996 body corrosion repair

[blueovercream]

I'm flirting with the idea of 996 ownership and have found a car that ticks all the boxes except for the corrosion on the MOT history:

- Suspension component mounting areas corroded but not excessive
- Internal body structure corroded but rigidity not affected

It sounds like I should be moving swiftly on but is there any mileage in trying to repair this if the car is bought at the right price? Does anyone have any idea what a proper repair would cost? Would presumably involve taking everything out and getting the body repaired and painted.

[LennyM1984]

I wouldn't bother unless it was insanely cheap. Although they do rust at this age, extensive rust (enough for an mot man to notice) is unusual and the repair costs vs cost of a decent one, probably don't make sense

[Billy_Whizzzz]

Always surprised me that people would always say that 996/7s didn’t or wouldn’t rust. Any car if it is used in winter regularly in the UK will rust and a 911 is no different. That’s why I spent several K carrying out an underbody refurb on my 997 and protecting it with Dinitrol and would never use it in winter again.

[Deanmg]

Rust in modern cars is typically associated with previous accident damage. Personally I would always avoid any signs of rust.

[MrC986]

I have a good PH friend with a 996.2 & his MOT had an advisory for corrosion last year (the car coming up for 18 yrs old). Unless the cars are pampered/ not driven in winter or are re-rust proofed, they will start to show some light corrosion after a while. I’m told the trick is to get advisory corrosion sorted as soon as it is spotted as it’s obviously the cheapest way to do it.

OP, I’d be looking at the online MOT history to see how long it has been an advisory as it’ll at least give an indication as to the possible severity of it. We should of course remember corrosion repairs can be as simple as removing the corrosion & applying a corrosion inhibitor to stop it advancing & yet there are threads on having to rebuild the jacking points & far worse. Aerokit cars are apparently good at hiding the buildup of crud & letting it fester.

[nunpuncher]

I'd wager the first advisory is the front strut mount areas. The front inner arches and wheel wells are only coated with underseal on the lower half so the top areas are prone to rust as they just have a light dusting of top coat over primer. This can be caught and treated as it is surface rust. The front struts would need removed to do this but it's not a big job.

No idea what area they could be talking about in the second advisory. Other rust areas on these cars are:
- the jacking points probably due to a jack or lift damaging the underseal which then lets water in.
- lower pinch weld on the sill. As above, underseal damaged during jacking or the water can simply work its way behind the underseal from the jacking point. As mentioned above, aero kit cars will hide this well and I suspect there will be some nasty surprises found on those cars
- Transmission runnel and general engine bay. Not unusual to find little areas of surface rust here due to no/light underseal, and the exposure to road grime along with constant heat cycles.

All of these are surface rust (outside rusting in) areas and easily dealt with if caught and treated properly.

Rear arches can be an issue. The area is double skinned with the backs of the panels only being primed. The panels are spot welded along the lower edge which allows a certain amount of flex meaning they can rub together very slightly. Condensation runs down between the 2 panels causing rust from the inside out. This could be costly to repair properly.

I'd want to see the car to inspect the severity of the rust as some MOT men can be a bit over zealous with their judgement on these things. It's not like a brake pad where there's a measurable point where it needs advised or failed.

The comment above about rust on modern cars indicating a bad repair is bks. The 991 has less underseal on it than the previous generation cars with more plastic panels so I suspect most of those to be falling apart in 10 years time. 996s are 15-20+ years old, made from good quality steel with pretty decent, thick undersealing. However, anyone that says they don't have rust is either blind, deluded or is avoiding looking in the right places.

[LennyM1984]

nunpuncher said:

However, anyone that says they don't have rust is either blind, deluded or is avoiding looking in the right places.

I woould suspect that they are not looking in the right places. Rust that is easily visible (ie. the shiny painted bodywork) is what most people are thinking of and in my experience is pretty rare on a modern porsche. Rust underneath the car (which is where 9X6 and 9X7 cars are/will start going) is harder to spot and the only people who will notice it are those regulalrly working on their cars and/or actively looking for it

I have noticed that the 9X7 spot welds are a bit more flaky than the 996 era and the underseal near the front subframe mounts seem to be a prime spot for damage (which if left will let water get below it) but as you say, it is all just surface rust (the rust on the spot welds can be scraped off with a finger nail). My rationale for being a bit cautious in this case is that if an MOT man thught it was worth mentioning, it must look a little worse than a light surface rust. I'd therefore want to have a good look at it myself - welding in new metal is a far more significant undertaking than cleaning up surface rust and painting some epoxy over the top.

[blueovercream]

This is great all, thanks a lot.

It may all be academic anyway - the car is pretty keenly priced given the issues, viewing would certainly not be counted as an essential journey and it's not one I'd want to buy without seeing first! Maybe if it's still for sale when lockdown is lifted...

Sounds like it certainly wouldn't be cheap though perhaps not as bad as I was expecting. Probably advisable to hold out for a better one anyway.