PIERBURG Rebuild - pre build advice

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mark1gls
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Re: PIERBURG Rebuild - pre build advice

Post by mark1gls » Mon Jun 21, 2021 8:50 pm

Have a look at the spark plugs to see what they look like. Could be the timing is out as that can cause the engine to continue to run when switched off.

Some info and things to check here.
https://www.howacarworks.com/ignition-s ... running-on


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h11poc
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Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Tue Jun 22, 2021 2:32 pm

Perfect mark1 thank you. I forgot I had adjusted the timing to compensate when the Pierburg was in.
Running way better now - sitting just below 1k revs idle .
Spark plugs were completely black and coked. new plugs sorted that issue.

I have a timing light so will set timing properly then sort out the idle and mixtures on the carb.



WreckTangle
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Re: PIERBURG Rebuild - pre build advice

Post by WreckTangle » Tue Jun 22, 2021 8:54 pm

The coked-up spark plugs are consistent with the engine having been running rich which tends to happen with a faulty Pierburg. When you refurbished the Pierburg did you actually strip it down completely and clean it? There are various small holes through the casing (air corrector jets) which result in too much fuel getting to the engine if they are blocked.

While you have the Pierburg off the car is a good time thoroughly to test it and set it up correctly. One of these will be a great help in testing the three point unit and other vacuum components.

https://www.amazon.co.uk/US-PRO-Vacuum- ... B079JMTQZB

The status of the inlet manifold o-ring will not affect the Weber because it has no components that rely on a coolant feed. That is unless the o-ring has decomposed so much it causes a leak.

Personally, I loathed the way my Scirocco ran on the Weber even when it was working reasonably well. It is also manufactured to poor tolerances. Does your throttle body heater actually make contact with anything on your Weber? Mine didn’t.

Have you had to restrict the fuel return to get it to run properly? Had I decided to keep the Weber I would have probably ended up fitting a fuel pressure regulator.

Have you replaced the carb flange? If it’s original it will probably be leaking even if you cannot see the splits.

Is the flap valve in the air intake working as it should? They tend to seize up and stick in one position or another. Too much warm air will cause fuel to vaporise. This will be more of a problem with the ethanol blends that are becoming popular now. Too much cold air can lead to icing.



h11poc
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Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Wed Jun 23, 2021 10:00 am

Hi Wrecktangle. Yes, when I rebuilt the Pierburg I cleared all the airways , the carb was looking good with new gaskets etc. Everything worked except the 3PU which after doing that test only worked in two positions and sadly didnt shut the fuel off. I will put it back on once I find the 3PU at a price that's lower than an entire carb or 16v Engine !!

The weber hasn;t been tested under load yet or driven on the road but I did see a lot of posts about the welding tip trick to slow down the return fuel .

The engine is running lovely now. I put that coolant in you suggested and the oil change is today !



GT_II
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Re: PIERBURG Rebuild - pre build advice

Post by GT_II » Wed Jun 23, 2021 12:52 pm

Good to hear things are looking up. I hope you achieve the final hurdle with the Pierburg one day, though I'm guessing you'll want to take a break from that and enjoy the car for a bit.


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h11poc
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Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Wed Jun 23, 2021 1:47 pm

GT_II wrote:
Wed Jun 23, 2021 12:52 pm
Good to hear things are looking up. I hope you achieve the final hurdle with the Pierburg one day, though I'm guessing you'll want to take a break from that and enjoy the car for a bit.
Thank you GTii - Yes, some summer driving and unless a 3 PU falls into my hands it's later this year for that.

I will put some pics up in the correct section now it's almost finished.



mark1gls
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Re: PIERBURG Rebuild - pre build advice

Post by mark1gls » Wed Jul 07, 2021 2:10 pm

Not sure how much the carb is or how near you are but just spotted this.

https://vwgolfmk1.org.uk/forum/index.ph ... arb-from-a

You may not want it now your cars up and running?


