Air-cooled engine knocking

[mariner]

Hi all

Appreciate any advice anyone can give me - have a 2 ltr air-cooled and the engine is knocking/juddering badly when idling in traffic, so much so you can feel it vibrating throughout the whole van. Driving ok, judders a little sometimes when accelerating but nothing too bad and starts well. Anything obvious I should be looking at first?

Thanks for any help.

[ethelred the ready]

Engine mounts perhaps? Maybe with some tinware knocking also as the engine rocks.

[mariner]

Thanks for the suggestion. Unfortunately they are sound and solid - would have been a cheapish fix!

It really sounds like the engine is struggling to turn itself over and wants to cut out, although it doesn't. As a result we get the judderring of the whole engine. Like I say, no noticeable issues when driving. Had the dizzy cap, rotor arm, plugs and oil filter done just before we put it in storage for the winter as she wasn't driving too well then. Only been out a week or two!

[ethelred the ready]

Try fuel iessues next then, petrol filter, carb maybe the idle jet if it drives ok but idles poorly. I assume oil pressure is ok and it doesn't sound like the big ends knocking, just engine judder.

[marlinowner]

Could be sucking air into the inlet manifold making the mixture weak at idle, try spraying some wd40 around the carb bases, vacuum and servo pipework etc, if the revs pick up then you have found a problem.

[mariner]

Cheers guys appreciate the replies. Was thinking carb/fuel issue myself after a chat with the father in law but no mechanic so will have to contact the garage! is there anything I can buy to put in with the fuel that might clean through the carbs or fuel lines or is that just not even worth bothering with that?

[BOXY]

we put it in storage for the winter as she wasn't driving too well then. Only been out a week or two!

Did you drain the petrol? If not fill up with fresh fuel and try to clock up enough miles to empty the tank again.