Peter wrote:
After maybe 10hrs, one can run around at say FL090/100, but if you get any bad wx and have to climb above it, you run the risk of glazing the cylinder(s) and then IME it can take 100-200hrs of lots of oil burnt before the glaze comes off. We have some previous threads here on how to remove it with a nasty solvent but that also damages any engine seals so you have to give the engine a good rinse if you do that, to make sure no solvent reaches (especially) the front crankshaft seal.
The way modern machined engines come off the bench, you might find that this whole bedding in thing is vastly exaggerated in particular when it comes to the oil burn. If you can, yes, run it in at full power for 30-40 hours at 3000ft on mineral oil. My recent experience with the lycosaurus shows that oil burn was down to less than 1litre per 7 hours after 7 hours. I then burned a little less than a liter at 8000ft 22inch/25 rpm for 10h35 across the Atlantic. That’s on a new engine… (basically everything from the firewall forward new)
LFHNflightstudent wrote:
If you can, yes, run it in at full power for 30-40 hours at 3000ft on mineral oil.
Why? That’s not at all what the engine manufacturer recommends. The Lycoming recommendation is along the lines of full power for an hour or two, then alternatively full power and 65% for another hour or two, then not less than 65% until 50 hours when you change to regular oil.
But with a normally aspirated engine, you can’t reach 65% above about 12000’.
It is indeed possible to get a stabilised oil burn after just 7hrs.
I will have to see.
you can’t reach 65% above about 12000
I would have to look it up but last time I was doing this stuff it had to be “best power” i.e. burning some 20-30% more fuel per mile. So, yeah, you can fly at FL120 but still wasting a huge amount of money, and with a much reduced range.
Repaired cylinder with a new exhaust valve. The old exhaust valve looked ok when cleaned up, and apparently most people go for that, but I preferred to not have a valve with a “special customised heat treatment” 
Total bill 700 quid.
Labour 200, parts 340, plus VAT etc.
The valve guide apparently had only some carbon in it and a reamer took it out.
I read some more about the “old rope trick” and one of the gotchas is that you can end up with grinding paste in the cylinder. Obviously, if you are stuck somewhere in Egypt then you have to do that…
I m surprised there isn’t a tool which can fit through the spark plug hole and which can pick up a valve by its stem.
The cam stuff can be inspected to some extent and looked entirely clean
Valve stem varies from 0.4922" (most wear) to 0.4938" (where not worn). On a quick look for the limits
it looks outside new limits (the 1st numbers) but not outside service limits (the 2nd number). However I am not sure if the service limits apply anyway, per the note. Does the IO540-C4 use nimonic valves? They are certainly not inconel.
Excellent news and a very quick turnaround.
If i remember correctly you are going for a rehone new rings and then need to run-in now?
Yes; new rings, a re-hone, and ~50hrs on straight-80 oil. Doing it today.
I am tempted to use W80+camguard from then on, avoiding 15W50 which (on anecdotal evidence) may produce more carbon buildup. The engine is temperature controlled anyway so AFAICT the multigrade is relevant only to getting it started.
I went to a show once.
I asked the shell guys what Oil to use on a IO360.
He asked how well I want to look after it.
I was surprised.
He said if you can be arsed w80 and w100 interchanged between seasons.
If you can’t get everyone onboard with that (shared aircraft) 15/50.
Oh I thought, everyone else tells me 15/50 but You’re the expert.
Later that day I walked past the Lycoming stand.
I asked the same question. Hang on a minute sonny, our expert will be along in a minute.
Two guys from lycoming came a long and were very knowledgeable and friendly.
His/their first reaction was, well, how well do you want to look after it? Then followed the same answer.
They are probably all mates, and talk the same topics, but as industry ‘Experts’ from the two big players, I could hardly disagree.
Could well be right.
The cylinder is back on and the engine runs perfectly. EGT on #2 is also perfect and in line with the rest, all the way down to idle.
There was a significant blow-by into the #2 rocker cover. However some is not that unusual at say 400hrs and #4 shows a little bit also.
It is an interesting learning experience, how the oil flows through the hydraulic tappet, via the pushrod, into the rocker arm, through a hole in that it then sprays onto the stem of the exhaust valve (the inlet valve doesn’t get this spray). Any blockage in that long path, and your valve will eventually seize up.
And there is no way to check that il is actually coming out into the pushrod. You can check the orifices are all clear, sure.
Curiously the #2 dry tappet clearance was nearly the 0.080" limit, so we swapped the two pushrods over. Whether this is significant I doubt, unless it happened very recently (an oil blockage causing the pushrod to wear shorter by about 0.050") because my oil analysis has been perfect, right up to before the last 2 flights which were 2.5hrs total. Can one wear 0.050" off the pushrod in 2.5hrs?
I don’t think your pushrod wore 0.050 inches… if it did that over the course of the engine TBO I think it would unacceptable.
