Underbody Car Help

[Mezzle992]

Hi, I’ve been searching and searching the answer to my question for weeks to no avail so I think its about time I asked.

The original underseal on my car had started to fail along with some of the factory paint causing localised rust issues.

I have removed all the underseal on my back with a blowtorch and a paint scraper and a battery drill hooked up to a car battery with wire brush attachments to clean up the rust and loose paint (best I can).the pictures I what I have been left with.

I don’t have the facility to remove all the paint, cut and weld, or clean the rust up perfectly in all areas, there are some areas of bare metal where I have been able to clean up the rust and scratched the paint. I also don’t want to use that thick underseal I’ve just removed.

My question is, what can if do? Any rust killing primer that will stick to metal and paint. Or treat the rust best I can with a wire wheel and rust gel and then prime and top cat? All this searching has confused me.
I understand the only way im I’m going to stop the rust is to get rid of it, I know that! So I want to get it to a point where I can monitor it somewhat which is why I don’t want a thick underseal coating
Thank you very much for reading 

 

[Burdekin]

To get rid of the rust: http://www.bilthamber.com/deox-gel

then

Rough sand the old paint as best you can then apply an epoxy mastic like Jotamastic 80 or 87: https://www.smlmarinepaints.co.uk/primers

You don't need to topcoat the epoxy but if you want I used this for topcoat under the car: https://www.smlmarinepaints.co.uk/topcoats/two-pack/hardtop-as contains isocyanates so if you aren't set-up to spray safely then roller and brush it on.

 

[Mezzle992]

Thanks very much that's the clearest advice I've seen so far. So just follow the directions of bit hambler and apply the epoxy. I will be topcoating, can the epoxy be brushed on? I have a compressor all set up for spraying but it's at home where my car isn't which is very frustrating although I do have a respirator for all this.

 

[Burdekin]

No worries.

The epoxy can be brushed, rollered (nicer finish than brushing) or sprayed. You should thin it more if brushing or rollering. Probably 15% to 20%, have a practice first and see how it goes.

 

[anjum]

I still have my doubts about epoxy primer over rust. Certainly wouldn't put it over some of your more rusty bits, OOh err missus!

POR-15 can be effective over light rust if the instructions are followed.
Or concentrate on getting the metal back to rust free as possible. It's hard work but worth it in the end. Deox gel works but is slow and will need several applications.

 

[Burdekin]

Definitely remove the rust before painting.

POR15 is just a single pack epoxy that will delaminate over time. Jotamastic is a 2 pack epoxy that will bond better and offer better long term protection than POR15. Personally wouldn't use POR15 on anything.

 

[johnik]

as above with por 15,i bought a chassis that had been painted with the stuff,it just laughed when i tried to remove it with a soft disc on my angry grinder but fell off in strips in other places,truley the work of the devil.

 

[Mezzle992]

I did buy some POR15 for the underside but I have decided not to use it as I contacted POR and the said they don't recommend using it over existing paint, as you can see I have a lot under there and I want some thing I can paint over the whole underside. I can get most of the rust back to bare metal, it's just the more inaccessible areas i'm going to have trouble with, but don't get me wrong i will do my very best to prep it all first (not looking for an easy way out) but my understanding on rust is if you remove oxygen and water from the mix it stops growing. This is a tricky job with limited time, tools and the car raised barely 18" above the ground.

 

[gaz_moose]

what is it? looks like a micra?

 

[Mezzle992]

what is it? looks like a micra?

How the bloody hell did you do that . Yeah it's my micra i fell a little bit in love with .

 

[pedrobedro]

If I had a pound for every Micra I've welded I'd be probably £6 richer now . I find a couple of coats of good old Zinc 182 helps to start with, slapped on liberally with an old brush that's been stood in thinners for about 2 years. Thin with cellulose thinner and put the second coat on while the first is tacky.

 

[Stag LD334]

My floor protection system from this point would be:
1 Electrox primer applied by roller, use 2 coats just to be sure.
2 Epoxy mastic, single coat applied by roller. Second coat if desired.
3 Dinitrol stone chip.
4 Colour coat.
All materials in 1 & 2 are from Bilt Hamber. I don't have any commercial attachment to them except for giving them money.
I've used this built up on my own cars and have no complaints but I'm not professional.