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h11poc
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Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Sun Jul 11, 2021 11:00 am

Thank you mark1gls - I sent him a message so hopefully I will hear back



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Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Tue Jul 13, 2021 1:51 pm

He never got back to me so I decided as a chance to contact the previous owner who is a VW person and has had lots of Golfs and Sciroccos. He had a three point unit and for 25 pounds delivered it will soon be mine.

Just a quick point on the weber. I have not experienced the fuel starvation issue going uphill but after a half hour drive I noticed it did splutter a bit on the straight although driving with the choke out for ten seconds or so fixed that issue.. Aside from that I really cannot fault the weber but would like the Pierburg back in the car and will be interesting to see the fuel economy if it changes .. So far I have used Esso Super Unleaded and will also use that to gauge any changes when the original carb goes back on.



mark1gls
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Re: PIERBURG Rebuild - pre build advice

Post by mark1gls » Tue Jul 13, 2021 7:45 pm

Have you stuck the car on an emissions machine yet to see what the fuel mixture is like?
It maybe could be running just a little bit lean if you had to pull the choke out?

The 1st bit when you pull the choke just brings up the idle speed by move the cam for the accelerator.


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h11poc
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Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Wed Jul 14, 2021 4:38 am

Yes, it was very high during the MOT so it was adjusted in. I haven't noticed it since but I will take a longer drive today and see if it happens again.

I managed to fix the temp sensor as well which was nice.. I wasn't expecting a flood of coolant when I took the old one out ....



h11poc
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Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Thu Jul 22, 2021 10:21 pm

Quick message for Mark1gls... The seller got back to me and I am picking up the pierburg tomorrow.. well worth the purchase as it is working and complete and to say that I only paid 20 pounds for it ... So i got the three point unit for 25 and the complete pierburg for 20 so I shall not be complaining again about carbs !!! The dilemma now is do I keep this Weber on which i must say is working really well or go back to one of the complete pierburgs !!

Ive searched the posts on here but also other forums and some swear by the weber and others by the Pierburg. Personally I would take the advice of Scirocco owners over the Golf ones so if anyone has good points for either please let me know.



GT_II
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Re: PIERBURG Rebuild - pre build advice

Post by GT_II » Fri Jul 23, 2021 1:39 am

h11poc wrote:
Thu Jul 22, 2021 10:21 pm
Ive searched the posts on here but also other forums and some swear by the weber and others by the Pierburg. Personally I would take the advice of Scirocco owners over the Golf ones so if anyone has good points for either please let me know.
Not wanting to sway you, as I know the grief you have been through with the old Pierburg, and can see the logic of "If it ain't broke don't fix it".

However, my case for the Pierburg 2E2 for the record:

The 2E2 represents the culmination of years of collaboration in carburettor design between Solex/Pierburg and Volkswagen, which started with the early post-war VW Beetles and finished with this crème de la crème in carburettor technology.

Designed, developed and tested in partnership with VW to deliver fuelling optimised for each car, engine and in all conditions, it delivers better performance, smooth power delivery throughout the rev range, lower emissions, better economy and greater reliability.

Practical benefits include automatic idle speed adjustment and enrichment on warm-up and fuel cut-off on over-run to save fuel and improve engine braking.

I admit I am a little biased by my obsession with originality and admit that its complexity can also be a weakness.


1992 VW Scirocco GT II 1.8 90PS Brilliant Black 30k
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Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Fri Jul 23, 2021 8:06 am

Thank you GT_II As I now have two pierburgs I am able to test both. As i only know the weber on the car so far it would be interesting to see the difference. I have two weeks off from the 2nd August so I'm hoping to put the Pierburgs to the test then as I shouldn't have that over run issue anymore.



RussGLAuto
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Re: PIERBURG Rebuild - pre build advice

Post by RussGLAuto » Fri Jul 23, 2021 7:17 pm

I'm with GT_II on this one... I need to put this debate to bed, so here is my experience in full. It's a bit long winded, so grab your fav tipple and read on!

