PIERBURG Rebuild - pre build advice

Carbs; K-jet; Tanks; Lines; Filler necks, Senders; aftermarket fuel systems; Exhausts and Manifolds;air filters - standard and aftermarket

Moderator:Scirocco Register

Forum rules
Hints, tips and guides for repair and modification - the FAQ section on the main website is worth checking first for information relating to common faults and technical help. Useful posts and guides will be added to the FAQ http://www.sciroccoregister.co.uk/scirocco-faq
h11poc
Posts:81
Joined:Sun May 16, 2021 6:37 pm
fill in the right answer:15
Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Wed Jun 02, 2021 1:19 pm

Image



h11poc
Posts:81
Joined:Sun May 16, 2021 6:37 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Wed Jun 02, 2021 1:19 pm

OMG sorry - cant get image in


https://ibb.co/bgk5Wr2

If you look at above photo you will se the spring for the lever and honestly, there is no wax stat in the world that will push that. I have to use a lot of force to turn it via its allen key. Wax stat is on top of carb



h11poc
Posts:81
Joined:Sun May 16, 2021 6:37 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Wed Jun 02, 2021 2:52 pm

One more thing... Ive scoured the manual and the internet and there is nothing to fix a Pierburg that has been totally screwed by a previous owner. Surely there is something between the white plastic part of the auto choke and the choke flap in the carb?? A spring perhaps - I have nothing.. Im almost 200 pounds on part in so far and literally everything I find online is for carbs that havent been screwed over previously...

Is there anyone on here I can send my carb to who can look at it?? Ive got all new gaskets on , the wax stat new etc... all new hoses.. i just want to drive the car lol but this carb is so frustrating and complex I literally feel depressed.. i bought the car as something to enjoy but that carb has ruined me lol... SHould i bight the bullet and but y a webber?? At least a webber works..



WreckTangle
Posts:94
Joined:Sat Dec 02, 2017 6:16 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by WreckTangle » Wed Jun 02, 2021 2:54 pm

It looks as though the pin on your wax stat is protruding more than it should at room temperature. This might explain why it pushes in when you attach it to the carb.

The adjustment you can make is not to the wax stat but to the warm-up curve it influences on the carb; i.e. for a given protrusion of the pin how much does it open the throttle and where is this on the curve. You should never try to pull the pin out manually.

The correct test for the wax stat is that when applying a compressive force of 30N (approx. 7lbf) to the pin at room temperature it should protrude 2mm +/- 1mm beyond the case. The mechanism on the carb should not exert a force in excess of this.

The test tool I alluded to above basically mimics the length of the pin under ambient temperature (2.0mm) and normal engine coolant temperature (8.15mm). You will struggle to set/check the warm-up curve without it. Have a look at section B.2.1 in the Pierburg service manual.

You would be surprised at the force the wax stat can exert. Have you ever tried manually manipulating a thermostatic valve on a domestic radiator? It's similar technology.

I can check your mechanism against one of my spare units later, but there's nothing obviously wrong with it. It may be a bit stiff from lack of use.



h11poc
Posts:81
Joined:Sun May 16, 2021 6:37 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Wed Jun 02, 2021 3:50 pm

Wrecktangle - thank you and the reason it is protruded as I ran hot water through it just before to check it worked etc.

Im still convinced the auto choke should have some sort of spring attached to the choke plate as I can see how the pull down will open the plate without something at least between the units.. I think i got frustrated because it has been over complicated so much to account for the wax stat failure and so on....
It was actually very clean when i took it apart.. not bad at all



WreckTangle
Posts:94
Joined:Sat Dec 02, 2017 6:16 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by WreckTangle » Wed Jun 02, 2021 5:11 pm

h11poc wrote:
Wed Jun 02, 2021 2:52 pm
One more thing... Ive scoured the manual and the internet and there is nothing to fix a Pierburg that has been totally screwed by a previous owner. Surely there is something between the white plastic part of the auto choke and the choke flap in the carb?? A spring perhaps - I have nothing.. Im almost 200 pounds on part in so far and literally everything I find online is for carbs that havent been screwed over previously...

