28 PICT: Oring needed on starter?

[herbie1200]

Dismantled my 28pict for cleaning.

I'm in doubt about the piston that moves this little arm:

This is a small piston moved by depressure, its function is to eliminate starter action (when engaged) when gas pedal is depressed, probably to avoid an excessive enrichment under load.

The piston was stuck and the small duct was obstructed, so I cleaned all.

My question: this item:

has a groove... should it be filled with an oring? I did not found worn orings but I don't know if it has been removed or corroded into fuel.

An oring should be useful because on the left part there is depression, and the piston should work sealed.

But an oring could cause an excessive resistance to starter movement...

Any opinion?

Thank you

[KTPhil]

Doesn't look like it:

p.s., For the USA folks, in Europe the carburetor choke is often referred to as the starter or strangler.

[Denny B]

Is #187 an O Ring?

[Eric&Barb]

[ddweave]

When you say starter are you referring to the choke?

[glutamodo]

In other countries that is a term they use for choke. The "T" in PICT stands for "thermostarter"

And there is no O-ring on that piston.

_________________
Andy T.


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[herbie1200]

Sorry for my mistake, in Italy we use "starter" for the carburetor enrichment; the word "starter" sounds as an english term so I thought it was OK in an US forum.

The thing I supposed had to be an o-ring is the item n.151 in the KtPhil's design.

Thank you glutamodo, the pictures you post seems to indicate that no oring is required.

BUT... I have time so spent some time to mount one oring

I had to modify a little the oring to permit a good piston moving.

The first impression: now the starter (the automatic chocke!) has a little difficulty to "engage" the cold position... I wil test a few days then decide if remove or mantain the oring.

This is an opportunity to look at the piston working without the final cover, verifying if it moves and has some utility.

I will post my results.

Thank you,

Simone

[glutamodo]

VW replaced that choke pull-off design pretty quickly for a reason I think, they came up with something better, both with a better heating element and a better, more easily serviced pull-back diaphragm setup.

I went to a PICT-1 top on my 28PICT carb decades ago.

Yes, that piston is pretty much a metal plug in a metal shaft and any kind of gunk in there will impede its movement. I think an O-ring might be more detrimental than helpful.
_________________
Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.

[herbie1200]

OK, thanks to all.

I removed the o-ring on the chocke pull-off piston because the heated spring is not strong enough to engage the chocking when cold.

Then made my test and all seems to work: with engine running and chocke 'on' (detached the connector to keep it on) the valve is visibly pulled by the piston when rpm are increased.

[glutamodo]

Sounds good then!
_________________
Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.

[herbie1200]

Yes, all seems to work.

I used a different way to remove the plug: instead of drilling it, destroying the item, I simply pushed the leg of the piston outward, a little force has been enough to make the plug "jumping" out of its seat.

[KTPhil]

[glutamodo]

Yeah it's not like VW didn't specify that the end cap of that "cylinder" should be installed with "sealing compound".
_________________
Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.