Pierburg choke hoses

[captain Byrne]

Hi all.
Just changing my old Solex to a Pierburg 2E on a 1.9 DG. There are two water connectors on the choke housing but I'm not totally sure where the plumbing should go. I don't have the two hoses but I know one of them attaches to a steel tube along the top, but the steel tube on mine doesn't have a 'tee' so I wouldn't be able to fit it anyway. Does anyone know if:
A: I need to get a new steel tube with the right 'tee' on it? (Where do I get one?)
B: Where does the other hose go & what do I need to do to fit it?
C: Where (if anywhere) can I get the bits from?

Cheers, Pete.

[VWCamperfan]

Dont know if this piccy would help...

http://forum.club8090.co.uk/viewtopic.php?f=2&t=59886" onclick="window.open(this.href);return false;

[fairwynds]

Its peeing down out there at the moment, so Im not off to take pics of choke 'in situ', just yet.....!
However, heres a few pics that may help anybody in future when dealing with these choke units....

1) overview of choke unit, removed:


2) view of inside, before dismantling:


3) showing the 12v heating element (was broken on this one - hence the rebuild):


4) shows outer wiring loom of choke heating element:


5) shows the internal parts of the choke element:


6) shows the finished article


The 'theory bit' :

When your engine is cold, the choke is ON (ie: the choke 'flap' is in the closed position) restricting the air intake into the carburetter throat and therefore making your fuel/air mixture richer. The choke is ON because, inside the choke unit is a bi-metal strip (imagine two rulers, on on top on t'other - one made from metal that expands and contracts quicker than the other, when heated/cooled. These are fixed together and curled up like a spring, similar to that inside a clock). The trailing end of this 'spring' is fixed to the operating lever of the choke flap and the inside end is fixed to a rotable spline that is fixed by a grub screw accessible from the outside of the unit. This allows adjustment of unit.

Also inside the unit, under the spring part, is a tiny, delicate 12v heating element/coil. This is what is connected to the wire that goes to the choke housing and disappears inside it. This element is 'clamped' between two star shaped ceramic type holders and a flexy spring washer.

So..... engine is cold and choke is already ON. Start engine and 12v is passed through the little heating element, which heats the bi-metal spring and straight away starts to slowly expand it, thereby operating the choke flap and OPENING it, turning choke OFF. This happens slowly, during engine heat up phase.

Now, obviously, as engine heats up, your coolant gets hotter. This is where the little inlet and outlet metal pipes come into play (see thread starters original query). The warm/hot coolant is pumped through the choke housing (never comes into contact with the inside as its contained in a little water 'jacket') and keeps the bimetal strip expanded and therefore the choke is kept OFF during driving.

So the 12v element starts the choke turning OFF process and then the hot coolant keeps it off.

It is not unusual for the tiny element to break inside and therefore your choke will stay on longer than necessary, until engine fully up to temperature. This can cause excessive fuel use, amongst other problems.

Finally, when removing the choke unit, mark its position first. There are 3 x retaining screws fitted into 'slots' to allow adjustment (effectively you are preloading the bimetal strip when you turn the choke unit, allowing it to come ON/OFF sooner/later). Refit it to original position and test, before starting to fiddle with any adjustments.

Its quite easy to clean/check/overhaul these chokes, but they need to be adjusted carefully, to avoid a) choke not coming ON fully as engine cools right down or b) choke failing to turn OFF fully when heated up.

Ok, lesson over.... hope this helps someone?

WIKI please?

[spike blonde]

[/quote] Ok, lesson over.... hope this helps someone?

WIKI please?[/quote]


certainly helps me, bin having probs with choke not opening till engine at operating temp, kinda confirms wot i thought that the element or the wire to the element is busted, thanks for the full explanation of how it all works

[fairwynds]

Spike -
that element is everso delicate, made more so by the age of our vans I guess. When I dismantled mine it was easy to see that it had snapped off at one end. What made it 'not so bad' is that the break was at the very end of the coil. So I got my friend (a clockmaker) to drill and tap a tiny little hole and then he used a little brass screw and a washer to fashion a suitable repair. Been as good as new for 20k now! Best part - it cost nought!
Not sure if you can by new part/choke units any more, so at least this gives you an option.
FW

[captain Byrne]

Not complaining but this has gone slightly off thread.

[HarryMann]

Anyone help Capt'n Byrne on plumbing quests while I Wiki fairwynds very nice photoarticle?

[fairwynds]

Sorry I couldnt get these done earlier, but have had busy week. Work seems to get in the way sometimes!

Ok then, to answer your 'where do the hoses go' query....

1) Shows rearmost (ie rear of van) hose connected to choke unit, which is connected to the metal pipe 'T' piece you mentioned (in pic 2) WAS MARKED 'A' BUT MAY BE TOO SMALL TO READ


2) Shows the 'T' piece and the choke hose coming into it from right to left. WAS MARKED 'A' BUT MAY BE TOO SMALL TO READ


3) Shows the front (ie front of van) hose connected to choke unit, which is connected to the alloy, wide pipework that spans across the engine from head to head, and on which the carburetter is mounted (in pic 4) WAS MARKED 'B' BUT MAY BE TOO SMALL TO READ


4) Shows the pipe from pic 3, connected to the alloy, wide pipework. WAS MARKED 'B' BUT MAY BE TOO SMALL TO READ. ALLOY PIPE WAS MARKED 'C' BUT MAY BE TOO SMALL TO READ


I hope these help you. FW