Hi everyone,
I was doing a bit of investigation under the car (Punto Mk2, 1.2 8V, 2000AD) today to see what corrosion scenario was. Had gotten a look under it while it was on lift when getting exhaust replaced, and they mechs had said it looked ok, but I wasn't 100% happy.

Anyway... gory details, and I'd appreciate some tips on how to proceed.

Worst spot is on rear, driver's side (near fuel tank).


The pics here include shots before and after I brushed away lose bits of rust. There is a hole.

Other rear side not so bad I think, but could do with a bit of cleanup


Middle and especially front ends of sills a bit ratty where somebody jacked them with wrong jack (or put stands straight on them) (either way, not me):


Had originally thought of doing a bit of a wire-brush (got attachment for drill) and paint job on the sills. Is that still feasible on middle/front?

Now looks a bit more than that needed on rear?

What would you recommend in your collective wisdom? If I went to garage, what would I ask him to do and what kind of costs?

the second pic, how big is that hole?

also one pic before last that is probably rusted through the inside

thats some real rust, and i thought my car was bad lolloo

second last pic, looks like hole too.


I think you're in for a bit of weeping when you start to do clean up.

Wire brush on angle grinder is better than drill for this, drill is not aggressive enough.


First points of call:


1. Get a screwdriver.
2. Poke all the way along the sills.
3. Poke front and rear floor pans.
4. Check rear seat belt anchor points.
5. Check rear wheel arches


I think you're going to be in for some welding. You can do the clean up yourself, and any interior strip out. Then it's cut out, and weld in repair plates, seam seal, and paint/protect.


Establish the extent first.

I'd start with giving it a clean..jet wash the underside..
Wire brush all the flakey stuff off..goggles needed here.

Then waxy-oyl it
For the sill areas ideally you want something thick.. Schultz stone guard or the likes
I'd have someone tidy it up with a welder..but I've seen some get away with jb-weld on split seams..

Tyre fitter monkeys have more than likely done the damage there..

I'd have a look inside car too...these old punto's rust inside out..

flisko said:

the second pic, how big is that hole?

also one pic before last that is probably rusted through the inside

thats some real rust, and i thought my car was bad lolloo

Click to expand...

The hole is about 1.5 inches long

how do i investigate rust inside? (what you said in relation to pic before last)?

You can lift the carpets if you care that much. I'd still do the screwdriver stuff first, you don't even have to clean up before doing it. You'll quickly (5-10mins) have a feel for how bad things are....

Can I do some waxoyl with brush?

Aerosol form is easiest..
Waxy-oyl might be a bit thin for what you really need there..

Plenty of stuff out there that's thicker..

You couid go for the cheaper option-underseal..brush it on job done but its messy to work
With..don't get it on the brake pipes Mr m.o.t tester won't be pleased.

why would people even lift up cars there, thats the only reason it rusted that badly for sure lol

Lazyness..and rushing to get jobs done..

They don't care if they crush the sills..

there are 2 screws holding rear seat, nut that holds seatbelt and plastic, remove all of that and you can pull up some of the carpet to see more

Its the rear 'inner arches and the floor near the inner sills you need to check

No need to take carpet fully up..
Just remove side trim..

Have a look up in wheel arch where fuel tank pipe work is..they rot for fun there.

Underseal with added waxoyl from halfords is actually pretty good. I'd take it over the previous stuff I bought (dinitrol) and much cheaper too. But you'll get as many opinions as people....

oldhammer said:

With..don't get it on the brake pipes Mr m.o.t tester won't be pleased.

Click to expand...

I've never had an issue with that....pipes are brushed, painted and in parts covered with sealer

OK, thanks for all the help so far.

I bought a tin of waxoyl already, may not be quite the right stuff since don't have sprayer, but should be of some use I hope (got 5l for EUR19, he took EUR3 off because I pointed out there was a ding in the can).

Did a bit of poking and scraping with a screwdriver. Also a bit of looking in wheel arch on fuel tank side. It really seems to be from outside in rather than the inside out story. Damage to the rubbery underseal coating leading to what looks like classic crevice corrosion. The second to last pic isn't actually a hole, though it is a spot where the metal is thinned out quite a bit, but there's still (as far as i can tell this evening) some real metal behind it. Passenger side is overall very good by comparison.

So my plan tomorrow is

• Get wire-brush & drill to do a bit of rust removal and polishing (also have a 3M tool for this)
• Do best I can painting on Waxoyl to cover up the bits of metal I expose and to address damage to the underseal

Will probably need to get it to a garage in next while to look at some welding on rear driver's side. Any way to estimate how much that should cost?

really depends on the size...for a smallish hole like you're talking about, equivalent of 1 hours work rate or so. Charge out here is about £60 per hour. Don't expect any really neat welding, unless you take it to someone that does it for a living.


Peel off any slightly bad looking bits. Looks out for bubbles too, they'll be full of water. The rubber stuff is great. Until it gets water behind it...

clean it as much as you can that will bring costs down for sure

atom0007 said:

really depends on the size...for a smallish hole like you're talking about, equivalent of 1 hours work rate or so.

Click to expand...

"smallish", I'm going to take some encouragement from that word!

atom0007 said:

really depends on the size...for a smallish hole like you're talking about, equivalent of 1 hours work rate or so. Charge out here is about £60 per hour. Don't expect any really neat welding, unless you take it to someone that does it for a living.


Peel off any slightly bad looking bits. Looks out for bubbles too, they'll be full of water. The rubber stuff is great. Until it gets water behind it...

Click to expand...

Didn't get to it today, but did get to Halfords and picked up underseal with added waxoyl, perhaps a better option for sills than just waxoyl.

I'll have chance on Tuesday to look at this again. Before I do, a question: will I create problems for welding if I apply waxoyl/oil/underseal? (thinking of flammability)

I'd not put it on before welding.

As things go, I really don't rate waxoyl. Much better stuff out there, but tends to be more expensive.