How to inspect : Rear Sub-frame is corroded but structural rigidity is not significantly reduced (6.1.1 (c) (i))

[smudge1]

Hi .

I'm just about to look over a Octavia for sale  ( I'm upgrading from a MK1 ) which has the advisory of  " Rear Sub-frame is corroded but structural rigidity is not significantly reduced (6.1.1 (c) (i))" .

I wondered  if anyone had advice on what to look for or any particular areas to inspect ? Any photos would be appreciated . I'm also assuming that if I get it wrong , it will be an expensive repair .  I'm hoping its just surface rust that can be treated with something like ACF-50.  

 

Extra info 80K miles and also history of " Offside Rear Tyre worn close to legal limit/worn on edge 205/55/16 91V (5.2.3 (e))"  Could that also be related to rear tracking ?

Many thanks in advance.

[petrolbloke]

Difficult to properly check with the wheels on the ground. The best you can really do is look under there with a torch and try to gauge how corroded things look. Maybe the car has spent a lot of time near the sea or been driven on a lot of salted roads in the winter. It could be nothing to worry about or it could be an expensive repair a few years down the line.

 

What you said about the tyre sounds like an MOT advisory. It might have been replaced, or previously been on the front (where uneven wear on the inner or outer edges is more common). Rear suspension shouldn't really go out of alignment unless bushes are totally knackered or it's had a significant impact on that corner.

 

Is it from a dealer or private seller?

[Dooge]

Is this a VRS or standard model? Multilink suspension or torsion beam? 

 

My 2015 has a corroded rear subframe, though it's never flagged on an MOT. If it's multilink chances are the adjustment bolts for camber and toe are seized too as this is very common. 

 

The complex part is getting everything down to do a proper job. Its almost as easy to buy a second hand part and renew it but definitely not cheap. When I set up a topic on it awhile back someone said they have done a few for customers and they charged in the region of £1000. This was fully rebuilding, new bushes, arms, etc. 

 

As above though, without seeing it I can't see if it's serious or not as even opinion by MOT tester differs.

[gm73]

The rear subframe on the MK3 is trailing arms with tubular structure much like the MK5 Fiesta. If it’s corroded but not structurally reduced then I’d imagine it will be surface rust that can be treated with Kurust then undersealed. 

[smudge1]

Thanks for your replies guys.

Having studied the MOT history a little further I find that this advisory is only on the last MOT of  Nov 23 and not on any previous ones .  So its had a year and 10K to rust but  fingers crossed -surface rust. 

 

In answer to your questions :-

 

1.     It is a small dealer but not a main dealer . 

2.     2.0 TDI Elegance  83K on the  clock 

3. "  Multilink suspension or torsion beam? "   that's a question that I don't have an answer 😞 ,  but it has an engine number code of  CHFC  which a EBAY search brings up a picture as attached

 

     I assume a " £1000 "  repair cost was for the ,more complex Vrs type ?  

 

Fully appreciate you cant say too much without seeing it.  I just wondered if as I've  an inspection scope , if there were any weak spots to look at .

 

Now , it could be I'm over thinking  🙂 it so I just need to get there and make a judgment . 

Cheers 

 

 

[Nogrille]

it will probably just be surface rust.  the black "painted" parts are not painted very well, at all

[xman]

Rusty suspension components are common and in many cases the suspension parts are beefy enough for it not to be a problem.

 

However

 

1) If an MOT tester feels they need to give an unusual advisory, it could be at a far more advanced stage of corrosion than the norm

 

2) Once on an MOT history, it will put most buyers off unless you can prove its been replaced with a new part not just bodged.

 

3) Some parts of that subframe are not all that substantial. I've seen pictures of catastrophic failures due to rust where parts are welded together though not on an Octavia 3, which should be too young.

 

4) Abnormal wear on the inside of the tyre is usually related to camber or tracking. Riding on a broken spring, or wear in bushes. Could be unseen issues that need fixing.

 

Maybe its had a hard life, got lots of miles, not been cared for. Personally I'd just steer clear and look for another car.

 

 

Edited 8 March by xman

[RoddersUK]

Every time I service the car, I spray all underneath with undercoat, or spam with wax oil.

Just find with all modern cars, the black paint (if it can be called that) just disappears and leaves bear metal.

[smudge1]

Thanks for the extra information Xman and RoddersUK  .  As it happens I didn't get a chance to view as it was sold before I could get there. Lucky escape perhaps 🙂 

But as always , learnt a few things from this thread and hopefully it'll benefit others as well .

 

My search continues 🙂