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Still runs rough after so much work

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Bad idle, stalling, smoke

Hi everyone, for as long as I've owned my Mk1 it has some weird engine problems. I feel I've tried almost everything and I'm at the point of taking it to a professional and spending a lot of cash but before I do that I thought I'd ask on this forum in the hope there are some VW-Veterans here with a lot more experience than me who might think of something I haven't thought of before…
The car: Mk1 Golf 1.1 GG with a Solex 31-PIC 6

Problems: - Rough idle (somewhere between 300-1300 rpm)
- Tendency to stall when letting go of the throttle when shifting for instance (warm engine = worse I think)
- Smoke, smell and little black droplets from the exhaust
The car runs great when simply driving though, no stutters or anything.

What I've tried:
- The ignition timing should be pretty decent by now, the CO-settings I've tried as good as possible by ear and the cold start idle through the manual choke has been set.
- Cleaning the carb and tried a different one (31-PICT-7)
- New vacuum-hoses, plugs, gaskets, 'carb-flange', airfilter, ignition coil, ignition points, condenser, rotor, dizzy cap, fuel filter and hoses, some new wires, good clean earth straps and a new battery.
- It sucked air through the brake booster, the 'hot-air-valve' in the airbox and the vacuum unit on the distributor: all have been fixed.
- The mech. fuel pump seems to be quite good but I've tried another one. There seems to be little to no rust/dirt in the tank and the fuel filter fills nicely to 3/4 with no dirt.
- The 'Idle-Cigar' on the side of the carb clicks and another one has been tried.
- Basically every part visible standing in front of the engine bay has at some point been replaced by a new one or another one from my collection of spares has been tried (I've even tried just swapping a spare 1.1-engine in to see if it would make a difference)

A couple weeks ago I got the impression that when after idling for a minute or two when the gas pedal is pressed a cloud of smoke could be seen from the exhaust, that in combination with 'little black droplets' from the exhaust made me think there might be oil in the combustion chamber.
So: took the cylinder head to a shop to get it flattened, replaced the headgasket, lapped the valves, changed the valve stem seals, torqued the head back to haynes specs, installed a new timing belt following the marks on the block… the car runs…  no real difference…

Long story short… I lack the experience to find this problem and driving an old car should be a pleasure not irritating.
Anyone an idea of something I'm missing?
Many thanks in advance. (especially after reading this whole story)















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How old is the exhaust or have you changed it?

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You have done a lot! I'm not familiar with your specific set up but some general guides if it's any help to you. For me it sounds carb related.
 Smoke, what colour is it, blue/ grey for oil, black too much fuel. I'd think unless you have a huge oil consumption then that's nothing to worry about. 
Droplets from the exhaust,  used to be common on older cars, mostly from condensation build up in the silencers over a period of time, being black  suggests rich mixture. Is the car run for lots of short trips or do you manage to get some longer trips to get the whole system really hot to stop this. 
Vacuum leaks, have you sprayed around the inlet/ carb area when it's running to see if there change. Disconnect the servo pipe and plug it. 
Have you done a check on the spark plugs, for mixture setting, give the car a decent run, try to keep a steady speed then find somewhere to stop and pull the plugs to check the colour, they should be a tan colour, black suggests you are too rich, white too lean
Have you had the carb ultrasonically cleaned, there are circuits for idle, running and acceleration and with the quality of fuel these days these can easily become choked if left wet over a longer period. 
Not sure if any of that's a help, or just teaching you "how to suck eggs"!

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Thanks for the replies.

  Vic the exhaust is stock and therefore probably the only original part on the car.

jakethepeg007 Sounds then like the exhaust stuff might just be an 'age problem'. I'll see if I can post a video of the car smoking here/on Youtube.
The spark plugs are generally 'ok' in terms of colour, then again the car runs great when driving normally.
I've tried multiple spray tests, the rubber between the carb and inlet manifold should be airtight as it doesnt respond to brake cleaner. The vacuumhoses should be good as well but I'll try them again soon especially the servo pipe. The carb hasnt been ultrasonically cleaned, might be worth a shot but I've tried different carbs so it would be really bad luck if they both happened to have the same problem.

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Here's a link to the 'smoke-video':
Exhaust smoke Mk1 - YouTube
It happened to idle quite good in the video but this is very inconsistent.

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It's a little difficult to say for sure but the smoke looks like condensation from the exhaust, how does it smell, cup your hand close around the end of the pipe and smell your hand after a few seconds, see also if it feels damp? 
The car sounds fairly crisp but there is a bit of a misfire there I think. Have you tried spraying some water mist over the spark plug leads and coil to see if there is any insulation break up
Check all the earth points are good also

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'Damp' is an understatement:
Exhaust Mk1 - YouTube
You can hear it misfire better in this video, could also feel the difference in the pressure from the exhaust. (The whining noise is probably the waterpump, will be fixed soon) I smell a little petrol but not 'extreme'. When smelling my hand it's a vague smell.
The droplets might be condensation and sooth then…

Still the idle (misfire) and stalling are my main concerns, I've tried the HT-lead spray before but will try again when it's dark.
All earth points have been cleaned/sanded so they should be fine as well but nothing wrong with a double check.

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White smoke from the exhaust is water, are you losing any coolant?

Not having a 1.1 car or work worked on one before this may not be right… the 1.6 and 1.8 cars have a water cooled inlet manifold so maybe yours has a slight crack causing a little coolant into the engine then getting brunt off in the engine, the crack may only appear when the inlet manifold is hot?  This is my best guess..  O_o

1988 Mk1 Golf GTi Cabriolet 1.8cc DX, K-jet. Daily drive. 317,000 miles and counting
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.

