plastic on the lip beneath the fuel filler cap?

Mine does, and I'm wondering if its where the rust has started from water seaping down there...

My mates 172 cup doesn't have said hole.

 

[DomP182]

Does your car have a tiny hole in the plastic on the lip beneath the fuel filler cap?

Mine does, and I'm wondering if its where the rust has started from water seaping down there...

My mates 172 cup doesn't have said hole.

I think mine was definitely from dirt build up from behind, not a pretty sight now I've mostly cleaned it up!

Not sure what to do about the hole, get a patch welded in or a layer of filler

 

[d19wood]

Isopon P40 will span that size of hole no problem. I used a zinc mesh the Mrs had in her crafting room along with P40 but the holes were worse on mine. The zinc mesh was from hobby craft but I think aluminium mesh is more regularly used for this purpose.

 

[d19wood]

Isopon - U-Pol

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Isopon - U-Pol

The new ISOPON range has been specially developed so car enthusiasts can repair and restore their vehicles quickly and easily at home.

www.isopon.com

 

[White16valver]

Would there be galvanic corrosion between aluminium mesh and steel bodywork?

 

[d19wood]

Probably as it does with motorbikes especially with road salt but much less so with my downhill bikes with the absence of salt. I think the idea is that the mesh is sacrificial to prevent further damage to the body panels but someone will be able to say better than me.

 

[DomP182]

Would a hole the size it is even need mesh?

 

[d19wood]

Doubt it

 

[R3k1355]

Would body filler absorb water in that area and create more rust?

 

[DomP182]

Would body filler absorb water in that area and create more rust?

Once I've got it back to metal with Deox gel I was going to cover it in Electrox after filling then Dynax UB. That should be ok shouldn't it?

 

[d19wood]

Grind down with wire wheel
Degrease surface
Treat with Bilt Hamber Deox-Gel
Wrap in cling film and leave for 24hours
Clean off the Bilt Hamber Deox-Gel
Fill any holes allow to dry and sand back
Zinc primer
Paint
Finally wax coat

 

[Louis]

Put a bit if zinc down before applying filler.

 

[DomP182]

I did wonder this, as I'm going away for a week and not going to get time to finish I had thought of giving it a coat of electrox to protect it while I'm gone.