Technical Rust

[DaveMcT]

The Panda has what I believe is a design fault in the front beams which go from body shell to front bumper and carry the engine mounts. It's a box section tube with the wider spot welded flange facing outwards behind the front suspension struts wheels. This is a horrible dirt trap that easily fills with mud. The damp just sits there giving the (not inconsiderable) rust proofing a hard time. Fiat could so easily have set those beams to face outwards and avoided the problem. But I guess nobody noticed before it was too late to change the design.

My Multijet diesel has the engine out so I've been looking for signs of trouble while I have good access. The worn out front struts are also removed. I was "worried to find rust staining in that awkward access area of the front beams.

The clean up is tedious but basically you have to spare the paint and mastic sealant back to the metal and chip off any rusty scale. Mine was an issue at the furthest side where the metal creates a trough for damp etc to soak into the joints. I found the best way was a large sharp screwdriver to scrape away the paint then a slammer one to chip away any rusty scale. It has to go back to clean metal. A vibration multitool was great for getting into the corners and a small screw driver for digging out the channel. The ends are slathered in sealant mastic. It has to come off as there will be the beginnings of rust underneath.

I got mine fully clean I mean really fussy using a good flashlight and mirror with shop vac to suck away debris. I used Hammerite rust inverter but any similar product will do. Its then had a coat of primer and two coats of paint. I used Hammerite smooth but any relatively slow drying paint will do. It will get mastic over the back end to fill in the drain holes. These run into the sills and I feel add to potential issues under there. The front should of-course remain open s that water cannot collect. A wax finish over the top will keep it nice.

If you spot trouble, the struts are easy enough to temporarily remove/replace so you can work on the problem over a few days. If in doubt dig it out. If its good, repaint and mastic the area. If you find any rust stains, clean out the whole lot and do it properly.

 

[DaveMcT]

This is how the drivers side looked after the paint was scraped off but rust had not been cleaned away or treated. The camera exaggerates the horror though to be fair, I had a shock as there was no bubbling under the paint. It cleaned up nicely and I was totally anal about getting even scrap of crud scraped off and treated.

It had two coats of rust converter with a good scraping between coats.

 

[DaveMcT]

This is passenger side after a coat of primer. It was fully scraped out and treated twice with rust converter. The hardest part is the back of the upstand/flange. You have to use a mirror and get inventive with scrapers.

Round hole is the brake pipe. oval holes are filled with grommets. Darker grey area is shadow caused by the camera flash.

 

[DaveMcT]

This is looking down from the strut top mounting the showing drainage gaps. The back end (left) was full of mastic with front only open for drainage. I will be mastic filling the back end "drain holes" after painting.

Funny circle thingy is the brake pipe bracket. I'm fitting new pipes while I have easy access. They are both ok but its and easy job with engine out.

 

[DaveMcT]

This is the channel with inner wing panel at top of picture. The groove is where the box section is spot welded to the inner wing. If the box had been made with the flanges inboard there would be no dirt trap. And the fold would run water out instead of into the spot-welded joint.

The lump and nut are the ABS block mountings. The nut's zinc plating has long gone but a coat copper grease keeps things nice.

 

[Yolanda]

I had a look at that area on mine last summer, there was a build up of road dirt but when cleaned away and purged with compressed air it was fine. So I gave it a good brushing with old engine oil. I will check again when the anual service is carried out and maybe do the same procedure.
The early mk 3 is an old car now and I suppose it depends on how it's been serviced and where it's lived eg inland or near the coast.

 

[The Panda Nut]

The Panda has what I believe is a design fault in the front beams which go from body shell to front bumper and carry the engine mounts. It's a box section tube with the wider spot welded flange facing outwards behind the front suspension struts wheels. This is a horrible dirt trap that easily fills with mud. The damp just sits there giving the (not inconsiderable) rust proofing a hard time. Fiat could so easily have set those beams to face outwards and avoided the problem. But I guess nobody noticed before it was too late to change the design.

My Multijet diesel has the engine out so I've been looking for signs of trouble while I have good access. The worn out front struts are also removed. I was "worried to find rust staining in that awkward access area of the front beams.

The clean up is tedious but basically you have to spare the paint and mastic sealant back to the metal and chip off any rusty scale. Mine was an issue at the furthest side where the metal creates a trough for damp etc to soak into the joints. I found the best way was a large sharp screwdriver to scrape away the paint then a slammer one to chip away any rusty scale. It has to go back to clean metal. A vibration multitool was great for getting into the corners and a small screw driver for digging out the channel. The ends are slathered in sealant mastic. It has to come off as there will be the beginnings of rust underneath.

I got mine fully clean I mean really fussy using a good flashlight and mirror with shop vac to suck away debris. I used Hammerite rust inverter but any similar product will do. Its then had a coat of primer and two coats of paint. I used Hammerite smooth but any relatively slow drying paint will do. It will get mastic over the back end to fill in the drain holes. These run into the sills and I feel add to potential issues under there. The front should of-course remain open s that water cannot collect. A wax finish over the top will keep it nice.

If you spot trouble, the struts are easy enough to temporarily remove/replace so you can work on the problem over a few days. If in doubt dig it out. If its good, repaint and mastic the area. If you find any rust stains, clean out the whole lot and do it properly.

Really helpful as I have this issue with our Panda 169 and was thinking of doing as suggested. You have convinced me to do this as soon as possible. Thanks.

 

[DaveMcT]

It’s a real faff to do it properly but a screwdriver blade scraper and multitool gets to it. A narrow blade is best. Any rust scale is shifted by chipping it off using the screwdriver like a chisel. I went to a lot of trouble to get every scrap.
Treat with a rust converter then chip off any bits you missed and give another cost.
I primed with a good primer and painted with silver Hammerite. Then a cost of black so that any missed spots are easy to see. A second coat of black catches anything missed last time. I used a small soft artist brush with a mirror to be sure it’s 100% covered.
The back end gaps should be filled with mastic. The front stays open for drainage. A final spray of water repellent wax should seal it totally.

 

[DaveMcT]

To add - I will be running a bead of car body PU sealant along that spot welded joint at the "back" and filling the rear drain holes with the same stuff. I really don't want salt water running into the sills. I might pour 1/2 litre of ACF-50 down the rear grommet hole with drip trays under the sills to collect the excess. It's gunner be messy so still thinking about the viability as ACF isn't cheap and I don't want an oil soaked driveway. But that method should get to the areas water gets to. ACF drives water away like WD-40, but leaves a protection film that keeps water out.