VW running on - mark
My 1.8 carb Scirocco runs on for between 5 and 10 seconds when I turn off the ignition . If I attempt to stop this by leaving the car in first gear and letting the
clutch in the car goes backwards (and forwards if in reverse gear). Does this mean that the engine is running backwards and will it cause any damage?
Thanks Mark
Re: VW running on - Don Cox
Mark
Yes you are risking damage, aside from anything else turning an engine backwards will risk causing the cam belt to step over one or two teeth which could cause the valves and pistons to meet, you know the rest.
As to what might be causing the running on I suggest you look for any hoses which should be attached to the inlet manifold being holed or detached. My information suggests you will probably have a Pierberg 2E carburettor,they are in my experience hard to get to grips with, so if proves to be this this good luck. If you love the car and can't fix the carburettor consider a change to a Weber, the one I've fitted to a similarly engined Passat fitted a dream and sorted the fast tickover problem I couldn't cure. The carb is usually flexibly mounted there so is a possibility of a leak there too, so check before you leap in to a change.

Regards

Don Cox.
Re: VW running on - phil garner
Always had loads of trouble with the Pierburg on my Golf and just changed it for a weber this weekend. What a difference! More performance, better economy and no more people looking at me when the car is still chugging along after I have got out and walking away :)

My Golf did the same as yours for many years and would idle at 2800 rpm when cold. I bought a MOT failure Golf from loot for £140 with 3 months tax which had a new Weber carb on it. Changed it for mine and sold the car to my mate for £100. Good deal for all concerned methinks.
Re: VW running on - John Slaughter
Mark

The classic cause of running on is carbon in the conbustion chambers providing a hot spot which maintains combustion. However this is more rare these days with unleaded petrol. Has the car the right plugs - if they are runing too hot they could cause the problem.

You don't want it running backwards though - the tensioners on chains or cambelts aren't designed to be used that way. Seroious damage could result.

The old Lucas rotor arms used in contact breaker type distributors used to have a long 'contact' which made sure that if the engine ran backwards the spark went to the 'previous' cylinder and stopped the engine running in the wrong direction. Doesn't work with electronic systems though.

Regards

John
Re: VW running on - Adam Going (Tune-Up Ltd)
Mark,
Don is right to suggest you look for vacuum leaks, but as well as the multitude of small-bore pipes around this carb check the larger right-angled pipe at the l/h (clutch) end of the inlet manifold that is the main vacuum take-off for the brake servo - this often implodes and then cracks. Otherwise, the most common problem on this carb is the cold-start waxstat (independant of the choke flap control) which is supposed to cancel the fast idle as the engine warms up. Make sure it is getting hot (potential coolant blockages), and thenlook for the small allen bolt that allows a small amount of adjustment by allowing the operating cam / quadrant to move relative to linkage. Once all the adjustment is used up the waxstat element can be replaced (approx £40).
Having said all of that, as others have said, this carb can be a nightmare, and my second job today is fitting a new Weber onto a Golf 1.8 !
Regards, Adam.
Re: VW running on - Mark
Thanks for the replies. I now have that age old dilemma known only to those who "enjoy" running older cars; with only 6 weeks MOT left do I "invest" some
money in it or trade it in and start again. I DO need something with 4 doors...
Thanks again, Mark
Re: VW running on - Andrew Moorey (Tune-Up Ltd.)
Don't bin it, fix it!!! (Or give it to me!)
Re: VW running on - Marcus
There is a valve on this carb whose job is to cut the fuel supply when the engine is switched off. This is causing the problem.

(aside from some carbon on a plug which glows hot enough to maintain combustion )

The valve in question is a gold coloured cylinder screwed into the carbat the bottom. it shoud be connected to a wire. Unscrew it and get an accomplice to turn the ignition on and off - the plunger should move in and out.

Now if you are looking to replace the car check out a K or L reg VW Vento, these are seriously good value at less than 2 grand.

If you need something bigger and perhaps less expensive, VW passats are also worth a look.

Cheers
Re: VW running on - Adam Going (Tune-Up Ltd)
Marcus,
Take your point, but beg to disagree a bit!! The anti run-on valve you identify is important in preventing run-on from normal idle speed, but if the idle speed at switch-off is anything more than 100rpm above normal (for whatever reason) the anti run-on valve does not, in my experience, prevent run-on as the air speed through the carb is sufficient to draw fuel from the primary main jet rather than just the idle jet (which the valve shuts off). Control of idle speed is the most critical factor in preventing run-on. The waxstat, air leaks, sticky throttle cable, and ordinary idle speed adjustments are all possible causes.
Regards, Adam
Re: VW running on - Guy L
Buy a Golf MkII 8 or 16V. They r going 4 £2-4k and I have just sold a P-reg 50k miles Pug 306 D Turbo to go back 2 a 91 H 8V Golf with 107k on the dials after owning an 87 D 16V for 60k miles until 170k before the utter cr*p Pug. You won't find a more rewarding, responsive, reliable drive in your life although *nothing* bar the utter ***p Corrado matches the driving position of the Karman Scirocco.
 

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