Is there anyone on here I can send my carb to who can look at it?? Ive got all new gaskets on , the wax stat new etc... all new hoses.. i just want to drive the car lol but this carb is so frustrating and complex I literally feel depressed.. i bought the car as something to enjoy but that carb has ruined me lol... SHould i bight the bullet and but y a webber?? At least a webber works..
The approach is to set up each component as it should be as you rebuild the carb.

Accelerator pump
Automatic choke
Choke pulldown unit

https://youtu.be/amnqCUSTnUw

Watch this video, which I’ve recommended previously, from 25:45 for an explanation of how the automatic choke attaches. It sounds as though you may be missing the wire lever. You could probably make a replacement from suitable gauge galvanised wire if yours is lost. The little star clip is relatively unimportant once everything is assembled.

Once you’ve reattached the carb to the car you can fine tune the idle speed according to the service manual and the tips on here.

Hopefully the other settings won’t have been messed with. There is no reason why they should have been. If you get all the above working correctly anything else is likely to be the finer points of fuel economy and emissions which you’ll need to measure in order meaningfully to make adjustments.



GT_II
Posts:314
Joined:Fri Feb 24, 2017 12:18 am
fill in the right answer:15
Location:Warwickshire

Re: PIERBURG Rebuild - pre build advice

Post by GT_II » Wed Jun 02, 2021 8:09 pm

Have you seen the official service manual, which gives a step-by-step process to test and set up components in a logical order? If you've removed the carb from the engine, I'd probably start with Section B which covers checks and adjustments that are easier to carry out with the carb removed. As WreckTangle says, you probably won't need to check absolutely everything, but it is worth reading through all the steps and focus on those that you suspect may have been tampered with and those that you can easily check and/or adjust.

http://vwa1.dadoghouse.com/wp-content/u ... uction.pdf

Annoyingly the manual doesn't cover setting the basic throttle position because it states that the factory setting should never be tampered with. However, I suspect tampering with this sheared off screw is often used as a lazy way of compensating for faults elsewhere on the carb. I've certainly seen videos on Youtube that advocate adjusting this screw.

The exploded diagram on the Ruddies Berlin link may help identify any parts that may be missing, although I am not sure there is quite enough detail:

https://www.ruddies-berlin.de/Vergaser2E2.htm

In this link you will also find the correct settings data to fine tune the carb for specific models and engines, which override the settings table in the Pierburg manual. You are probably some way off needing these yet, but hopefully when you get there, you can do the translation by cross-referencing to the table in the Pierburg manual.
Last edited by GT_II on Thu Jun 03, 2021 9:54 am, edited 2 times in total.


1992 VW Scirocco GT II 1.8 90PS Brilliant Black 30k
2011 VW Caddy Van C20 Startline 1.6 TDI 102PS 60k
2015 Skoda Yeti SE Outdoor 1.2 TSI DSG 105PS 30k
2013 Fiat 500 Pop 1.2 69PS 40k
2009 VW Fox 1.2 54PS 60k
2009 Smart Fortwo Passion 1.0 mhd 71PS 25k

h11poc
Posts:81
Joined:Sun May 16, 2021 6:37 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Thu Jun 03, 2021 8:45 am

Wrecktangle and GTii - Superb links.. that's everything I needed to see and I feel a bit better today . I am indeed missing a couple of parts and if I can get this one working properly with that info then I don;t think I will ever fear a Pierburg again. I'll put up some pictures when it's almost done .

Thank you both again



h11poc
Posts:81
Joined:Sun May 16, 2021 6:37 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Fri Jun 04, 2021 2:42 pm

Hi again. I have discovered that my choke pull down unit has TWO outlets labled A and B with B being the top one. The diagrams I have seen only show one port. Where do the vacuum lines from A and B go?? I can see two ports just below the pull down unit to the left but I am unsure.

Also , as it was ran without a wax stat and auto choke I only have two coolant lines and i guess they route into the wax stat.
I just need to know the correct order for the coolant lines. I am guess it goes to choke in - choke out - wax stat in and wax stat out but does it matter which port on each unit I connect it to??

Sorry for the questions.



