Engine – ground run testing

As quite a lot was changed and updated the engine needs a careful planned set of ground run tests.

The first involves a short 1 min run and then removal of each rocker cover to check oil is indeed being pumped around each bore

It’s now been converted from Hydraulic lifter valves to solid lifter valves, the old way (hydraulic) meant that I didn’t have to do any valve checking as they self adjusted. Now I need to include regular movement and gap checking.

The checklist calls for around 10-15 timed and controlled runs .. starting with low revs ..up to 1200 and short runs just to get all oil distributed evenly.

It’s always a pain when you have emptied the oil cooler matrix – this is a new one so starts empty ! .. you need to allow for sufficient oil in the sump to fill that and perhaps any new filter that may have been added.

The dipstick on the Jabiru isn’t the greatest piece of metal known to man as, in the taildragger configuration, you don’t get an accurate reading, the dipstick being calibrated to read when the engine is in a flat orientation. The standard dipstick doesn’t reach the bottom of the sump !

Over and above the standard dip test every flight….I’ve got used to checking every so often by trestling the aircraft up to flying angle .. ie Straight and Level (you need to do this when occasionally checking the rigging and wing dihedral). Anyway, the standard dipstick mark is ignored and it’s ‘about’ 1/8” (in old money) covering the bottom tip of the stick.

At the last annual James, my engineer, grabbed the prop ..pulled the engine into its S&L position and put a stick down to check… the simplicity of this was quite obvious … vs ‘it should be about 1/8 on the bottom of the stick’ .. so I’ve created a new dipstick that goes directly to the bottom of the sump.

The remaining tests slowly take the revs up through 1800 block tests as they call them .. successive run ups and cool downs … giving you chance to check all is working.

Once you get to the 1800 tests the idea is to take it to 50’C oil temperature and THAT should open my TOCA – Thermostatic Oil Cooler Adaptor .. a neat slim block that fits between the engine and the oil filter effectively blocking (COLD) oil circulation until the engine reaches 50.

The subsequent runs take the revs up to 2400 which is where it will be difficult holding her on the brakes so the chocks will come in handy … pays to keep the elevator back in these power checks !

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