Garage Misdiagnosis: Error or Rip-Off??

[Adrian E]

Since I work in this area, albeit on the legislative side I'll post some thoughts that might be useful.

The annual MOT is only a snapshot of a vehicle's condition at the absolute moment it is presented for test. You could drive it out of the lane, have a bulb fail that was working when inspected, and potentially leave the garage with an unroadworthy vehicle unless they spot it. Likewise a part that it marginal in terms of wear may pass the MOT but any sensible person would accept that the level of wear present may warrant early replacement, not waiting till it potentially fails a future MOT, or makes the car unroadworthy (i.e. dangerous and/or in breach of Construction and Use Regs).

On your specific points:

Originally Posted by YorkshireBloke

I had a new battery fitted and the friendly guys told me the 2 rears were "below MOT standard".

Today:- would pass, advisory (same as last year's MOT).

MOT - The check for tread depth is a minimum of 1.6mm over 75% of the tyre's width, with no exposed cord. Heavy wear on the outer edges is allowed so long as no cord exposed. They will measure with a depth gauge.

My view - that's a very low standard to be running a tyre down to to be marginal at MOT - in wet weather the available braking and steering effort will be much reduced as the tyre is wide enough to struggle to clear the water. Change tyres at 3mm unless heavy wear in one area dictates earlier. If they're not wearing despite use, look at the age of them (4 digit code 01-52 for week followed by short year so 0510 = week 5 of 2010). They're probably hard as nails and offer little grip.

Originally Posted by YorkshireBloke

MOT potential failure on anti roll bar bush.

Today:- "hardly worth mentioning bushes, don't recommend doing but have to say on form".

Bush wear has to be extreme to be an MOT failure. If there's no knocking then no major issue to leave it. If your pre-MOT was done on a wheels free hoist (i.e. wheels dangling in the air) then you can't test the suspension or rubber components in the suspension, as it needs load on the car and shaker plates to see any wear.

Originally Posted by YorkshireBloke

Belts over age but under mileage, need changing to avoid doom, destruction and poverty....

Previous inspection by some pals, looking down at belt say... Well, they look fine to us...

Looking at a belt is pointless. It will only look less than happy moments before it completely fails, unless it's so aged that the internal ribs start to crack and fall apart. It is more likely if the belts were done a long time ago that the tensioners will fail before the belt anyway. The only belt you can see without removing covers is the auxiliary drive belt for the power steering, air-con etc. The cambelt is fully covered. Stretching on time grounds can be OK if it was all done properly last time and your usage isn't extreme. Cambelts commonly fail when the engine/weather is cold as that's when the greatest load is on them. If stretching on time, don't go anywhere near the mileage limit as well.

I agree with comments above that the best form of pre-MOT is take it in 1 month before it expires and get a 13 month ticket if it passes. Treat any advisories as potential work items to be done at leisure, depending on severity. There's a lot on a car that isn't even looked at at MOT, though.

Be aware that a vehicle can be unroadworthy at any point after an MOT and it will potentially be an offence if stopped even with a 'valid' MOT, which ceases to be valid.