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Vented Cap - Mot Issue?


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#1 Richie83

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Posted 04 August 2019 - 06:35 PM

My pickup has a drilled vented fuel cap - it came with it. I am not sure it needs a vented cap but that’s another issue. It’s going for MOT Tuesday and last time someone told me it would fail and lent me a cap - this time I have no spare. Is a drilled vented cap an MOT failure on a 1979 mini 95 with an K1100 engine? TIA for your advice.

#2 Ethel

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Posted 04 August 2019 - 07:33 PM

There's no other vent on your tank, so the cap must be and you can't be failed on it.

#3 imack

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Posted 04 August 2019 - 08:47 PM

Totally agree with Ethel, it needs a vented cap, but how were the original van/estate caps vented, I don't remember there being a visible hole, they must have vented to the under side of the cap outside the filler neck.

#4 DeadSquare

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Posted 04 August 2019 - 08:56 PM

My pickup has a drilled vented fuel cap - it came with it. I am not sure it needs a vented cap but that’s another issue. It’s going for MOT Tuesday and last time someone told me it would fail and lent me a cap - this time I have no spare. Is a drilled vented cap an MOT failure on a 1979 mini 95 with an K1100 engine? TIA for your advice.

 

K1100 engine, or K110 head on an A series block ?



#5 unburntfuelinthemorning

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Posted 05 August 2019 - 07:19 AM

Totally agree with Ethel, it needs a vented cap, but how were the original van/estate caps vented, I don't remember there being a visible hole, they must have vented to the under side of the cap outside the filler neck.

Yes they vent to the underside.



#6 nicklouse

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Posted 05 August 2019 - 11:16 AM

Is a drilled vented cap an MOT failure.


Sounds like it. But no pics means we only see what is in our head.

#7 Richie83

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Posted 05 August 2019 - 01:45 PM

Is a drilled vented cap an MOT failure.

Sounds like it. But no pics means we only see what is in our head.

Will get one later. Imagine a normal cap with two small holes drilled all the way through from the face to the back.

#8 Richie83

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Posted 05 August 2019 - 01:47 PM


My pickup has a drilled vented fuel cap - it came with it. I am not sure it needs a vented cap but that’s another issue. It’s going for MOT Tuesday and last time someone told me it would fail and lent me a cap - this time I have no spare. Is a drilled vented cap an MOT failure on a 1979 mini 95 with an K1100 engine? TIA for your advice.


K1100 engine, or K110 head on an A series block ?
k1100 head on A series block

#9 Ethel

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Posted 05 August 2019 - 03:58 PM

You can never fail on anything that was legal when your car was made. I'm not a tester but I think the filler cap seal was added for visual inspection a few years back - that's entirely different to how the tank vents.

 

 

Inspection:

 

4. A fuel tank cap/filler neck sealing device:
a. missing
b. does not fasten/close securely: 
• by a positive means, and 
• such that pressure is not maintained on the sealing arrangement

c. sealing washer torn, deteriorated or missing, or a mounting flange/sealing method defective such that the leakage of fuel is possible

 

 

Reasons for failure:

 

4. A fuel tank cap/filler neck sealing device:
a. missing
b. does not fasten/close securely: 
• by a positive means, and 
• such that pressure is not maintained on the sealing arrangement

c. sealing washer torn, deteriorated or missing, or a mounting flange/sealing method defective such that the leakage of fuel is possible

 

Source: http://www.ukmot.com...7.2/Fuel-System

 

 

So the cap must seal on the filler neck, even if petrol can pee out of a vent hole in cap if you manage to flip your car on its head.



#10 nicklouse

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Posted 05 August 2019 - 05:04 PM

Is a drilled vented cap an MOT failure.

Sounds like it. But no pics means we only see what is in our head.

Will get one later. Imagine a normal cap with two small holes drilled all the way through from the face to the back.

That will be a fail if seen.

#11 Richie83

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Posted 05 August 2019 - 06:41 PM

Interesting. I’ll let you know how it goes and I’ve got a local lad who can whip a cap down if it fails.

#12 nicklouse

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Posted 05 August 2019 - 07:37 PM

Interesting. I’ll let you know how it goes and I’ve got a local lad who can whip a cap down if it fails.


Just get the correct vented type. That will be fine. It is the modifications with drill that will fail it. IF SEEN.

#13 DeadSquare

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Posted 05 August 2019 - 07:59 PM

Stick a label on the cap (over the hole) 

 

NO  UNLEADED  PETROL



#14 Richie83

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Posted 06 August 2019 - 06:48 PM

Long story short... it passed with the cap in place. I’ll be replacing anyway at IMM.




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