A new data point: oil burn is now down to 1qt in 4hrs.
So it looks like running the engine at a high power did the job.
Obviously I need to collect more data, with normal power flights (60-65%) to make sure this is not a fluke which happens only at higher power settings, and then some short FL100-120 flights to verify it.
Probably it could do with one more 1hr flight at 100% power.
BTW Fedex want GBP 1700 for one-way shipping to Oklahoma, which is about 1/2 of what I was quoted in 2008. DHL is a lot less still but my business has a discount scheme with them. This is really very good compared to air freight which is a very low reliability service if you are looking at door to door.
Peter wrote:
BTW Fedex want GBP 1700 for one-way shipping to Oklahoma, which is about 1/2 of what I was quoted in 2008. DHL is a lot less still but my business has a discount scheme with them. This is really very good compared to air freight which is a very low reliability service if you are looking at door to door.
For an engine ? Ifso, that’s outrageously expensive.
I just air freighted a prop from Chicago to Paris for just $350 . Typical quotes for an engine run about $600 – $750 . Mind you that’s door to airport so add in a couple hundred if you need door 2 door.
I never use FedEx they are THE MOST expensive .
Peter wrote:
The feeling I get is that oil burn correlates with altitude, or (equivalent) power output.
Lycoming says: “There are some other considerations of low power cruise operation. Low manifold pressures, below an arbitrary point of perhaps 18 inches for continuous cruise, may cause excessive oil usage, and oil buildup in the valve guides which could lead to sticking valves.” 18 inch or below is 12000 feet and higher.
(local copy – added in case the source gets moved}
Lucius – Thanks for posting that source – I have all the Lycoming Flyer articles but in print (non-searchable) media. Having the re-prints on-line is a great resource !
Many thanks for finding that, Lucius.
Interesting they say nothing about how to fix it. They also say the valves get bunged up, which is certainly not the case with me. I was losing oil due to crankcase compression i.e. leaking rings.
The flyer also incidentally talks about icing in injected engines but they just mention the case of the air filter covered in ice, not icing in the servo
Peter wrote:
They also say the valves get bunged up, which is certainly not the case with me. I was losing oil due to crankcase compression i.e. leaking rings.
How did you establish that? From what you’ve written so far, I don’t think you actually have.
Well, true, short of opening up the engine totally one can’t be sure, but with a lot of oil coming out of the breather, none out of the exhaust, and compression historically always 78-79/80, what else could it be?
Leaking valves probably can’t be cured by flying, too.
The other thing is that I have never had this before, at least not noticeably, in 13 years, which must have sort sort of significance. The answer is probably in that every long (high altitude, often) trip was interspersed with local flights at normal power.
The logic doesn’t work out.
If it’s crankcase pressurization, then that means leaking piston rings — the upper two, not the lower oil control ring that has nothing to do with sealing the combustion chamber. So the stuck oil control ring and crankcase pressurization do not go together.
Oil being burnt in the combustion chamber does not necessarily mean you should expect an oily exhaust. It depends on the quantity. You do have extremely oily plugs so you definitely have a problem with oil getting into your combustion chamber. Even if you’ve had that for a long time, it’s not good.
You definitely could suffer from oil passing through the valve guides. Have you removed the rocker covers and inspected for sludge and light colored gas marks? Also you should make sure you follow the Lycoming 400h valve check SB, that’s a very important one. Sticky valves take a long time to become noticeable. You could very well be losing that oil through the valve guides.
I think there’s still work to be done to figure out this engine problem.
You do have extremely oily plugs
I did have them on the occassion where I didn’t run the engine for a bit before shutdown. See the later photos. They are OK – or at least as normal.
I will have another data point on the oil burn after today’s flight. The last one was back in line with historical usage.
BTW I had a GBP 1700 (each way) quote from Fedex which is high but is 2/3 of the one I had in 2008. And one from DHL which is incredibly lower than that and almost the same as crappy air freight, but we do have a discount package with them. This is 1mx x 1.2m x 1m high, 200kg, on a pallet. The pallet and a container (with the rubber stamps required by the USA) is GBP 130. The 2-pack foam spray kit to fill the void is GBP 250. So the costs of shipping to a decent firm in the USA are pretty low, especially as the cost of the job itself will be a good few k lower than in Europe. The only way to save on the shipping containers is to be able to put the engine in the back of a van, lying on a tyre (the usual way here in the UK) but there are zero reputable shops within driving range of me.
Peter wrote:
The answer is probably in that every long (high altitude, often) trip was interspersed with local flights at normal power.
+1