In the first few weeks of ownership of Gladys, it quickly became apparent that even though the early Mk2 had a relatively small fuel tank of just 40 ltrs, the fuel was disappearing at an alarming rate. There was no leaking that I could see, but the garage stank to high heaven of fuel as noted by the MOT tester and my wife Jane! Not good! Other indications that something was amiss was that on a cold start-up she sneezed out a shot of black unburned fuel from the exhaust. I put this down to the Webber carbs manual choke, perhaps I had opened it too much for a start up? It took two or three attempts to start and some juggling of the choke and throttle to get her going most days and, until warmed up, ran quite rough.
That aside, checking the fuel put in to miles covered I was only getting c.16 MPG at best. The automatic 1.6 FR engine with 85bhp should deliver around 35-7 MPG.

Hmm. I decided to put Gladys on a rolling road to find out what was going on. Cut a long drive and story short, she was only giving an asthmatic 55 bhp out at the wheels. It should have been 85. 30 horses had escaped the stable! She was also running rich, very rich. Which would explain the dirty cough on starting and the awful MPG. Now Webber sell many replacement carbs for various cars and the Scirocco is no exception. They even differentiate between a manual and auto gearbox setup. VW Heritage UK & Webber boast a plug in and play set up for their carbs and infers that they are better than the original Pierburgs:

To fit 1.6 engines with automatic transmission. This kit replaces the 2E2 Pierburg original caburettor which are known to have running problems.

They can’t even spell carburettor correctly!

The ‘problem’ they refer to above is that some otherwise excellent vehicles are being scrapped just for the want of a service/repair that few Garages can undertake. The Pierburg is an extremely good carburettor fitted to the Volkswagen range of 1600 and 1800cc engines between the years 1982 and 1992 and like all other mechanical parts, they need servicing from time to time. There are over 28 different engine codes and transmission within these years, each having different characteristics and, therefore, different requirements from the carburettor. The Pierburg carburettors are individually matched to that of the engine and there are, therefore, over 28 different versions of the Pierburg to suit the different engine code and transmission set –up.
An engine is serviced annually, why not the carb? Hence many original Pierburgs deteriorate, as would a Webber over time if not given love and attention.
As such, the Webber is certainly not a direct one for all replacement. After several hours and an assortment of different jets tried and timing fiddling, the chaps at Dennis Vessey carb specialists managed to find only 17 of the missing 30 horses.

Fast forward to August 2020 two years later, the Corona Pandemic grinding most things to a halt and my mind returned to the box still sitting in the boot with the original Pierburg Carb in it. With an idle couple of months at my disposal I decided to have a go at refitting it.

Now, I know my limitations, and this is a complex carburettor having an automatic choke. It is also a rare type, the 2B5 fitted to the early higher power FR engines that were fitted to the top of the range GL version. Not the common 2E2 fitted to later versions that Webber referred to.
I wisely decided to enlist some help which came in the form of a wonderful old chap who called himself John Smith (He refused to tell me his real name for fear of having his identity stolen. Again!) at Bromyard VW. A beautiful part of the country in the middle of nowhere. I sent the carb in the post and it only took him a week to refurbish it. It was then time to deliver the Scirocco to him to fit it. It was a three-hour drive, but Gladys completed it after the now usual rough start no problem, which did get me thinking ‘am I doing the right thing?’
Anyway, he kept Gladys for a whole month. Keeping me updated on a weekly basis on progress. Thankfully he wasn’t charging by the day! As it turned out, he found one or two other issues while he had it:

