Pierburg 2E3 choke

[Mocki]

Yep, my gaskets are just greased as well.... I suspect that maybe I'll have to use sealant to give me peace of mind on this one though....

[itchyfeet]

Test drive today and much better with a fresh greased gasket
I bet most of us never change the gasket, probably should every time.
I was also careful to tighten the carb down evenly in stages I wonder if it could be at a slight angle if you dont

Still a hesitation before the second barrel opens sometimes but this spare carb has alwas done that.

On closer inspection origional carb has never had the rebuild kit done so thats to do next.

[CJH]

You may be right about the carb to manifold gaskets. I replaced mine today. I made sure that all the mating faces were clean, and I used only grease on the gaskets. I also stripped the carb down and made sure everything was spotless, and I used a strand of wire to make sure all the jets were clear. I blew compressed air down everywhere that looked like an airway or petrol pathway. My idle cutoff valve seems to be working properly and seals nicely now. I also adjusted the accelerator pump cam to the midpoint, so there's no slack in the pump lever but also there's plenty of travel during the pump action.

So it should all be perfect.

And it is, nearly. Once it's warm it drives smoothly, with no sign of the hesitation/dead spot when pulling away. I suspect that's mostly down to putting the accelerator pump cam back to it's middle setting. The idle speed is a touch high, but that can easily be adjusted once everything else is ok.

But there are two problems, which are possibly the same problem. Firstly, when it's warm and running, the idle is still not smooth, and nor is it smooth when coasting off the throttle. If I apply the throttle it's all good again.

Secondly, I went out to it after the engine had cooled down and tried to start it from cold. It starts fine, but won't idle long enough for me to go from the ignition key to the engine bay to grab the throttle linkage. Even when it's been running long enough for the choke flap to open (due to the electric heating element) it does the same. I've tried the idle/CO2 screw all the way in, a long way out, and at all points in between. I also removed it to make sure it was clean. I also removed the idle jet to make sure it's clear. I now suspect there may be a blockage of some sort in the idle circuit, possibly the gasket isn't aligned properly, or perhaps there's aluminium corrosion in the pathway inside the casting - I don't know the history of this carb and have never had it running properly on my engine, so I can't rule anything out. That's tomorrow taken care of.

[CJH]

Still a hesitation before the second barrel opens sometimes but this spare carb has alwas done that.

Is it possible the socket on the end of the arm that's attached to the secondary throttle diaphragm needs some adjustment? Is the diaphragm working OK under vacuum?

[CJH]

Well I took it apart again and checked the idle circuit for blockages - all seemed fine. So then I started to go through the list of adjustments in the 'maintenance and repair' guide - I did as many as I could manage/understand. And I think the cold starting problem was simply down to the choke pull-down unit. It is a new one, but I had evidently not adjusted it in any way, and the screw was done up so tight there was zero movement under vacuum. I fixed that, put it all back together, and it started and ran first time from cold.

As it warmed up I watched the choke come off, and I adjusted the idle speed. Seems a bit smoother now, but still not as good as my 'normal' carb. And on the road the hesitation has returned a bit - not as bad as initially, but yesterday it had gone altogether, and I didn't think I'd changed anything that would affect that - certainly didn't touch the accelerator pump cam.

So what I've learned is that I now know enough about these carbs to alter their behaviour significantly, but still not enough to get them right. And I've also learned that there's virtually no way that my less-than-perfect idling, and hesitation when pulling away, can be due to the plastic parts I've made, which seem to be working fine. And since that was the whole purpose of fitting this 'test' carb I'm now going to put my 'normal' carb back on and get back on with something else!

[CJH]

'Normal' carb still idles and drives as smoothly as I remember. I'd half hoped that there was a mysterious new ignition problem that might have explained the rough idling on the 'test' carb, but I'll settle for having a smooth engine again.

[kevtherev]

Just goes to show a "proper" refurbishment at Bromyard VW can make a big difference.
It's expensive but utterly thorough.

[CJH]

True - to know that it's going to come back properly set up is something worth paying for.

Still, it's frustrating that even after being fairly meticulous myself I can't get it right. There are still some checks I haven't done yet, checks that I skipped because they seemed too difficult. I didn't check the float valve and float level for instance (and a leaky float valve is a possible cause of rough idling according the the troubleshooting table in the maintenance and repair document), and I didn't measure the volume of fuel pumped by the accelerator pump. But I reckon I can tackle those at my leisure now the carb is out of the van.

