MOT advisory of corrosion to subframe

Rroff said:
This depends a lot on the vehicle, like JonRGV250 mentions - some vehicles have a know weakness and once it gets to that stage you are best looking into it, others will go on for years and years with just surface corrosion. For example I have that advisory on my D40 Navara and that it isn't wise to ignore, while if it was say a VW Amarok instead I'd not be too concerned and probably just get it cleaned and sprayed with something to protect it a bit.



Depends on the access to the subframe and what needs doing - you can have is steam cleaned and sprayed with something like Lanoguard and it will delay things a bit but it might need proper chemical dipping and/or sand blasting and proper layering up with a zinc primer and chassis paint, etc. but if there are bits which water can get into but aren't easily accessed with an easy on vehicle process they might still rot out.
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Ill have a look, although i dont really want to spend masses on the car

I am actively looking for a replacement car at the moment

This 120d i have at the moment needs bigger priority work , like new dual mass flywheel, clutch replacement,

I’m not sure if its worth sinking thousands in to this car now given its age, milage etc


My thoughts were, in a years time, would they see the advisory of the corrosion and fail it, or would it go through as an advisory again, all depends on what it looks like in a year i guess


I think if i still have the car in 6 months (probably unlikely if i buy a replacement car) although i may keep it as a backup
 
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Also by the way OP

Dec 2024, my MOT, i had to replace my two rear shock absorbers, as the previous year they came up as an advisory for leaking, and in dec 2024, they failed it based on this,

they wouldnt pass it this time, so i had to get them done. I think my bill for the MOT which included the retest, some exhaust welding , and replace rear shocks. Parts labour and vat was around £360

I'm not sure what shocks he ended up getting,. I know the motor factors well (most garages will use someone like motor parts direct, gsf or euro car parts) . It's upto you if you try and undercut abit of the part cost.and go to motorfactors to get the shocks and get the garage to fit them.. or get the.garage to source the part. In the end I got them to source it. For other work Iv had done on the car ( new bosch alternater iv gone to the motor factors first. As it's a MOT you will likely just want to sort it all through the garage
 
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DJMK4 said:
Also by the way OP

Dec 2024, my MOT, i had to replace my two rear shock absorbers, as the previous year they came up as an advisory for leaking, and in dec 2024, they failed it based on this,

they wouldnt pass it this time, so i had to get them done
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I had a bit of a weird experience with 2 failing rear shock absorbers - there was some misting but if you tried to bounce the car there was no symptoms, it was moving laterally a bit over bumps it normally went up and over fine but more noticeable it was it did this weird sinking into corners thing as if understeering only it wasn't understeering.

Annoyingly the dealer was suggesting a load of other things and a bit dismissive it could be the shocks but replacing the shocks and it completely went away. Funny thing was as well I backed it up to park to replace the shocks and they went pretty much completely at that moment - as I came to a stop I immediately noticed it and you could bounce the back easily.
 
So general consensus is get the shocks done but then have someone look at the corrosion to see if its bad enough to warrant replacement or if it needs to be treated?
 
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R.O.S.S.I said:
In particular, the most recent MOT in November the MOT had the following advisory:
  • Corrosion to rear subframe / rear wishbone arms
  • Both front shock absorbers leaking
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There’s no advisory for leaking shocks, it’s either a serious fluid leak or a light misting of oil, unless someone has added a manual advisory (which they shouldn’t do for that).
It doesn’t mean it needs urgent attention if it’s just misting or that it’ll get worse.
 
11 Nov 2023 I had these:
Monitor and repair if necessary (advisories)
  • Nearside Front Shock absorbers has light misting of oil (5.3.2 (b))
  • Offside Front Shock absorbers has light misting of oil (5.3.2 (b))
4 Nov 2024 I had these:
Monitor and repair if necessary (advisories):
  • Corrosion to rear subframe / rear wishbone arms
  • Both front shock absorbers leaking
 
The tester has put the lower two as manual advisories, which he shouldn’t have done (there’s no code after them).
We’re really only supposed to use what’s in the tick boxes and only use manual advisories for things that aren’t specifically listed.
Without actually seeing the shocks or subframe its a tough call to advise you, although as I previously said, I’d be amazed if the subframe required replacement.
 
depends how bad the rust is, if its just surface type rust, it can be mostly sanded / wire drill attatchment off and painted with a rust remover like jenolite and then painted with rust prevention undercoat and then painted with heavy duty underseal like dinitrol 4941
 
So in essence, if i had a means of getting under the car easily it'd be a fairly easy DIY job to check the subframe and treat with rust prevention stuff if it didnt look overly nackered?
 
