34-PDSIT-2 Carb idle Speed screw vibrates and closes

[Pabloako]

Hi everyone,

I have found a new feature on my Type4 (1800cc) engine and the 34-PDSIT carb, where if I adjust the idle speed screw, the vibration from driving causes the screw to rotate in.   The first thing I know is that I start idling (and chugging) at about 500rpm.  If I adjust it out it is fine for a while and then rotates back in again.

Has anyone else experienced this?  Does anyone think if it would be ok to put a tiny bit of Loctite towards the top of the screw?

[Tintop]

is the o-ring missing? that usually assists in keeping it from vibrating loose

   

[Pabloako]

Ooo, thank you.  I will check.

[Barry]

As said above. 
Even if you have the O ring check to see it the sides are curved. 

Old ones will “square” off

[Oldman]

Old ones will “square” off

…..and as a result,not put any pressure on the sides, lose seal and vibrate loose…..
O rings, no matter where they are can be one of those simple fix failures.

How’d you go?

[Pabloako]

…..and as a result,not put any pressure on the sides, lose seal and vibrate loose…..
O rings, no matter where they are can be one of those simple fix failures.

How’d you go?

There is one on there, but it is showing its age and cracked.
I will go in the hunt for a new O ring.  To be honest, my bus has given me several rather expensive surprises, so this is a lovely easy and cheap one! 

Bg thank you everyone.

[Pabloako]

I finally got around to doing this, after konking out at traffic lights and roundabouts and having to jump out into the traffic with a screw driver.  At least I got a few laughs from people behind me. 

I have replaced the O-ring and a simple 5mm "petrol safe" O-Ring from Supercheap. It is all nice and snug again and doesn't move.

[Oldman]

Gotta love an easy fix