Rust proofing - where are the at-risk areas?

[vacuman]

As my ZT-T is one of the younger cars on here (registered in Feb 07) I'm thinking it could be worth rust proofing it when the warm weather returns.

Searching older threads has been helpful and I think it's something I can do with one of the many kits sold on line rather than shell out £400-600 to a professional.

So my question is this; is there a list or diagrams anywhere (I have searched without success) highlighting all the most vulnerable locations? I have read about older 75's having holes on the rear ends of the inner sills and something about corroded suspension arms.

Given that I doubt I'll do more than 3k per annum I'm keen to ensure it doesn't rot away before my eyes but also conscious of not spending a fortune that's not justified.

[T-Cut]

What I did was lay underneath and if I could see it, I sprayed it!

TC

[Rick-sta]

sills, rear suspension arms, front and rear subframes. Subframes are pretty solid on our cars but can get quite rusty on the surface, side sills and rear suspension arms are the weaker areas I'd say.

[JoeMc]

Proper rust proofing is a very time consuming, detailed and PITA job!

However; as mentioned above, get under the car and what you can see, spray it and maintain it thereafter!

To do a thorough job, it needs to be bone dry and in a bone dry environment (see first sentence)!

[vacuman]

Cheers guys.

In my experience with other brands the killer rust is the stuff you can't see, the rot that emerges from from the inside out; sills being the obvious but anything 'chassis' related typically.

What about door /tailgate bottoms and A pillars?

I presume that, unlike other manufacturers at the time our cars were built, MG Rover did not galvernise their body shells and offer 'x' year anti-corrosion warranties?

[SCP440]

Personally I have found doing this job on hot day is the best way, the products flow better and you are pretty sure the car will be as dry as it is likely to be.

I would recommend a good pressure washing off before you start, this can remove a lot of the dirt on the underside and will probably remove any loose underseal.

Don't be shy with the product you use and give it a day to dry before you start using the car if possible.

Personally I rate the Dynax range, the S50 cavity wax seems to get into all the seams and the UB dries to a resilient cote. Not cheap, 3 cans of each will set you back £100ish which should be enough to a good job but a lot cheaper than paying somebody to do it.

[johnnyb44]

There's a 75 I see at work parked up and the the rear sills look in very bad condition. They've been badly patched and painted over with black paint. The rust is bubbling back through with avengeance..The car is on a w plate. Late last year I noticed the rear sills on mine where showing slight signs of deterioration. There's no rust bubbles and they still feel strong when I push my thumb hard against them but the Zircon paint was showing signs of slight discolouration of brown along the bottom sill seam and lower flange of the wheel arch. The staining is only the size of my thumb but it's a sign of things to come for sure. I don't know whether it's internal rust working its way out or just surface rust straining. To tackle it and slow it down I've sprayed motorcycle chain grease/ oil inside the sill sections through the jacking pads and rubber bungs situated on the ends of the sill behind the plastic protectors in the wheel arches. I also wipe the sills, and arch lips over with some engine oil after I've washed the car just to add a temporary barrier from the elements. It seems to of done the trick as they now look good and appear to of stabilised. No doubt the dreaded tin worm will get the better of them at some point but every little helps to slow it down. Underneath it looks pretty good. The main underside body is spotless but I do keep a close eye on the fuel tank straps and lower suspension arms. They look a little crusty so I try and wax oil them when ever I get the chance to use the garage pit. I've seen a few shops lately selling rust stabilisers in aerosol cans as apposed to brush on. I've been tempted to give them a try but I don't know whether or not of there effectiveness.

[gazcaz]

I under seal once a year the man at the MOT loves it, keeping the rust at bay.Dont forget to do a warm jet wash after the salt on the roads has gone then do it.

[rockerbox]

Why is it sills rot on many cars, I believe ours are not too bad for it, but many are? Surely this well known issue could be resolved by manufacturers. Built in redundancy ? It's not right IMO

[Sonic ZS]

In my experience, we are very lucky with these cars. The only common rust-prone area on the body shell is the rear 12-18" of the sills, whilst the upper rear suspension arms are the main bolt-on component to watch.

The sills can be accessed via the jacking point pad holes (underneath sill), through the mounting holes for the sill tread finishers, and through various plugs & blanking squares found on the front of the inner rear wheel arches & inner sill panels. So there really is no need to drill any new holes and risk damaging the paint finish.

However, I have opened up a few sills on various cars and often find that there is a layer of mud & crud sitting in the bottom of the sill cavity. Now, this holds moisture nicely against the metal, so pumping waxoyl or similar over the top will only serve to seal in the damp and likely increase corrosion. Hence, you will either need a cheap endoscope, or have a good feel inside with your fingers BEFORE carrying out any rust proofing, and remove any mud with some shaped copper tubing & a hoover first. A heat gun to carefully dry things out after vacuuming will also be beneficial.

The rear arms are a hollow construction and again trap moisture inside. Ideally these should be removed from the car to allow complete cleaning & painting externally, before being pumped internally with rust proofing fluid.

Personally, I'm not a fan of waxoyl for internal treatment as I feel it is too thick and just bridges across spot-welded seams. I've used Dinatrol thinned about 50/50 with white spirit, which makes a real mess, but will tend to 'leach' into seams and joints overnight, providing good long term protection.