MoT - Fact and fiction

[scaryoldcortina]

I possibly shouldn't say this, but to get the LT to pass I wind in the throttle stop so it won't rev as high. Then I get back and wind it out so it will do 60 again.

[Albert Ross]

I had a bloke get his van tested with me once, it failed on wheel bearing play and roughness, and he agreed to bring it back the next day. When it returned, it had different wheels and tyres on it. He had borrowed the wheels from a mate, and thought I wouldn't check them when he returned for retest. How wrong he was. 4 bald tyres, and one buckled wheel. HA! Gotcha. I always note the tyre tread depths, makes, and positions when testing. Also I note the DOT codes, if the tyres are the same. It helps if there's a cut/bulge etc, and they try it on...

 

Here's one. Will a car with 4 space saver tyres (All the same size) on pass or fail?

[dollywobbler]

I'm going to say it'll pass, as some joker has been selling space saver tyres as normal tyres for 2CVs recently!

[scaryoldcortina]

RFR [4.1A.1b]

[Guest Leonard Hatred]

I do bloody hate the diesel test. Imagine if they suddenly insisted that every petrol engine had to be revved to death for the MoT! Maybe I should fit a switchable rev limiter to say 4000rpm? Would that still pass?

 

It's very easy to set the 'limiter' if your BX has a Bosch injection pump, it's just a metal stopper adjusted by a screw and lock-nut IIRC. Lucas might be similar.

[dollywobbler]

RFR [4.1A.1b]

 

Ah, even more reason to lambast the person selling the spacesaver tyres then!

[CreepingJesus]

And you reminded me of a little known fact - it IS allowed for testers to test their own cars (company policy excepting) but not usual practice for obvious reasons (ever try to sell a car with the same name on the logbook as the MoT?)

I did wonder about that; the Meg had a known fault that was scrubbed off the diagnostics with a fault code reader, in order to pass its' MOT. Not by me; by a bloke in a garage, who previously owned it, bodged the warning light out, passed it, and sold it. A bit iffy, but it wasn't too serious, and was easily fixed.

[scaryoldcortina]

Engine warning light isn't covered by the MoT... nor is the airbag. Only one we give a damn about is the ABS lamp. That has to do what the VT40 says it should do (to help foil people who wired it into the glow plug circuit)

[chaseracer]

Is it true that "Mr. Hoople"'s first name was derived from the MOT?

No, Norm - but his grandad started the firm that used to coachbuild Bentleys.

 

Possibly...

[dieselnutjob]

I do bloody hate the diesel test. Imagine if they suddenly insisted that every petrol engine had to be revved to death for the MoT! Maybe I should fit a switchable rev limiter to say 4000rpm? Would that still pass?

 

It's very easy to set the 'limiter' if your BX has a Bosch injection pump, it's just a metal stopper adjusted by a screw and lock-nut IIRC. Lucas might be similar.

 

I can't adjust the rev limit easily on my HDIs as they are computer controlled. However I am wondering, if I adjust the accerelator cable so that I can only get 50% power request, presumably that will

a: acclerate the engine up to maximum less quickly which would be less of a shock loading on the cambelt etc

b: cause less fuel to be injected resulting in less smoke

 

am I right?

[Pillock]

ABS lamp....

 

That has to do what the VT40 says it should do (to help foil people who wired it into the glow plug circuit)

 

Go on then, what should it do? I thought the glowplug lamp trick was genius

[Pillock]

^^Piece of black tape over the warning lamp is the recommended repair method.

 

As far as I know, it'll fail if the lamp doesn't come on with ignition and then go out when the engine starts.

I'm figuring that the regs state that it must remain on as long as the ignition is on (as a glowplug lamp won't) - can't you piggyback it to the oil pressure or alternator warning lamps, which exhibit the same behaviour?

[Albert Ross]

The ABS lamp sequence isn't a written. all vehicles are different. Some go out with alternator light, some are timed, some go out at 5mph forwards (Land Rover). We have to ensure they follow the prescribed sequence, to which we have the information on computer, and is printed out on the Blue VT40 at time of registering the test.

[Station]

I like MOT testers who are genuinely helpful and go through all the points on your fail sheet.

If anyone's local to Birkenhead, Kelvin Service Station on Kelvin Road are like this, he has a garage with old VW's in.

[dieselnutjob]

If you remove the cable altogether, you'll have the cleanest of vehicles, very easy on shocking loads to boot, and should receive some sort of Legion of the Green Ween Award at the next convocation of the Sacred Order of the Huggers Of Trees....

 

is "no accererator cable" actually an MOT failure?

[oldford]

The accelerator cable is not a testable item, to be pedantic many cars these days do not have one. If the car cannot be driven into the testing area and is incapable of reaching the engine speeds necessary for the emissions test, then its refusal to test time.

 

For the black tape tip, I'm told that it's far less obvious if you took the trouble to dismantle the instrument panel and put the tape on the rear of the graphic between the fascia and the light source.

[Tayne]

.

[scaryoldcortina]

Would a tester be allowed to remove a piece of black tape?

 

No. not allowed to alter or remove anything during a test, especially not something stuck down. In the case of the ABS light we can fail you because we can't see the ABS light do its self-test. Remove the bulb or mask it really neatly behind the panel and you still fail. Why? because I already opened the bonnet and clocked the ABS pump, so you fail for no light again. Rather oddly though, if the light self tests fine but there is a major ABS component obviously missing it is pass/advise not fail, so if some clever so and so makes a 555 timer circuit up that mimics the self test and hides it that would pass, even if you removed the actual pump and joined up the brake pipes where it is meant to be....

