wierd A4 question

[steven]

Laying A4 up for the winter as usual with raw water cooling intake from a bucket of antifreeze.
Running very smooth when . . . piston#4 (furthest aft) stops firing and just clacks.
Other 3 cylinders run fine without #4 firing.

Anyone encounter this ? Most likely reason and how to firgure out whats wrong? (spark plug wire, coil, blocked fuel jet, . . . )
Tried changing spark plug but that didn't work.

thanks

--Steve

 

[AlaskanPuffin]

The first thing I would do is pull the plug and turn it over and see if it will spark while grounded to the block. If you are getting spark then check the fuel system and intake and exhaust valve function. If no spark then it's probably the coil or plug wire or possible distributor issue. I hope that helps.

 

[steven]

thanks. that helpful. --steve

 

[tenders]

The valves in that cylinder have a tendency to stick. I run a few ounces of Marvel Mystery Oil in my fuel all season to keep ahead of that tendency and it’s worked for decades. This has been discussed at the Moyer Marine forums, which are an incredible source of A4 expertise.

 

[steven]

Thanks for te MMOtip. De-winterizing this weekend so I'll try it.
Just to be clear, dumb question, do you add the oil to the fuel tank ?

--Steve