MOT Failure -- seeking some advice please.

[TrumpetMan]

Hi all,

well after a few years of care free MOT testing came to end with a bang!

I have managed to rectify a couple of the issues but there are two outstanding.

1. and it's a minor one, is that I need to acquire a handbrake cable bracket for under the van, any advice where to source one or if there is an alternative option.

2. And the biggest worry is the failure on the grounds of the emission test...Hydrocarbon maximum allowed 1200ppm and mine run in at 2924!!! However the CO was well with range! I am a little confused how it can be running so bad and not sure where to start. I have recently given it a full service new plugs, filters and oil! really not sure where to start!

The van is a 1982 2.0ltr Aircooled lump.

Help please will be much appreciated.

[billy739]

hc is unburnt fuel


did they take the revs up a little to see if it changed

from the testers manual...

Note: If a vehicle meets the CO requirement at its normal idling speed but fails the HC check, re-check the HC level at a high idle speed of 2000rpm. If the HC reading is 1200 ppm or less, the vehicle will meet both the CO and HC requirements.

what is the ha/brake bracket you refer too? hold cable in place on the arm , balance bar?

[TrumpetMan]

The cable clip that ties the cable to the dragging arm, on the other side it looks like a kinda push fit ring that tidies the cable up.

http://www.vwheritage.com/vw_spares_NCA ... try_GB.htm

looks like it but out of stock.

Yes I believe he took the revs upto 2000rpm.

The CO reading was 0.080 max being 4.500
HC level was 2924 max being 1200
Passed both idle speed and smoke level.

[billy739]

that co% is very low.

should be 2.5% from memory

try riching it up

check for an air leak or similar. you may have other problems are you certain its running on all 4?

have you serviced the engine lately?

how does it drive? should easily pull any speed limit

running lean can cause it to run hot which is never good for an Aircooled motor- dropping valves/ melted piston or heads ect

[fullsunian]

That sounds like an air leak, like Billy says, somewhere in the air/fuel intake system. The most common reason for high HC's, even a slight exhaust blow can put the HC's up too..
Ian

[California Dreamin]

Hydrocarbons can also be excessive oil burning........

What oil did you use for the recent change? I would be tempted to refill with old fashioned 20W50 if it already isn't.

That CO is unbelievable...by that I mean impossibly unbelievable as in it wouldn't run.... unless you're on LPG of course.

Needs tweaking up to 2%.

Martin

[TrumpetMan]

Hiya Billy,

yes running on all 4 cylinders the far right plug was slightly rich running when changed.

engine recently had new filters, oil, plugs etc, timing was also done.

it's driving pretty much as it always have done, occasionally stalls when cold.


Hiya Ian,

have checked the exhaust over fully and can't find any blowing from anywhere.

all pipes/breathers look good with no obvious signs of perishing etc.

Hiya Martin,

yup it's running! Oil used was Morris Engine Oil 20/50w, best way to tweak of the CO is???

Thank you all for your questions and suggestions

[lefty67]

have you checked the ends of the vacuum pipes, when I first got my Aircooled evry single one was split at the end or missing. made a big difference when done. now its part of my routine check before any long journey.

[TrumpetMan]

Well just as a brief update and to close the topic ...the bus passed it's MOT.

The problem with emissions was the Venturi Screw on left carb somehow had worked loose and fallen out hence the air leak, with it replace emissions came out as:

CO 1.553 & HC 232

a massive improvement! and a pass for another year

[CovKid]

For the handbrake cable, just fit a simple 'P' clip or similar fastener used to hold say brake pipe or hose in place. They just want to see that its secure and not bashing against the bodywork and potentially wear through the cable. It doesn't have to be an original part. A self tapper screwed into the original hole should hold it in place. You could even use a cable tie providing it is nice and secure but a P clip would show you'd made an effort.