25 Hrs checks

[JAB]

Of Note:
Having just completed a 25 hr check on XD I had the misfortune to find 2 lower plugs siezed. The resultant work ended up with a top end overhall, requiring one new exhaust valve, valve damaged by helicoil breakage as bit passed out of exhaust. also two solid plug inserts were required these were fitted by Park Engineering of Malton. [This company are engine rebuild specialists]
After rebuild etc, and a full set of plugs [ouch! Barry Smith and his rel's] the flight test gave 950 fpm at gross auw - not seen that before so worth the effort.
However, I would have not needed to strip the heads if I had ensured that the plug threads were fully graphited on last fitment. Beware!
Lesson for all.

cheers

JAB

[Neil Spooner]

Hi JAB,

Not meaning to dampen the head rebuild job, but the 'plugs soak alot of heat away via the threads, it may be worth checking the plugs to make sure they are not running too hot. VW don't recommend helicoil/plug inserts, instead recommend the head welded and new threads machined. It may be worth moving to the next heat range cooler to prevent pre-ignition/detonation. If you have good mixture distribution and the plugs tend to look similar, compare your helicoil plug against the others for a colour comparison, it does no harm to run a cooler plug, but an overheating one can be a disaster.

Neil