I might be making trouble for my self with a diesel...

IT LIVES!!!

Fuel looked good, it had swirls in it like less than complete mixing, but no other signs of separation. I shook the jar and the swirls disappeared.

My soldering job sucked, I didn't even close all the corners...I ran it on a open syringe, but can't find the card reader for this computer right now...

I started with priming the intake only with the tank empty. Flipped dozens of time with no joy. Then I filled the tank (hahaha..it had holes. I think the flux sealed them for the vacuum test) Black funk started oozing out the INTAKE so I took quite a lot of fuel and overprimed the cylinder slowly. LOTS of black offal started pouring out the intake...

I flipped some more, then started fiddeling with the compression. Apparently the contra piston was gummed in since loosening the screw the piston would not go up after several flips, or was already all the way up. I tightened the compression and got a pop, flipped, flipped, flipped....tightened some more till I swear my OS40LA is softer to flip and it came barking to life! only to promptly quit since the fuel ran out onto my metal table and ground, and test board, and ...

Refueled the tank...yup holes, got my second fuel syringe and took the plunger out of one, and rubber banded it to the clamp holding the board to the table, put some fuel into the syringe, had to close the needle since the fuel was pouring straight out the intake.

I primed the cylinder slightly, probably flooded a little, and a few flips later popping of life, tightened compression and opened the needle a little, got it to run briefly, but flooded. Closed the needle, upped compression a little more, as soon as it barked I opened the needle and it caught and stayed running.

I noticed that the engine will run across a considerable compression range, and needle valve range. I rant it a few minutes rich and as low compression as it sounded stable and "4-stroking" I think. Black offal was still coming out of everywhere on the engine.

I tightened the compression and then adjusted the needle finding high RPM and the exhaust cleaned up some, it kicked into a strong "2-stroke" and almost blew my jar of fuel and rag away. I think this MK-17 ".09" engine has more to it than my Fox15!

I ran it leaned out briefly, refilled the fuel syringe without shutting down, then tried to find a nice running setting that was 2-stroke but would have a 4-stroke burp every now and again. I reduced the compression slightly from max rpm by ear, and it acted slightly rich when I messed with the needle (is this about right, reducing compression makes it act rich?)

I already repaired the fuel tank, but I think it is too big to fly. I like about 5 minute flights. I also smell like I took a bath in WD-40 after running the engine, and everything was bathed in oil and k1.

I think I will try adding a small amount of the cetane booster and see how it runs then. It seemed like too much compression to get it started, but I have nothing to compare to.

A Cox diesel is on the list. If I can find instructions for "soldering" aluminum I'll make a small tank diesel bee!

Phil

Woooh! You got it running! A slightly rich sound can be made by under compressing it. It will sound slightly off power. You also need to be careful running it rich and over-compressing it. This can be quite hard on it. It will be very smokey and use up quite a bit of fuel. I tune mine by turning it to peak if I can notice it and if not I turn it in till it misses out from being lean and then open it up until I hear power just drop off from richening.

If turning it over is like a 40 La then it may have too much compression. Some engines start under compressed. Others like over compressed. My 15 PAW starts at running setting. So do my Cox engines. The extreme compression may have been from a bit too much prime as well.

What do you think of the smell?

RR

Godsey3.0 wrote:
What do you think of the smell?

RR

I can get used to it. I felt like I bathed in WD-40 and couldn't wait to get in the shower yesterday though.

I thought I was over compressed, but that is where it wanted to run. I will add some cetane booster to the fuel and see if it will reduce compression.

Phil

What color is the oil? Pitch black, Kinda Dark, or Honey?

Near the end pretty light color. The stuff that initially came out - even before I got it to pop, was pitch black. Since everything was mixing with the funk I am not entirely sure the color of what was coming out.

Phil

Added the cetane booster today. Tried running it, but I think the 28F weather was against me. About 10 minutes in my fingers were numb, and a few minutes later I packed it up.

At a much lower compression setting, at least 1/2 turn less compression up to 2/3 turn less, I was getting life, but it wouldn't stay running. I couldn't tell if it was lean or rich, or the wind across the head was chilling the compression too much.

Phil

First runs are rich to expell any residual junk that you missed when you flushed out and inspected the inside of the engine for filings and flashing...you did check the inside didn't you?

The lower conrod bearing should smooth in during the first couple of minutes of running.

Once you get the engine running, take it up to peak power. After it has run for a minute or so and is up to normal operating temp, set it to peak again (the settings may change). This establishes your running position.

When you have it running at maximum, pull the fuel tubing to stop it and let it cool to room temperature. When it is cool, hook up the fuel and start it again. Let it run at max for about one minute and pull the fuel tubing again. Each heat up and cool down is considered a heat cycle. This will "break-in" your engine so that you get maximum performance and longest life. Other methods work also but I think this is fastest and most economical. About 10 heat cycles should do it. Heat cycles relieve the stresses imposed on the piston/cylinder during manufacture.

You do not break in a diesel by running it rich. Kerosene provides much more lubrication than methanol so it is not necessary.

George

The engine has been run and taken apart before. I did not take it open because I could not get all the screws out.

The slots are all messed up on all of the screws, it arrived that way. I am considering trying to get new screws and replace them.

The spring on the needle is weak. The threads on the needle appear worn. I think the brass gaskets/washers on the fuel pickup are worn and may be leaking air. I am sure this engine has several hours on it already.

Phil

http://modelenginenews.org/cardfile/mk17.html

This is interesting.

Phil

I tried the Diesel Kleen Cetane Booster. It seems to make it "pop" easier but maintaining a run was harder. I ended up with higher compression setting using a Tee Dee .049 with a #4 Cylinder compared to without the Diesel Kleen. Have you gotten a chance to try to run your MK 17 again yet? Which fuel mixture did you actually settle on? Equal parts or the 1/2a Mix? I intend to try to throttle a Cox diesel soon. Not the Sure-Start choke throttle. I will be trying an exhaust throttle. I think one of my RC Bee's with a KB crank should suit as a test bed. I need to make sure the crank is straight though. I bought this one in a Diesel Bomber during the time they were producing iffy cranks.

Riskin' Rolla

I went with the 1/2a mix. I ran it once without the diesel kleen, tried once with, I haven't had a day above 40F to play with it since. It is 4F outside right now. BRRR!

I did order a diesel bomber, not the RC version. If I change my mind on diesel then I put a glow head on and it's all better.

Phil

Today was 45F. Light rain at times.

I was able to run it again today. Is it normal to get it to start on prime with the needle closed, but not with the needle set?

I would get it to start on prime, then quickly open the needle 1 1/2 turns or so, and it would stay running.

Part of this problem might be since the tank is not at the same level as the engine with this test board setup. The tank ends up above the engine. I am still not very pleased with the needle valve spring, but figured out how to lock the banjo down so it seals a bit better.

I wanted to try my Diesel Bomber on diesel, but only ran it on glow for break in. I ran quite a bit of fuel through it, and it is running quite nicely on glow.

I am not convinced that diesel is the way I want to go, been fun so far but it is a lot more finicky than glow, to say the least.

Phil

I imagine the problem you are having is from fuel flowing into the engine. Try pinching the line (with pliers if necessary) and releasing when it starts. You will notice over time that diesels start to work easier and easier. Eventually they pose no problems.

Rolla