Mk 1 Cabriolet Pierburg to Weber Conversion

I moved to Cyprus 20 years ago and brought my 1990 Mk 1 Clipper automatic with me - only 57,000 miles since new showing on the odo.

The expansion element (waxstat) was changed by VW 25 years ago but I believe that it is playing up again - fast idle at 1800 rpm and overrun when I switch the engine off.

The Pierburg had new gaskets fitted by the local garage in my village to stop a fuel leak and the old man seemed to know what he was doing despite the language barrier.

I do not have a garage so I cannot play with the element.  I am going to ask him to remove the element, give it to me to plunge in boiling water, then refit it.  If this does not work then a Weber conversion seems to be the way forward.

I note the Weber has a manual choke.  Is there any drilling involved or does it slide through somewhere?  Where is the best place on the dasboard for it?  I am a little hesitant to let Costas just "drill, baby drill".

Any advice greatly appreciated.

I can't help with Weber conversion, but have some experience on the Pierburg 2E2. Is the idle speed excessive in all conditions or just during warm-up? Do the coolant hoses feeding the wax stat and choke get hot as the engine warms up? A blockage in that coolant path would interfere with both wax stat and choke operation  Corrosion byproducts in the coolant channel of the choke housing caused mine to idle excessively high through and after warm up.

Overrun after switch-off doesn't sound like a wax stat issue

typ_53b said

I can't help with Weber conversion, but have some experience on the Pierburg 2E2. Is the idle speed excessive in all conditions or just during warm-up?

All conditions

 Do the coolant hoses feeding the wax stat and choke get hot as the engine warms up?

Yes!

A blockage in that coolant path would interfere with both wax stat and choke operation  Corrosion byproducts in the coolant channel of the choke housing caused mine to idle excessively high through and after warm up.

Overrun after switch-off doesn't sound like a wax stat issue

Thanks for posting.

Yeah, a faulty wax stat may well cause the fast idle issue. I'm a bit dubious about the benefit of immersing it in hot water - the coolant flow should approach 90 degrees or so when the engine is run to full temperature.

However, as you also have a problem over-running , I am wondering if both issues could be caused by a fault related to the 4-point unit (throttle plate actuator), which would likely be vacuum related.

This relatively recent video gives an overview of idle speed control components on the 2E2 carburettor and highlights a few easy observations you can make to check they are working properly - probably the most informative and accurate explanatory video I have seen on this topic:

Pierburg 2e2 carb, function and problem solving - YouTube

typ_53b said

Yeah, a faulty wax stat may well cause the fast idle issue. I'm a bit dubious about the benefit of immersing it in hot water - the coolant flow should approach 90 degrees or so when the engine is run to full temperature.

However, as you also have a problem over-running , I am wondering if both issues could be caused by a fault related to the 4-point unit (throttle plate actuator), which would likely be vacuum related.

This relatively recent video gives an overview of idle speed control components on the 2E2 carburettor and highlights a few easy observations you can make to check they are working properly - probably the most informative and accurate explanatory video I have seen on this topic:

Pierburg 2e2 carb, function and problem solving - YouTube

Thank you again for posting.

I was wrong in my previous repy - the choke gets warm but not hot.  I am off on holiday tomorrow so research will have to wait until I get back in 6 weeks.

Thank you for the link!