I've been out in the van this afternoon since refitting the 'normal' carb, and it drives great, but I realise that the differences compared to the 'test' carb aren't huge. The idle is definitely smoother, but it's not night and day. And there's a touch of hesitation as I pull away, but I realise that I now naturally compensate for that with the gas pedal without even thinking about it. As I found when I fitted the LT carb for a while, it's very difficult to compare different setups by the 'seat of the pants' method.

[kevtherev]

When you see this list from Bromyard for the 2e3...


3-point unit piston shut-off position mm

3-point unit piston idle position mm

3-point unit Vacuum mmHg
Internal cleanse
External cleanse
Jet stage 1 and 2
Jet cleanse 1 and 2
Air correction jet
Idle jet
Air mixture jet cleanse
Air mixture screw & holder cleanse
Air mixture jet seal
Float height mm
Float valve closure
Float weight gms
Wax-stat pushrod movement
Waxstat internal cleanse
Waxstat internal setting mm
Waxstat protrusion 30Nm at 20degC mm
Wax-stat operation on warm-up
Fast idle setting- waxstat cam 8.15mm insert
Stage 1 throttle plate movement
Stage 1 throttle plate setting mm
Stage 2 throttle plate movement
Stage 2 throttle plate setting mm
Stage 2 lock levers setting 'a' mm
Stage 2 lock levers setting 'b' mm
Choke shaft rotation
Needle valve
Enrichment valve cleanse
Enrichment valve diaphragms
Enrichment valve spring
Accelerator pump jet
Accelerator pump jet diaphragm
Accelerator pump jet valves and spring
Accelerator pump jet cleanse

Accelerator pump output cc
Main gasket condition
Channel heater cable insulation
Channel heater resistance ohms
Thermo time valve resistance ohms
Thermo time valve below 15deg C mmHg
Thermo time valve above 15deg C mm Hg
Solenoid valve electrical operation
Vacuum reading sol. valve 0 volts mmHg
Vacuum reading sol. valve 12 volts mmHg
Stop end hose condition
Vacuum hose condition
Pull down unit vacuum mmHg
Pull down unit Stage 1 setting mm
Pull down unit Stage 2 setting mm
De-choke mm
Choke electrical resistance ohms
Choke electrical operation
Choke water flow
Nominal fast idle rpm
Hot idle speed rpm
Fast idle speed rpm
Temperature sender @70degC ohms
CO reading @ idle % vol ppm
Water leaks

Final test from cold


Road test to include tests on

1) smooth and correct tick-over at cold at start

2) smooth and correct acceleration in all gears irrespective of temperature

3) smooth deceleration in 3rd and 2nd gears

4) return to correct idle at hot on sudden braking to a stop

5) smooth running of vehicle in 4th gear at 25mph and with no falter or lurch forward

6) smooth and correct tick-over at hot idle on conclusion of test

[CJH]

Impressive list. I wondered how they checked all the 'running' settings - they obviously have a van to try it on. I'd love to watch the whole process from start to finish.

[kevtherev]

Impressive list. I wondered how they checked all the 'running' settings - they obviously have a van to try it on. I'd love to watch the whole process from start to finish.

Indeed, they must have loads of data regarding running specs
With that data base it's down to methodical test and replace/clean until each components performs within its perameters.
That takes tooling and some knowledge, hence the eyewatering fee

[CJH]

I've ordered a cheapo vacuum pump and some 5ml syringes to tackle some of the tests/adjustments that need measurements - last go at trying get this test carb running properly.

[CJH]

Any thoughts as to what 'measuring device MP 1-505' actually measures, and how? With a target value of just 0.08mm I'm guessing it's the gap at the edge of the secondary throttle flap, but it's not clear why such a bulky device is needed, or why a feeler gauge wouldn't work. I guess it might be measuring the movement of the flap as the screw is wound in - i.e. wind the screw off completely, then wind it in until the edge of the flap moves by 0.08mm.

[ian prior]

Hello all

Well, the garage is half way there with our van’s choke problem! The lever that CJH kindly supplied fitted and works just fine (thanks again, CJH) – now it looks like the Bi-metal choke isn’t working correctly. The engine starts on choke without any problem, and happily sits on fast idle, right up until the moment that the throttle is touched – at which point, the choke shuts off completely, and the engine stalls. Gowers and Lee can’t supply the Bi-metal choke, as it’s no longer manufactured, so I’m looking for one second hand. Does anyone have one, or know a good source, please? Three pictures attached; Gowers and Lee say the Pierburg part number is 4.07262.54.0. Thanks again!

Ian.

[itchyfeet]

https://www.brickwerks.co.uk/automatic- ... ettor.html" onclick="window.open(this.href);return false;

Brickwerks did have them but showing out of stock
send them an email tgey may be able to get you one