WreckTangle
Posts:94
Joined:Sat Dec 02, 2017 6:16 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by WreckTangle » Fri Jun 04, 2021 9:30 pm

The choke pulldown unit has two ports, A and B. A connects to a port on the carb. B connects to a T-piece on the hose from the green ball vacuum reservoir.

You should have a coolant hose, VW p/n 026121062C, that connects between the automatic choke and the wax stat. The other connections are p/n 037121057 from the automatic choke water housing to the intake manifold and p/n 026121056G from the wax stat to the metal water pipe near the block. These are available (non-OEM) quite cheaply as a set of three on eBay. However, these tend to be designed for 10mm ports and will be a tight fit on your new wax stat that will almost certainly have a 12mm hose port.



h11poc
Posts:81
Joined:Sun May 16, 2021 6:37 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Sat Jun 05, 2021 1:48 pm

Yes, the new stat does indeed have 12mm ports. I think I'll buy some quality hose and use that.

Ah - the carb has two spare vacuum inlets on the front. Shall i connect A to the left or the right one ? (when looking at the carb front).



GT_II
Posts:314
Joined:Fri Feb 24, 2017 12:18 am
fill in the right answer:15
Location:Warwickshire

Re: PIERBURG Rebuild - pre build advice

Post by GT_II » Sat Jun 05, 2021 3:18 pm

There's a schematic diagram of all the vacuum hoses in Section C of the Pierburg manual. Probably worth checking off the hoses one by one to identify the missing pieces in the jigsaw!


1992 VW Scirocco GT II 1.8 90PS Brilliant Black 30k
2011 VW Caddy Van C20 Startline 1.6 TDI 102PS 60k
2015 Skoda Yeti SE Outdoor 1.2 TSI DSG 105PS 30k
2013 Fiat 500 Pop 1.2 69PS 40k
2009 VW Fox 1.2 54PS 60k
2009 Smart Fortwo Passion 1.0 mhd 71PS 25k

h11poc
Posts:81
Joined:Sun May 16, 2021 6:37 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by h11poc » Sat Jun 05, 2021 3:53 pm

GT_II wrote:
Sat Jun 05, 2021 3:18 pm
There's a schematic diagram of all the vacuum hoses in Section C of the Pierburg manual. Probably worth checking off the hoses one by one to identify the missing pieces in the jigsaw!
Yes, thank you , I can see that , i was just a bit confused as B is the top port and that schematic looks like it sent port B to the carb ... You are right also in that I think some of the other lines that are incorrect. Its really amazing how many vac lines and parts there are.

believe me , the QUAD carb set up in the Chevrolet Corvair is way easier than this



GT_II
Posts:314
Joined:Fri Feb 24, 2017 12:18 am
fill in the right answer:15
Location:Warwickshire

Re: PIERBURG Rebuild - pre build advice

Post by GT_II » Sat Jun 05, 2021 4:21 pm

A couple of colour coded diagrams here that may help:

http://www.golfgtiforum.co.uk/index.php?topic=18871.0


1992 VW Scirocco GT II 1.8 90PS Brilliant Black 30k
2011 VW Caddy Van C20 Startline 1.6 TDI 102PS 60k
2015 Skoda Yeti SE Outdoor 1.2 TSI DSG 105PS 30k
2013 Fiat 500 Pop 1.2 69PS 40k
2009 VW Fox 1.2 54PS 60k
2009 Smart Fortwo Passion 1.0 mhd 71PS 25k

WreckTangle
Posts:94
Joined:Sat Dec 02, 2017 6:16 pm
fill in the right answer:15

Re: PIERBURG Rebuild - pre build advice

Post by WreckTangle » Sun Jun 06, 2021 7:09 pm

Presumably you realise by now that the colour-coded rings at the base of the vacuum spigots on the carb and its accoutrements provide a map of what connects to what. I think it matches the colour-coding in those drawings. The complication is that some of the tubes have T and Y pieces. Remember to put the little reducer in the port on the choke pulldown unit that connects back to the carb. I couldn’t get the pulldown unit to work reliably within tolerance without that in place. If you cannot find it, it might have migrated down the original tube.