Carburrettors - faults and faultfinding
by Dud » Wiki'd by mocki
I have a 2l Aircooled, and a little machined hole (which could possibly have had something fall off?????) behind the bypass idle cut off valve on the left carb has just started making a very load air sucking noise (audiable in the cab with the window shut). When I put my finger over it at tickover it raises the rev's slightly.
I have just disconected the bypass idle cut off valve by pulling out the power lead on the left of it. This has drastically reduced the sucking and therefore the sucking noise. From what I understand the point in this valve is really to stop the engine running or causing backfire once the ignition has been turned off, a problem on the Aircooled's due to hot spots. Is this correct????? I am also keen to know if in temporarily disconnecting it there will not be any major issues other than those mentioned above, or other damage as a result of me disconnecting it? (I'm planning to go away in it on monday for a week).
Secondly, does anybody have any idea why it has suddenly started making this sound? Could the valve be faulty? Could something have fallen off that was covering the hole making the noise (I did find a paper hole punch shape and sized bit of metal nearby in the engine bay)?
Many thanks for any replies.(82 Aircooled Autosleeper) Dud
Posts: 94 Joined: 17th, Dec 2005 Location: Portsmouth Member No. 2029 80-90 Mem No: 2029
Reply by Steve8090
You should have a little steel disk fitted to that hole, there are actually two of those, they are machining holes that are blanked, similar to core plugs, it is quite common for these to fall out, you will need to block this up with a similar flat disk, if you dont want to take the carb off then use some 5 minitue epoxy and glue the disk into place, other than that when you remove the carb you will see a second small disk, these are staked to place, just copy that one and make sure they are sealed as this missing will cause a very weak mixture and risk of overheating.
Steve Shaw Member No.2 Club founder and owner of Gasure.UK Trader Posts: 574
