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21
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by philip -
Thank you very much for your very very helpful comments and video. I will study this when i have a bit more time. I see you got the same golf as mine and even the color tornado red :). I have done my test so basicly instead of driving for 20 minutes for the rpm's to drop back to normal, i started the car, ran it 10 minutes as it does at 1400 rpm+-, turned it off for 30 minutes and started it again and the idle was perfect ! So, correct me if i'm wrong but seems to me the 3 point unit is just very slow to retract ? or is it is the waxstat thing with the needle that is frozen ? I did change it 10 years ago to a metal one instead of plastic,..Food for thaughts,...Thanks again. Phil.
22
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by Keekster64 -
Ah the joys of the pierburg.  A few things to get us started.  The idle is not controlled by the choke.  Its controlled by the three point unit, and the waxstat.  When you first fire it up it should briefly reach the initial idle speed, about 1400, for a 10 secconds or so.  This is controlled by the thermo time value that adjusts the vacuum and causes the three point unit to stick out as far as it will go, which I'll call position 1, then the three point unit should retract to its middle position (position 2), at which point there will be a gap between the throttle arm and the three point unit as the waxstat will keep the idle higher.  As the waxstat warms up (check you are getting hot coolant flowing to it), it will push a pin which will cause the throttle arm to move back towards the three point unit.  When hot there should technically be no gap between the throttle arm and the three point unit.  Mine always had a gap, but I never got around the adjusting the three point unit.
The fact that it eventually drops to 900 when hot suggests that everything is working but the waxstat is slow to warm up.  To be honest, they are always a little on the slow side to warm up, but I would say 5-10 minutes is probably like normal.  Start the car on the drive cold and watch the carb go through the cycle.  Check to make sure coolant is flowing through the small hoses to the waxstat. 

Position 3 of the three point unit is when its fully retracted, which happens when the you turn the engine off causing a solenoid to close/open, and the total vacuum increases to the maximum causing the three point unit to pull back.  This causes the throttle flap to shut and the engine cuts off.

One last thing.  The choke only controls the mixture.  In my experience they tend to give far too much choke when its fired up form cold.  I backed mine off a bit, cause it ran too rich when I first fired it up, causing it to flood a bit (lower revs). The choke is controlled electronically and via the coolant.  When its cold make sure the choke is getting 12volts.  If not it will be relying on the coolant to warm up and that is waaaaaaay too slow.  Its controlled by a thermoswitch on the top hose to the radiator.  The video explains.

I did a video a while ago that explains all the parts of the carb, that you might find helpful.
https://www.youtube.com/watch?v=taTBdkrQouI&t=16s

23
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by philip -
Hi, may be i didn't explain correcty too lol. So when stone cold, start the car, rpm goes to 1100 ( auto choke i guess,.. ), i start driving and after 1 minute, the rpm goes to +- 1400. After driving for about 15 minutes when the temp is in middle and car hot enaugh, it starts to slowly drop back to normal idle within +- 5 min. To answer your question, yes, at that point if i turn off the car and resart it immedialty it idles perfect at 900 rpm and for the rest of the day until stone cold again,... And yes it should be warm enaugh long before all this,...I am going today to do another test as i might have a theory, not sure. I will drive the car for a few miles, it will idle at +- 1400 still, park, turn it off for 20 minutes and see if it goes back to 1400 rpm immediatly or if it will idle fine. I will let you know,...thank you.
24
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by scs -
Hi I obviously did not word that too well what i meant was as soon as the engine is warm enough not to need the choke if you stop the engine and restart does it run normally. The engine should be up to temp long before 20 mins.
28
New Members Say Hi! / Hello from a new Golf Mk2 enthusiast
Last post by lucaspalm -
Hi everyone, I just joined the forum after recently getting more interested in the Golf Mk2.
I really like its simple yet very characterful design. I’m currently learning more about maintenance and different engine setups. Looking forward to learning from the community