[cobblers]

I'm aware that this is getting a bit "how can I cheat at ABS" but at what point does an ABS pump stop being an ABS pump and become "a valve block" IE if it's not plugged in to anything and has a sticker on it saying "valve block" and there is no ABS light on at all.

 

What if you can't see the pump (perhaps the entire area around the ABS pump is covered up with about 3 rolls of duct tape by some tightarse)

 

 

Oh, Another with regards to braking - Do the regs just want at least X amount of force from the back wheels, or do they take into account weight distribution at all?

 

I ask, because I had a Saxo VTR that had the rear brake compensator valve that more or less siezed up, so I just took the spring off and pushed it up to the "don't do a lot" position and cable tied the arm in place. The car drove fine and stopped really well. From a driving point of view it had pretty nice brake balance and I was happy driving it.

 

Some months later the car failed the MOT on the rear brakes being inefficient. I cut the cable ties holding the valve closed, pulled it open (to where it would sit when the back of the car was very loaded) and the car passed the MOT fine, but was an absolute deathtrap because even slight brake application locked the rear wheels up. Locked them quite a few times just driving to and from the MOT place!

[scaryoldcortina]

ABS - well, the VT40 sheet shows that ABS may be present on the car. It is up to the tester to decide if the car has ABS or not, and determine the test method for this. It is normally easy to tell, even if the light is not lit and the pump hidden because there is a sensor and wiring on each wheel! If you remove the system entirely, you can pass without, but if there are bits of ABS there I would expect the ABS check light to operate correctly. (If anyone wants to know how to build a circuit for less than £5 that mimics the check light on most cars though.... )

 

Brakes. no, front/rear bias is not taken into account. All you do is add the 4 wheel readings together and divide into the brake test weight of the car. Any brake recording close to zero can fail for little/no effort though.

 

PS, I have a feeling the saxo should have failed anyway, for the siezed bias valve.

[CreepingJesus]

Does one actually have to be a time-served motor vehicle technician, to be a tester?

[The Reverend Bluejeans]

(If anyone wants to know how to build a circuit for less than £5 that mimics the check light on most cars though.... )

 

 

Do tell!

 

On cars with horrid unfixable ABS, I normally just remove the ABS block and all four sensors, and make up a bridging pipe.

[scaryoldcortina]

So you want to be an MoT tester?

 

CJ, The requirements for tester training are in the link.

Rev. BJ.... I'll see what I can do later (maybe a new thread)

[Guest]

Bump for a useful thread, especially the bit on seatbelts. The Volvo's O\S belt retracts slowly but can be pulled up. It doesn't lock when spooling in and out. From what you've said I'll be fine.

 

The 480's windscreen has picked up a small chip which is smack bang in the centre of the swept wiper area. I'm a bit concerned it will spread and then it's new screen time. What's the maximum size of chip that can be filled?

 

Next question - electrics. If I can get everything to behave (and I can, stuff just needs persuading) but the blown bulb warning light doesn't go out (sometimes it does, sometimes it doesn't), will the car fail on bulbs or just get an advisory? The rear sidelights are the arseholes, they don't always come on but light up (with the high level brake light) when you hit the brake. In each rear cluster the 480 has two bulbs, one for the tail lamp and the other a combined stop \ tail lamp. They both glow brighter when the brake its pressed.

 

Full beam on the pop ups work fine, but the corresponding symbol on the dashboard doesn't come up. I can't get the long range headlights to work, and then can be switched in or switched out of the main beam by a switch. If I keep them switched out, will they only test for the full beams on the pop ups?

 

I'll break out the spook piss and see if I can get the clusters to stop impersonating a kettle. I have till March so there's plenty of time.

[worldofceri]

My Volvo has a small hole in the exhaust. It's been like that for a while now and isn't getting bigger; it doesn't sound loud even when you rev it. Will it fail?

 

My Landy got an advisory for 'minor exhaust leak' but I'm not sure that's actually correct - it should have been a fail I think. If it's really small, just a blob of weld should sort it.

 

The manual words a fail as "a major leak of exhaust gases". I wouldn't have thought a small hole would have been a major leak.

 

If a cat equipped car it may affect emissions and then it might fail under that but not for a leak of gases.

 

Cheers for the advice dudes. Seems my 'small hole' is bigger than I thought. Just got back from the garage with

 

(centre) Exhaust has a major leak of exhaust gases [7.1.2a]

 

Exhaust emissions Lambda reading after2nd fast idle outside specified limits [7.3.D.2b]

 

Ho hum.

[Father Ted]

Not using a 555 chip and piece of breadboard?

[scaryoldcortina]

Not using a 555 chip and piece of breadboard?

 

well, you could use a capacitor and a relay, but I prefer the LM555

[scaryoldcortina]

^^ no, I don't have a car with ABS, nor do I test my own It is an entirely theoretical exercise.

[capsuleboy]

A slight shift sideways...but here goes...

A 2002 Renault Avantime, lhd with a bit of tape on the headlights to alter the beam and a digital kph speedo.

Would you fail it on either of those?

A friends just brought one back to the UK and needs to register it here, so will be MOT'ing it very soon.

Does age make a difference? As all my oldies have gone through many tests like this.

Finally if it needs a mph speedo would a Tom Tom stuck on count?

[scaryoldcortina]

"beam converters" are acceptable for MoT. So is a KPH speedo (because it isn't checked) but when you go to register it the DVLA will want both RHD headlights and a MPH speedometer.