Its also weird theyve put them as manual advisories then really, as you'd think they might have done this to try and persuade you to get some work done, but when i've called them about getting work done they said they wouldn't bother getting any work done on the car :confused::cry:
 
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R.O.S.S.I said:
Its also weird theyve put them as manual advisories then really, as you'd think they might have done this to try and persuade you to get some work done, but when i've called them about getting work done they said they wouldn't bother getting any work done on the car :confused::cry:
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Yeah, it is a bit odd.

These are the options we're supposed to use for shocks and subframes, and not use manual advisories..

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I'd find another garage to use.
 
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No idea, but if they didn’t want to fail it then why not put “light misting”? which is a correct advisory.
This is precisely why we use a tick box system, so there’s no confusion.
It either passes (with advisories) or fails.
 
OK. So back to my previous point, I presume checking a subframe for rust/corrosion is pretty easy to do myself providing I can get adequate access under the car?
I'm happy to get some new shocks if need be.
 
Yes, just stick it up on a couple of axle stands and chock the front wheels front and back.
Have a look on the internet of a similar good or heavily corroded subframe to have an idea what you’re looking at, then go for it.
If you’re not sure about anything, stick some pics up on here.
Or if you’re close to Ipswich, you’re welcome to bring it to me (no charge) and I’ll inspect it for you (you can have a look around as well).
 
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R.O.S.S.I said:
So in essence, if i had a means of getting under the car easily it'd be a fairly easy DIY job to check the subframe and treat with rust prevention stuff if it didnt look overly nackered?
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Assuming you were lucky and it was just surface rust that is mostly on the bottom half of the frame where you can get to it fairly easily, then yes you could possibly DIY it yourself with PPE such as goggles, mask, gloves. Its a pig of a job, I have done it several times and its always filthy work dealing with rust.

You will need to clean it as best as you can, then use a light and mirror to try and find any evidence of deep rust / rotting to the frame so that you dont waste you time and effort on a lost cause.

If the frame is solid with only surface rust in evidence then I would use a strong klingspore branded cloth backed wet and dry metalworking type sandpaper and some wire brush drill attatchments on a cordless drill to try and strip all the rust off or the vast majority of it.
If that went well and still no evidence of serious rust then you can carry on with the other steps.

With the dinitrol 4941 you can simply put the tin in a bucket of boiling water for 10 minutes or so to make it flow well enough to paint on with a hand brush.

This advice only works if it is caught early enough, if its too far gone then you need to replace with a either a new one or 2nd hand one that is in good condition.
 
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R.O.S.S.I said:
So general consensus is get the shocks done but then have someone look at the corrosion to see if its bad enough to warrant replacement or if it needs to be treated?
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Depends on your MOT tester to be honest and how he checked it


As said, i used one particular garage in Dec 2023, who stuck the leaky shocks down as an advisory

then in dec 2024, i took it to a completely different garage for a test, and he failed it

Another garage may have put it as an advisory again


Maybe worth seeing if it goes through or not as an advisory? but be prepared for a failure if it doesnt, then you will need to get it replaced



Same with subframe, see if you could get a garage to have a peek before the test. Although businesses want to get money from you, so chances are they will say it needs doing
 
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R.O.S.S.I said:
OK. So back to my previous point, I presume checking a subframe for rust/corrosion is pretty easy to do myself providing I can get adequate access under the car?
I'm happy to get some new shocks if need be.
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Really easy if you can get it on a lift, still doable with stands but a bit awkward, sometimes you might have an undertray or similar in the way though which is much easier again to deal with if you can get time on a lift.

It usually isn't overly difficult, just a bit of a chore, to treat it yourself in most cases - worst comes to worst a good clean and something like Lanoguard will buy time but will need reapplying - properly prepping the surface, something like high zinc primer and then an appropriate chassis paint and it will probably see out the life of the car.
 
R.O.S.S.I said:
Booked it in with someone else to do a service and the shocks. Explained about the corrosion advisory and they are going to have a look and let me know whether its bad/needs stuff doing on it.
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Let us know how you get on .I would like to know if there is any fixes for my 1 series coup without having to replace whole subframes etc

I have my own ramps so may see If I can buy some anti corrosion paint or protection and go over it. Although if an MOT tester has it up on ramps whilst testing they may get a screwdriver and knock the handle against it.. if it starts crumbling like there is no tomorrow then protection paint ain't really going to sway a decision
 
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