Hi. There is much on this forum about rust but something that I am not finding here, or other forums, is some idea (pictures?) of how far gone the rear arches on my NB need to be before the car it likely to fail its MOT.
Does anyone have any thoughts here? I have some rust. MOT is in December, just curious about the likelihood of an MOT failure.
The previous owner, I have only had the car 4 months, had the sills done for the last MOT and there is no chasses rot. Rear arches are the only concern I have but not having had experience with older cars before I am not sure what to expect or what is acceptable for an MOT pass.
I think they have to be corroded to the point of being dangerous (i.e. a sharp edge) before they fail it on wheel arches. The arches on my first Mk2 were really bad and they were never mentioned on an MOT.
The main area that MX5’s fail on is corrosion in an area within 30mm of the seatbelt mountings and you will have to check that distance by searching the MOT Testers Manual available online.
As the arches tend to be outwith that it tends to be the sills that cause the problem if there is corrosion in the sills.
If there is loads of rust at the arches and a sharp edge at the arches that may well be a failure.
In most of cases but not all, the rear sills are the typical MOT failure.
As they get rustier other areas will also rust through.
Thanks all for the encouraging replies. Could you perhaps explain the above in a little more detail however? I have read the details on the GOV pages and I can make sense of that, the bit that I am less sure of is the relevance of the 30mm. With the mounting point just behind the seat, why do rusted sills affect the MOT as they are over 30mm away from the mounting point; or have I misunderstood?
Hi Nathan,
the sills on most small cars usually form part of a box section (monocoque construction) as such this will be designated as
load bearing and in effect form part of the vehicles chassis.When they corrode they reduce considerably the integrity of the vehicles
outer chassis,this i hope helps to clarify the situation.
Kind Regards.
Ian.
My sons NB passed it’s mot with rusted rear wheel archs all we did was cover the rusted parts with gaffer tape to avoid any Sharpe edges.as previous people have said as long as no rust within 30cm of seat belt anchor point. Its only a temporary fix but it’s cheap and works.
Nathan, it’s 30cm (12 inches) not 30mm so the rear end of the sills are well within that range. The relevance if that if there is corrosion close to a anchor/mounting point for safety equipment then it could compromise the functioning of that equipment if there corrosion spreads. Bear in mind also that the MoT tester does not check inside the car and take up the carpets to check every area of metal so the 30cm is a proxy. If you have rust within that zone then it may result in an MoT failure. However, if there is only a small amount of corrosion then it may well be listed as an advisory. I had this with my NB a couple of years ago so had a year to get it sorted out.