I live in a pretty wet area (Ireland) and am looking to buy an nb1 soon enough. What are the ideal ways of checking for rust on the front chassis rails and rear sills? Also, how common is it for nbs to develop rust in wet climates?
Posted Dec 14, 2017, 10:30 AM UTC
Open the trunk and check the left part under the piece of plastic (you can easily take it out), it's possible that it's rusted through there. Also the side of the battery (less common). For the chassis rails just turn the wheel all the way around and it will make it easier to check. Try and feel the the bottom of the chassis rails, some have holes in them (if you spot this, walk away). Take your time to check it! I can't stress it enough, don't make the same mistake I made. Chassis rail repairs are quite costly.
You'll find plenty of advice for sills, so I'm going to emphasize NB frame rails: be incredibly critical. You will not see obvious outside rust developing on these until it is far, far too late. I had mine fully replaced last year, so I have a before-and-after. Turn the wheels aside and look at the exposed bolt and drain holes inside the well. If there is rust in them, walk away. If the undertray is gone, expect rust until proven otherwise. Open the hood and run your hands down every exposed surface of the frame rails. If you feel the slightest lump or deformation, RUN. That car needs expensive surgery. Shine a light through the holes in the deck above the rail and look through, especially around any nuts or holes. If you take it to a mechanic for a PPI, ask them to run an inspection camera through the front drain hole (at the bumper gusset) and look at the floor of the rail.
Unfortunately, unprotected NBs will develop rust there sooner or later. Given it's been 12 years since the last one was built, if it's driven on salted roads and not protected somehow it's almost certainly there already. To protect it chassis wax or other sacrificial coatings inside and underneath are the best approach. I assume you know about the sandwich construction already; when I had mine redone, I had the insides coated with weld-through rustproofing primers before assembly, coated the rims of the drain holes with POR-15, installed a factory undertray, and filled every unused bolt hole with a bolt to stop splash. This all may be overkill if you wash your car regularly, but I'd already done it once and I'm not interested in doing it again.
https://i.imgur.com/NyYunKV.jpg
https://i.imgur.com/07j0LwI.jpg
https://i.imgur.com/dZ9P5Mw.jpg
And inside:
Very common for them to rust. Get on your back on the ground, bring a flashlight and check everywhere you can underneath the car. Check for bubbling near the sills, that means it has rust that's ready to pop through the paint at any moment. Also check underneath the spare tyre to see if there's any rust/water/moist. Check the trunklid as well, they rust hard too. Then under the bonnet: if you see rust on any structural part of the car there, walk away. Good luck.