The more basic point is that if the installer doesn’t know about hydraulic tappets, he should stick to changing the oil, only. What about the cylinder bolt torque?
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Piston troubles
Talking to my FAA inspector and showing him a video of the G2 my pilot buddy took yesterday he says it cannot be cam related as the cam lobe actuating cylinder 5 is the same for cylinder 6 where we see no EGT issues. He continues to say it is the exhaust valve not closing. I just hope these few minute runs are not burning the valves of this new cylinder. This is going to turn out nasty as I am pretty sure the shop will charge hours for trouble shooting of a job not well done and will not concede to have screwed up.
My saga continues. Probes have been checked, all fine. Sparkplugs all fine. Induction leak performed. Dry tappet clearence all fine. Cam is ok. Cables and harnesses all fine. We are now back to square one. Since the original problem of the engine running rough on one mag they will investigate the ignition again. The magneto had been the first item to have been checked and found good. So we are now running out of ideas.
Rough engine on one mag, the original problem, is still there. Higher than normal EGT on the replaced cylinder is something which appeared with this new cylinder and was not present before. We have two issues to resolve and have on more clues.
Have you eliminated the possibility of the indicating instrument being faulty, by e.g. swapping two EGT probes across cylinders?
Yes, they have been swapped but the problem remains at cyl 5.
The magneto had been overhauled in August last year and sent back for review 2 months ago. No fault found yet the engine runs rough on one magneto.
When they found the old cyl 5 having no compression they thought that this was the problem for the rough running. The cyl got exchanged, the roughness on one mag is still there and now I have an additional issue being the high EGT on the new cyl. Papers were again checked so it seems I got the correct cyl assembly.
Any hint what else to chase is highly appreciated.
I think all that’s left is the ignition harness.
Placido, I think it’s high time that an engine specialist is looking at this before you end up AOG all summer.
I recommend Cermec.
placido wrote:
The cyl got exchanged, the roughness on one mag is still there and now I have an additional issue being the high EGT on the new cyl.
I suppose all cylinders are firing when running on the magneto on which the engine is rough? Do all EGTs increase when switching to the rough mag?
Do you know what kind of plugs you have? Have you thoroughly inspected the ceramic insulators on the plugs for cracks? Have you measured the plugs’ resistance? If you have the Champion plugs with the flat screwdriver slot in the bottom of the plug well you should consider replacing them all. See here for background. Many mechanics are still not aware of this, or do not believe it.
The right mag fires the top plugs on the right and bottom plugs on the left. The left mag fires the top plugs on the left and the bottom plugs on the right.This, together with an EGT that fails to rise during the mag check gives you the faulty plug. Although when I say plug, it could be plug or HT lead.
