MOT Fail - car been over-revved?

[Joe_Eagles01]

After some advice on where I stand,

Took my 2015 Mazda 6 2.2 d for an MOT at the local ATS and it failed because apparently the rev limiter is defective. See below the MOT fail:

Emission control equipment obviously defective rev limiter appears to be inoperative allowing the engine to rev freely past its marked redline. therefore, emissions test abandoned due to fear of damaging the engine (8.2.2.1 (a)) - Major Emissions unable to be completed rev limiter appears to be inoperative allowing the engine to rev freely past its marked redline. therefore, emissions test abandoned due to fear of damaging the engine (8.2.2.2 (e)) - Major

They were unhelpful when collected the car - 2 hours later after no phon call. Said they can't fix stuff like that and I've got 10 days for a retest. Car felt hot upon collection but started and idled fine. After 4 miles, joining the motorway the car threw a CEL and oil light. Pulled over and let the car cool, wouldn't start at first so scanned it and found oil pressure fault code. Got the car recovered home and have left it since.

It seems too much of a coincidence that the breakdown was straight after the MOT, especially when they openly said to me that the car revved well past what the limiter should be.

The problem I have is after complaining to them and the DVLA, they accept no responsibility and said that it is standard for them to rev the car until the limiter kicks in which after speaking with multiple other independent garages is not the case when doing an MOT.

Any advice would be greatly.

Thanks,

Joe

[ARHarh]

I have never seen an MOT tester rev a car to the rev limiter, and over the last 40 + years I seen a few MOT's done. You may need to rev a car to a few thousand RPM for the emissions test, but no where near the rev limit.

I can't say whether the revving will have caused the breakdown or not, but find it unlikely.

Disclaimer ; I am not an MOT tester so could be wrong.

[Athlon]

Yes you do:

Increase the engine speed slowly to maximum engine revolutions (revs) to check that the governor is working properly


Once the engine speed has stabilized or it becomes clear that the governor is not working, release the pedal and allow the engine to return to idle.

They did it correctly as long as when they realised the engine was revving beyond it's limit they let off.

"Do not do a smoke test if the engine is not in a safe condition. You must make sure it’s safe by asking the vehicle presenter and carrying out a brief examination of the engine.

The smoke test should not be carried out if:

there is insufficient oil in the engine
the engine oil pressure is too low
there is abnormal engine noise
the governor has been tampered with
the camshaft belt is in an unsatisfactory condition"

[Joe_Eagles01]

So is the governor just another word for limiter? Is this just a bit of a grey area as I've spoken to 2 other garages who both said they never needed to hit the limiter on MOT's.

[mcflurry]

AFAIK there's a specific exclusion at many garages saying they have to rev diesel engines and there's no liability if there's an issue.

[Athlon]

Joe_Eagles01 said:

So is the governor just another word for limiter? Is this just a bit of a grey area as I've spoken to 2 other garages who both said they never needed to hit the limiter on MOT's.

Yep.

In practise most testers just bang the details into the machine, stuff the pipe up and rev the car until the machine says stop, rarely get to 3.5K that way. BUT if it is done to the letter then the governor should be tested as above. It's not a grey area, the text is from the book, it's just most of us have a bit of mechanical sympathy and a fear of grenading an engine!

[Joe_Eagles01]

Fair enough, at least I know where I stand. Thanks for the reply.

[swisstoni]

Just get it retested at a Mazda dealer.
At least they might have a clue.

[66HFM]

Try posting in the Ask an MOT inspector thread and they may be able to give you a correct answer

[Smint]

The garage have done nothing wrong, soon as they realised it had no working governer/rev limiter they stopped the test.

As said above about warning signs re MOT tests on Diesel engines, basically unless you know the engine is in good condition with a healthy cambelt best get it up to scratch before submitting, the Diesel MOT test is not gentle.

The engine in question is well known for fuel dilution issues often due to multiple failed regens (especially if the vehicle sees lots of short journeys) sometimes leading to component or engine failure.

[Athlon]

66HFM said:

Try posting in the Ask an MOT inspector thread and they may be able to give you a correct answer

That is my thread! My replies and Smint's are correct.

[Joe_Eagles01]

As long as they have not been negligent I haven't really got an issue. It seems like a legitimate defect but I haven't a clue why the rev limiter wouldn't kick in, sounds like a daft thing to map out if someone has done that? Definitely not performance mapped as the car isn't quick.

I am aware of the common issues of the 2.2d, it regens roughly every 200 miles and I drive nearly an hour each way to work so it gets a good run. I'm going to have a look at oil strainer and injector seals this weekend.

[Krikkit]

Has there been any smoke or anything recently?

Could it be that while sitting running on the ramp the engine has accumulated a bit of oil in the turbo pipework, then surged up when they revved it for the emissions test?

[Joe_Eagles01]

The tailpipe has always accumulated soot but no plumes of smoke on acceleration, only a small amount if you hard accelerate while it's doing a regen.