Scudrunners

Slick Goodlin wrote: Thu Jun 27, 2024 4:11 pm
You should have seen my daily driver a couple summers back…

Was it a model T? I remember you talking about owning one.

David MacRay wrote: Sat Jun 29, 2024 12:55 am

Slick Goodlin wrote: Thu Jun 27, 2024 4:11 pm
You should have seen my daily driver a couple summers back…

Was it a model T? I remember you talking about owning one.

‘Twas. I still have it, it’s just been lightly exploded for a couple years now. Broke from age, taken apart and left that way thanks to my own poor planning.

I understand. I had a dragging brake on my Eldorado. Got distracted last year doing things besides fixing it. Drove it today. Poor thing needs some care.

Maybe most importantly this thing’s flown more in the last month than it did all of last year. …but still less than it flew on most single days in 1941!

I like the knife edge flight

I’m itching to get flying again soon, hopefully later on this week. Then after maybe five hours of this flush I’m going to do something that seems like it should be so illegal: drain the oil, filter it outside the plane, then put it back in.

Well, if you don't have a filter inside the engine, why not use one outside the engine?

I might recommend a filter rated for a low fewer microns than a normal oil filter. A
better one, which will remove more particles. You're not in a hurry, so the flow rate
of the filter doesn't matter. You're doing it offline. You could even filter it a few times
and see if that helps.

A major problem with cleaning old oil and re-using it, is that you don't replace the destroyed
VI's ... but that's not a problem for you. You're running straight grade, not multi-grade
with the plastic VI's. You don't even run dispersant (W) oil. If I were you, I probably would.

I might recommend some AvBlend for your crankcase, if you want to clean the inside
of your engine. It's a pretty good solvent, and it's even legal. If you're experimental there
are lots of other options. I have had best results with solvents like AvBlend when I
put fresh dispersant oil (eg W100) in the crankcase with it.

A peek at the pressure screen might be interesting. Odds are the solvent will dissolve
the carbon deposits but .... if you find debris in it, take your time and try to dissolve it
in some mineral spirits, rolling it inbetween your fingers. If it vanishes, you have nothing
to worry about.

If your pressure screen looks like this, your camshaft is gone:


Do you have a suction screen? Generally it's pretty coarse compared to the pressure
screen (which is pretty fine) and if you find stuff in the oil suction screen you can often
read part numbers on it. Probably not your problem.

I wish I didn't know all this stuff. Been poking at aircraft piston engines for over half
a century now. They're actually pretty simple, and if you keep them clean, run ok.

Oddly most people are not interested in operating engines to keep them clean inside,
and then they have problems.

I’d be surprised if the little A40 has a screen on it anywhere apart from the coalescing screen in the filler/breather pipe and even that looks aftermarket. The manuals aren’t much help there either but maybe I’ll dig around in one of the spare engine cores in the parts room to see what’s up.

Speaking of reading part numbers in your oil chunks, I finally got around to doing the annual on the Champ the other day (AMEs and/or weenies with Transport on speed dial can settle down, it’s a homebuilt) and I nearly had a heart attack cleaning out the little cup in the oil drain plug. I actually did end up washing the bits found in there to make sure they weren’t metal and nope, near as I can tell they were all carbon.

I think I have some case washes being added to my summer schedule…

There's probably something wrong with me, but I like solvents. I really like them.

I like putting solvents on the outside of my engine (mineral spirits in a spray bottle)
and scrubbing it with a gentle brush and wiping it off so I can find the oil leaks.

I like solvents in my oil. Avblend is the most expensive FAA-approved ether you will
ever purchase and it does a marvellous job of dissolving carbon and varnish.

I like solvents in my fuel. Clearly not certified aircraft engines, but everything else.
A splash of Seafoam (the most gentle solvent around) in the fuel system keeps the
engine running smooth.

Funny. The above proves there is yin and yang in the universe. I have sister in Toronto
(she is a totalitarian communist, of course) who led the campaign to get rid of lawn
treatments.

On the other hand, I have never met a solvent I didn't like. Water, gasoline, mineral
spirits, acetone, toluene, MEK, laquer thinner, hydroflouric acid you name it. I know
and cherish them all. I like stuff clean. It's a horrible character flaw.