Pierburg 2E3 choke pull-down

[handsmann]

I know, I'm cringing writing this... Please bear with me. We have a 1.9 DG with a Pierburg carb that bears the label 2E and looks like every 2E3 I've seen in Haynes and elsewhere, so that's what we have.

It began the classic "chugging" over the winter and I largely ignored it because it seemed a common ailment and in the spring I was going to research the whole thing and sort it. I should say I'm not a gifted mechanic, just methodical and a bit stubborn. The fact that the van has recently failed its MOT twice on emissions has made me revisit carburation as a whole, and I have *finally* bought one of Brickwerks' modded pull-down units.

I have two questions if I may:

1 - Can the pull-down unit be swapped with the carb still on the engine?
2 - Just how is the pull-down unit actuated by vacuum? The vacuum hose from the air cleaner goes to the back of the carb and I've no idea what that vacuum actuates - it does not seem to be connected to the pull-down unit.

For folks who have worked on these carbs a lot, I apologise because these questions must seem hopelessly naive. I don't intend to do this work before our next MOT on Friday 22nd May (two days from now) in case I mess it up and end up with a non-driver. On the back of question 2, I've read about a restrictor that fits in a vacuum hose to stop the choke snapping shut, but I can't work out whether it would be in the hose from the air cleaner to the carb or in the hose which goes to the pull-down unit (the latter seems logical). In any case, I don't have this part but I've made one out of the inside of a biro - it's about 2 cm long, which is probably too long but the diameter looks right.

My knowledge of the history of this van is very sketchy, having owned it less than a year (seems like longer) so it could be that things aren't connected up correctly to start with. I'll be very grateful to anyone who can shed some light on this for me.

Thanks in anticipation...

Chris

[CJH]

It might just be possible to swap the pull-down unit with the carb in-situ, but it will be unnecessarily difficult. There's a roll pin that you have to tap out, and that will be just about doable. But there's also a sprung star washer on the side, behind the choke mechanism. Unless someone's been there before you and swapped the pull-down unit in the past without replacing that star washer (quite possible) then at the very least you'll probably need to remove the choke to get to that star washer. Actually, on second thoughts, if you can see behind the choke that the star washer isn't there, then it might actually be worth trying to remove the split pin in situ.

It's not that difficult to remove the carb though - a few electrical connections, the vacuum pipes, fuel lines, and it's best to separate the two halves of the choke (three screws) rather than disconnect the water pipes - just make sure you get the nylon pin back in the square end of the choke spring when you reassemble, and make sure you mark the choke position before disassembly. Remove the two bolts holding the throttle cable bracket, so you can separate the throttle cable from the throttle mechanism.

The restrictor has a surprisingly small hole (only really enough to get a speaker wire strand through), so I'm guessing that a biro part might not provide the same level of damping. It does go in the rubber hose between the pull-down unit and the base of the carb.

[ghost123uk]

Don't worry, these questions are perfectly acceptable

Yes the pull down unit can be changed with the carb still on the engine, but easier off.

The vac pipe to the air filter is not to do with the pull down unit. It is part of the warm air inlet system whereby in cold weather the air comes in from a heat exchanger on the exhaust, to pre warm it. This is designed to prevent carb icing up issues. However, in the UK these vans are not prone to carb icing up issues and many vans are running around with this either not working or actually removed. The heat exchanger often emits an annoying rattle, so mine is removed.

The restrictor fits in the vac pipe right where it attaches to the pull down unit. From memory, and from some pics on here (Itchyfeet pics iirc) the centre bore of the restrictor is pretty darn small. I don't think it's a critical thing though, acts as a "damper". I bet someone has one off and they van they could measure the hole

[ghost123uk]

Ha, Chris got there first

[CJH]

Ha, Chris got there first

Only just, and at least we didn't contradict each other!

[ghost123uk]

And you came up with =

it's best to separate the two halves of the choke (three screws) rather than disconnect the water pipes

11 years on and I never thought of doing it that way

[handsmann]

CJH and ghost123uk, many thanks for answering so quickly and for the wealth of detail you've given. Haynes would be about 6 inches thick if it included all this. I guess I'll just have to dream of a restrictor and smooth-operating choke

Seriously, this work will wait until after the MOT and I think I might be well advised to get a carb refurb kit while I'm at it. Just need to work out if I have a 13mm or 19mm accelerator pump rod...

Thanks again!

[CJH]

The vac pipe to the air filter is not to do with the pull down unit. It is part of the warm air inlet system...

I don't want to hijack this thread, but since we're on the subject..... If this is disconnected, does that vacuum spigot have to be blanked off? Would a leak in that part of the vacuum system cause running problems? I ask this because I currently have a high idle speed once the engine's warm and the choke (plus fast idle) has come off. Idle speed climbs to about 1150-1200 rpm, even with the idle speed adjuster backed right off. It's the same with two different carbs (one of which I've tried tweaking the idle mixture on), and with two different distributors (one of which has a brand new vacuum unit). The vacuum pipe to the distributor seems fine - the vacuum advance works as it should - but I'm nevertheless going to replace all the vacuum lines, and also the gasket between the carb and the manifold, to rule out air leaks.

Just wondering if and how the vacuum pipes at the back of the carb are linked, and whether a leak might affect the mixture.

[ghost123uk]

Ooooh, close to a thread hi-jack but vac pipe related I will keep answer brief. Yes, should be blanked off. And yes, if letting air into the carb it would cause some running problems at lower revs.

[CJH]

Thanks - ok then, if it's still doing it after I've replaced the vacuum lines and the gasket I'll start a new thread. [/hijack]

[handsmann]

Guys - hijacking this thread is welcome, because for sure I'm learning all the time. I look forward to the day that I can look at the carb and see one of The Waltons and not the spawn of Beelzebub

Well.. you know what I mean.

Chris

[kevtherev]

Chris a carburettor is just a tube that mixes fuel and air.
There's a valve to let more mixture in
And a valve to keep air out.

Walton technology right there.

[handsmann]

Chris a carburettor is just a tube that mixes fuel and air.
There's a valve to let more mixture in
And a valve to keep air out.

Walton technology right there.

Kev - your reputation precedes you. That is music to the ears of folks like me who thrive on making life harder than it needs to be

Many thanks

Chris

[kevtherev]

Chris a carburettor is just a tube that mixes fuel and air.
There's a valve to let more mixture in
And a valve to keep air out.

Walton technology right there.

Kev - your reputation precedes you. That is music to the ears of folks like me who thrive on making life harder than it needs to be

Many thanks

Chris

Aww shucks...
The rest of the stuff attached to the tube merely compensate for its failure to deal with strict emissions and extreme conditions and our desire for automation.

To enjoy the thrill of a healthy 14:1 fuel air ratio at tick over one needs a gas analyser.
As the lads have explained the pull down and its use I have nothing to add.

I have found most problems are air related ..or rather too much of it.
The pierburg is a good carburettor despite pierburgs attempts to ruin it with autochokes and pull downs

[freckvan1]

CJH what a great idea of removing Choke without disconnecting Coolant Pipes !
Thanks for sharing this and to Ghost as well .

I removed my rusty heat exchanger tin and will now follow Ghost's advice on blanking off
Spigot .
My van 1,9 DG has idling issues at start up (have to rev and set off straight away, otherwise chugs and cuts out)
I'm hoping this may help .

Chris all the best , you'll get there !

Atb,
Chris