Treating these rusty floor pans

[ashy90]

Hi there,

I’ve got an old MG ZS 180 I’m putting back on the road after 7 years.

I thought I would take a look at the front floor pans/jacking points which were looking very crusty (common rust point on these).

I’ve so far had a prod around on the drivers side and attacked it with a wire wheel expecting the worst, however the metal actually seems solid. I’ve had this platform of Honda/Rover/MG before and ended up with big holes in this area.

Just want some advice on what process I should follow. Baring in mind I don’t have a compressor, paint gun, spot blaster etc. I am a novice but I know that simply slapping on some waxoil from Halfords isnt good enough.

I am mainly unsure about at what stage I re-apply the lost seam sealant, and also which seam sealant to use?
I have previously used brushable seam sealant from a tin before and I don’t like it at all. Very messy. Should I use PU sealant such as tiger seal instead?

As for the process, this is what I am thinking…..

Treat the area with hydrate 80
Prime (epoxy prime?)
Stone chip (or under seal?)
+ seam sealant somewhere in this list

Any advice much appreciated

 

[steveo3002]

edit , looked closer and its worse than i thought

thats beyond rust converter , you could wire wheel it then deox gel repeatedly to see if it will clean up ?

 

[Rrobson]

Looking at the state of yours, and having experience of this exact issue on mine, that whole area will need replacing at some point in the not so distant future.
You can protect for now, and put off repairs for a bit but if you are planning on keeping longer term, think about preparing for a bit of work on both sides.

Good luck with the belts if you haven’t done them already…

 

[bricol]

Wire wheeling in my experience simply polishes the surface after removing the flakey stuff, fooling you into thinking it's nice - but drag something sharp over it and it will leave an orange, ie rusty, line.

Abrasive flap wheel is better.

 

[steveo3002]

yeah not wrong , i try and use a combo of poly strip, grinder disc and wire wheel in the hopes one will get what the other does , just make sure its rough before priming

 

[MetalMonkey]

Usually with sills they rot from the inside out, so by the time it gets to that state its pretty much done.
I suspect if you push on that with a screwdriver you will probably end up with a much larger job that you are anticipating…

If that is the case, long term it will likely need cutting out and replacing.

If it is solid, as a repair you can clean off as much of that rust as possible working back until you reach fairly clean unpitted steel and then treat and coat with an epoxy mastic.
Dig out the old seam sealer, the corrosion will have spread under it - chase it back until you get it stuck well to clean unpitted steel - you can leave that in place.
I wouldn't bother replacing the seam sealer, again just coat liberally with a couple of coats of epoxy mastic and some underseal over the top and cavity wax inside.

 

[ashy90]

Thanks for the replies.

I think it’s more solid than it looks, as I’ve been constantly jacking the car up on these jacking points over the last month or so. Granted I haven’t attacked it hard with a screw driver but the jacking points at least are strong enough to support the weight of the car.
I probably will get it cut out and new metal welded in at some stage in the future however, just not at the moment. Want to get it MOT’d and on the road first.

If I used epoxy mastic, would this be instead of epoxy primer? Or would I epoxy primer first and then apply epoxy mastic?

 

[ashy90]

Looking at the state of yours, and having experience of this exact issue on mine, that whole area will need replacing at some point in the not so distant future.
You can protect for now, and put off repairs for a bit but if you are planning on keeping longer term, think about preparing for a bit of work on both sides.

Good luck with the belts if you haven’t done them already…

Yeah I will get it cut and and repaired in the future if needed.

Belts are done - I’ve had the engine out, replaced the belts, clutch, and fitted a rebuilt lower ratio gearbox.
Cant wait to get it on the road!

 

[steveo3002]

epoxy mastic is just a thicker primer , either or just get plenty on

jotun is popular if you will use 4-5ltrs , hb primer for smaller cans

 

[Danez]

I'd apply the hydrate 80, seam sealer, primer and then waxoyl stuff.

I've started using bilt hambers own brush on seam sealer and found that really nice to use, not messy at all

If you can't poke a screwdriver through it then it'll be reyt for another couple years if well protected i reckon

edit: and if there's access (bunged up hole) try get some cavity wax in the inside, I use bilt hamber s50

 

[MetalMonkey]

If I used epoxy mastic, would this be instead of epoxy primer? Or would I epoxy primer first and then apply epoxy mastic?

One or other. Epoxy mastic is a very thick version of epoxy primer, best suited where you need to protect rusty pitted material, epoxy primer is much thinner and better for flatter panels. Epoxy primer is best sprayed, mastic is brush or roller - I apply it with a sponge which replicates a slight textured stone chip effect, works well for sills