Apparently many facelift 156s have poor corrosion protection. Frankly, I find it a bit of a hit or a miss.
My 2005 156 appears to still be good structurally at 120k.

If you have concerns, have a good poke about in all the areas likely. I go over my car every year. Any surface rust is cleaned off and I seal it up with zinc primer and underseal.
Further to that, check the sills and if you have concerns then use cavity wax injection.
147 outer sills do sometimes go soft.
The engine undertray is good for keeping around the engine bay in good condition. That and inner arch trims keep the chassis legs good (especially above the driveshafts).

Floors can rot but it tends to be a small area of underseal which lets moisture in and it then travels between the underseal and panel. If left unchecked, a very large area can become corroded.

A once a year a good going over in the summer months is the best defence against developing problems.
At that point, I spray a bit more ACF-50 into the sill cavities which helps stop any rust creeping up the sill bottom flange.

It's a bit of a faff but many years of attention cost the same as a single weld job so I figure it's time and money well spent.

 

my 2003 147 had gone where I have circled in red. And when I say gone, I mean totally rusted away, that entire part of the pressing needed replacing. The hole I ended up on each side with was big enough to get my hand through. Also my drivers side sill had two rust holes, each was 300mm long by 60mm wide by the time I had finished cutting back to good, clean metal. The inner sill looked fine, and the passenger side is solid.

my 1999 156 is rock solid. go figure.

 

147's have a galvanised shell. Sadly this doesn't include the floor for some unknown reason!

 

eLearn says the only part not galvanized is the roof and possibly bonnet. The problem here is galvanized doesn't mean hot dipped in actual zinc, it means electroplated. This can result in a pretty thin layer of zinc depending on how long it spent in the tank (bare minimum of time I'd have thought). On my 147 you can see where the zinc has corroded away in places not well protected by underseal/paint with rust starting. All that's left of the zinc is a *********** on the surface.

Lots of threads on the issue of rust on 147's. Lots of rust issues around the "drain holes" at the rear of the floor pan. Sills rust internally. Rust traps at the front of the rear wheel arches. Rusting subframes and many other structural parts and brackets around the engine compartment that simply weren't painted properly so the paint literally falls off in sheets after a few years. Poorly applied underseal with some cars having large areas that have nothing at all, hard to see how they made it past QA. Seems a bit hit and miss though. Maybe some of the worst cars were Friday afternoon specials.

 

On my 147 you can see where the zinc has corroded away in places not well protected by underseal/paint with rust starting. All that's left of the zinc is a *********** on the surface.

That white powder is zinc oxide and it shows that the galvanising is working - the zinc is supposed to corrode, thats the point - its sacrificial, it corrodes and forms a protective barrier of zinc oxide over the steel, preventing the steel from forming iron oxide.

 

I have not owned a 147, but my final 156 (2001 car owned in 2010) was very rusty.

It seems that some cars are much more badly affected than others.

A mate of mine has a 2005 Facelift 156 and despite the car being neglected it has no signs of rust.

Also try and buy a car which hasn't lived its life near the seaside.

 

The big problem with galvanised car bodies is that they are not galvanised as an entity, they are made from galvanised sheet steel. The top & bottom surfaces of each pressing have a protective coating, but the edges have the mild steel exposed.

If the edges are not properly protected, or the protective coating deteriorates, water can come into contact with the exposed edges, maybe even be held there by, for example, peeling underseal, which means that rust will start at the edge & creep under the galvanised layer. In this situation galvanisation can actually make the problem worse, as it can hide corrosion until it's too late.

I had an MoT advisory for corrosion in the floor of my 145. Fortunately the rust was only on the surface so I was able to treat it in time, but I was able to peel the galvanised layer back 50-75mm from areas which at a casual glance looked unaffected.

 

Bear in mind the age of these cars. Most are into the 10-15 year old age bracket now. That's twice the life expectancy of a 1970s British car. I'm often amazed how cars over 10 years old are still advertised for £4000.

As echoed by others, it's pot luck and comes down to thoroughness of factory operatives and the car's environment.

A car which is still good would benefit from what I suggested but even then, a daily driver will have a lifetime of 15-20 years at best.

My other 156 is a 1999. So far it's testimony to a reasonably well built car and what can be achieved with a welding course, a decent MIG welder and diligent work with the old favourite- an angle grinder.

I think that often, Alfas defy industry norm and the early cars are often the best built ones. Rightly or wrongly, I like many people involved in production take or took a real pride in their contributions to making these flawed but iconic cars.

 

I think a lot of it is how well the shells were prepared before painting. In many cases: very poorly. Paint not actually stuck to the surface... I once had the front carpet lifted to look at the floors, before putting it back I hoovered the metal floor and the paint came away in sheets..,,,!!!

So yes, so much is down to luck.

 

Even the newest 147's are getting near 10 years old. At that age rust is possible in any of them.

 

My sills have gone and its a worry for the next MOT

My question is, on a 2 door 147 can you buy a new sill or do i have to buy a comlpete new side ?

 

One of the floor plates in my 156 had some serious corrosion and needed some TLC to repair it. My old 147 which had no underseal to speak of when I bought it had no rust issues at all. Odd. +1 for good fortune. :thumbs:

 

A friend of mine whos got 30 years of bodywork hates underseal, he says it traps moisture between it and the metal causing it to rust, he prefers stone chip.

 

In my experience the underside of 147s and 156s will be very rusty. The plus side is that the bodywork topside tends to fair very well and the paint is good. Repairing the underside of the car is considerably easier than dealing with the pretty bits up top so I wouldn't be concerned about buying an alfa that needed a little work on the sills or floor pans if it was cheap and otherwise looking smart.

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My 2004 car is pretty much rust free underneath (just a few teeny tiny spots of surface rust) despite living near the sea for the last 8 years.