1. The one way pneumatic valve for the brake booster slave cylinder was fitted the wrong way around. Thus, not actually providing any brake boost! No wonder those brakes felt rather vague…
2. Fuel / air separator pot missing.
3. Fuel return pipe to tank therefore left unconnected.
4. Incorrect red coolant being used thus ineffective rust prevention (VW Heritage up to their old tricks again recommending G13 coolant for this engine!)
5. Vacuum line for the dash fuel econo-meter taken from the brake booster line (the one fitted the wrong way around) instead of from the carburettor.
6. Duel vacuum distributor fitted with retard connection open to atmosphere. So not actually retarding the timing automatically on acceleration.
7. Hot / Cold air valve in air box inoperative.
8. No vacuum connection from carburettor to air temperature sensor.
9. Hot air feed cardboard tube damaged.
10. Throttle Cable route to auto gearbox routed incorrectly.
11. Throttle Cable route from gearbox to carburettor routed incorrectly.
12. Throttle spring resistance far too strong.
13. Ignition timing set 14 before TDC (top dead centre). Incorrect.
14. Ignition Timing all over the place on acceleration, incorrect.

Blimey. It’s a wonder it ran at all and the result of years of monkeying be ‘experts’ who really don’t understand carburettors!
The water pump was leaking and had play in the bearings (that was replaced by a local mechanic 6 months before!). And a whine was coming from the cam belt tensioner that should have been replaced by said mechanic when changing the belt but clearly wasn’t!
No names mentioned for the now closed down local mechanic…

Finally, the call came to collect it. And my goodness, what a transformation. Power delivery was instant and with a noticeable punch! Wow, I suspected all the horses were back, with offspring! The added bonus was the manual choke had gone! She made the three-hour drive home faultlessly.
The following morning was a Sunday; a quiet drive was required I thought, relishing the thought of the newfound power on some back B roads!
Gladys started on the button, but a hundred yards down the road, the power dropped and she stalled. What the F**k?! She restarted, drove 50 yards, lost power again and stalled. After turning around, I managed to limp it home. One sick puppy.

I called John who was equally as baffled. He gave me a couple of areas to check, but all was working well. I decided to check the clear fuel filter which was newly replaced by John. I could see a number of black particles on the yellow filter which didn’t really concern me. However, on closer inspection with a torch I was horrified to find a small mound of much larger rust particles sloshing around on the bottom side.

I called John back, “Well that’s a bit of disaster for you isn’t it” he exclaimed. “But isn’t that what the filter is supposed to stop” I asked? “It won’t stop everything lad, the rust particles are probably blocking the jets” He wished me luck finding the cause and bid farewell.

Well, it wasn’t rocket science to figure out that everything upstream of the filter was now in question. I purchased a new fuel tank from VW Heritage and NOS fuel lines from Classic VW. The culprit turned out to be the hard fuel lines between the tank and filter. They were like furred arteries full of rust even though they looked perfectly OK on the outside. This rust probably came from the original fuel filler neck (that are notorious for rusting out being exposed to the elements in the rear wheel arch) and depositing the rust fallout into the fuel tank and thereon getting sucked into the fuel lines. So, with them and the tank replaced as a precaution and the carb jets blown clear she now runs beautifully, starting first time every time with no rough running.

As I mentioned before, she was checked for ‘rough running’ back in 2012, but the carb was just cleaned not curing the root cause. I guess that is why the Webber ran so rough also. The fuel smell also disappeared when the filler neck and connecting hose was also replaced.
Just goes to show, having a clean fuel system is everything… this is the reason that the majority of surviving Carb engine Scirocco’s & Golfs have had the Webber “upgrade”. It seems to be able to cope better with rust contaminated fuel at the expense of passing this rust through to the engine itself. Although why this, together with loosing c. 15-30 HP and adding a manual choke is considered an upgrade is beyond me.

Ill-informed people always blame the “far too complicated” Pierburg Carburettor as being rubbish when in actual fact, when serviced and given clean fuel, it is far, far superior in every way. VW Heritage should be ashamed of themselves for even suggesting the Webber is better!

I was disheartened to note the 'experts' in Practical Classics mag also commented a few weeks ago in an article that the Pierburg was usually replaced for a better Webber...

With advice like that, who needs enemies.

Here endeth the lesson.


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