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Over on this side of the pond, the 1.8 and my 1.5 diesel if I made short jonts, then the exhaust wouldn't get hot enough to burn off all the Condesant, and would do the white smoke for about 5-10 minutes.

If I took off and got on the highway it would lessen the time it took to burn off..  Just one of the many causes for white smoke out of the exhaust.  

Another one that causes that is running a engine treatment into the air intake like SeaFoam Motor Treatment… Does kill a bunch of Mosquitoes.


What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

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mark1gls It doesn't consume coolant at all, and no bubbles visible under the radiator cap. The cylinder head has been flattened, the block cleaned and checked for flaws and the headgasket is brand new so I'm not expecting leaks there.
My inlet manifold is heated through exhaust gasses, I have seen coolant-heated ones though, got the chance to buy one quite recently.



Briano1234 The smoke sometimes stops when I take it for longer trips, by now I'm pretty convinced it's just condensation and soot (and perhaps some unburnt petrol as well?) so no more worries there…

Sprayed some water on the HT-leads and ignition coil, no sparks whatsoever, will check the cables and earth points soon but I'm a bit busy right now (exam coming up) pretty sure they're all ok though 'cause it's something I've checked and improved many times before. 

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I would say for sure that amount of water from the exhaust with the smoke from the first video that the exhaust silencer is definitely soaked, this may eventually dry out after a few long drives, but it's not something I'd worry about too much, I'd still look at the carb, strip fully  and clean (again) and add a new fuel filter between the the pump and carb I think it could be worthwhile getting an ultrasonic clean done as this should get into all the air and fuel tubes

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Have a look at the cam lobes, they can wear due to a lack of oil.

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jakethepeg007 I'll see if I can get the carb ultrasonically cleaned somewhere, personally don't think that's the problem though as I cleaned it quite thoroughly with brake cleaner and compressed air (and tried a different carb with the same issues) fuel filter is only about 1200 miles/1 Year old and clean. (Btw 'between the pump and carb'? Mine is connected before getting to the pump)



cedar The cam lobes looked fine when doing the whole 'cylinder head resto' a few weeks back. Was able to fine tune the valve clearances as well. If it is too badly worn I am not able to distinguish that so that will be something for a specialist to check if I wont be able to fix the car myself with help of the people here.

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Still runs rough after so much work

You have done a lot. Have you done a compression test?

Does it run rougher when hot vs cold - could have a crack in the block or head that opens up under heat/pressure.

You replaced the vac advance so not that. How many miles has it done ? Is there excessive play in the dizzy?

Hunting is normally as sign on air ingress and you seem to have checked for that. Maybe minor inlet manifold crack?  

Some guesses really as you have done the majority of items already.

Upside you mention you did an engine swap so you know it’s not anything to do with that, just the stuff that bolts to it. Take it to basics. Air, fuel, spark, exhaust.  Fuel seems to be sorted with the comments, exhaust not sure if an old and maybe partially blocked would cause this, spark - seems only timing could be the issue due the ware on the dizzy. Air - I would focus on this, every part connected to the inlet manifold and the manifold itself especially is worse when warm.

Good luck.


Sent from my iPhone using Tapatalk

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With the cam just have a look at the tips of the lobes where they strike the followers, it will be obvious if there is a problem there.
I mentioned this because two friends had this trouble, one with a Polo and the other with a Mk1.

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If you use a Zinc additive that prevents the wear on the cam lobes, most manufacturers of oils aren't putting Zinc in them.

What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

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cedar I'm pretty sure the cam lobes are still good but I'll check anyway soon just to be sure.


  Backinblack I have done a compression test a while back, all good. Don't think there's anything wrong with the engine itself…
The engine isn't stock and almost none of the parts are but the odometer says 120.000 miles (200k km) I'm guessing some original/second hand parts on the car are about that age.

Took my last exam yesterday, so left with some more spare time to troubleshoot.
Checked all the vacuum ports by plugging them, no difference there. Then I wanted to check on the ignition when I saw something interesting… the dizzy cap was fouled with oil… I have taken of the dizzy cap many times before in the past to replace the points, condenser and cap itself but never have I found oil in there!
Starting to think it might have something to do with the distributor then. Oil leaking through there might be a sign of too much play/wear?
Tried starting it today with a spare distributor and I felt there was a slight improvement (still a little misfire once in a while but way less hunting idle) and I haven't even set the ignition properly.
I still feel a little play on the shaft/rotor though. I would very much like to buy a new distributor (because it sure wouldn't do the car any harm) problem is: there doesn't appear to be anyone selling new/NOS distributors for the 1.1 engine. Perhaps they can be rebuild?

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My sisters first car was a Polo 1.1, we had mega issues with it misfiring and cutting out, turned out to be a bare wire inside the distributor was shorting out, I'm sure it was the wire from the points themselves, but was more than  30 years back and my memory isn't quite as good as it used to be O_o

Have a look on AUTODOC for a distributor

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jakethepeg007 Autodoc like all other sites I've searched says 'out of stock' so I'm guessing Bosch stopped supplying it all together.
There's one German site I found who sells a NOS one… costs over €200,- though, about 4x what you pay for a distributor of all the other Mk1 engines.
I prefer 'expensive' over 'unavailable' but I gotta think about it first a bit before spending that kind of money.

Currently taking apart a spare one… seeing if thoroughly cleaning might make a difference, haven't found service-kits online yet.

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I think and repeat think if you set the points with a dwell meter it should compensate for any slack in the  distributor spindle.
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