DIESEL ENGINE

[PETER JENNISON]

CAN ANYONE POINT ME TO SOME INFO ON DEISELS?HAVE NEVER RAN ONE BEFORE,DONT KNOW HOW TO SET COMPRESION OR NEEDLE PROPRLY!CAN GET THE THING RUNNING,BUT NOT WITH ANY SORT OF TICK OVER,DONT SEEM ABLE TO CATCH THE NEEDLE IN TIME TO ADJUST IT!ANY HELP OR ADVICE WARMLY WELCOME.

[John Van Buuren]

The PAW instructions may have something for you:

http://www.eifflaender.com/instruct.htm

[PETER JENNISON]

THANKS FOR REPLY,BUT I HAVE ALREADY READ THAT ONE.WILL TRY AGAIN!IT MUST BE A BLACK ART!

[Mike Rolls]

Peter
Are you running a throttled diesel? If so, as with glow motors, you need to sort out the top end first. Easiest way to do this with any strange motor is to ignore the fact that it has a throttle - leave it wide open. Close the main needle completely. With the motor dry and the comression screw backed off carefully turn the prop over by hand. As you do so, gradually increse the compression until you feel resistance; back the compression screw off a complete turn.
Assuming the motor has a silencer you then need to prime through the intake - still with the main needle closed. To do this in a repeatable manner, turn the prop so that you see through the intake that the shaft has closed it off and dribble some fuel into the intake. Difficult to say how much you will need because it will depend on the size of the motor and the layout of the intake but for a starting point try half filling the intake. Turn the prop over (DON'T flick it - you will get the fuel spat back at you) to distribute the fuel through the engine. This will need the prop to be turned over a few times - set yourself a number of turns and always stick to it. I normally use six turns of th eprop with an unknown engine.
Now start flicking (DON'T, whatever you do, use an electric starter). As you do so gradually increase compression until the motor fires and runs off the prime. Don't try to open the needle vals - just let it run off the prime. If it doesn't fire at all even when the cmpression is reaching the 'resistance' point, back it off again and re-prime, this time with a bit more fuel.
Once you have got the motor to run off the prime, prime again, this time with the needle one complete turn open. As it runs on the prime it will either die - whihc means that the needle isn't yet open far enough - or it will run rich - but being lean at this point is most likely. Simply repeat until the motor will continue running.
Where many folk new to diesels run into problems is in trying to get the balance between the compression and needle setting right. Until you have run one for a while this can be a bit of a puzzle. The things to look for are:
1. Reduce compression until the motor starts to misfire - this will teach you what an under-compressed motor sounds like.
2. If the motor starts to labour it will be either over-compressed, too rich, or both. Black exhaust residue is a sign of over-compression, as is the motor picking up revs as you reduce compression. Too rich will give a very oily exhaust.

Once the top end is sorted, the bottom end is just like adjusting a glow.

HTH

Mike

[Allan Jordan]

Hi. Mike, Good answer for Peter there, if he follows your advice he should have no more trouble. My guess is that you are of the old school of modelling,am I right? Regards, Allan J.. TTFN

[Mike Rolls]

Alan
not much old as ancient! First flew a model in 1947, first owned a diesel in 1951. Now flew electric exclusively, but can still start a motor (usually) when some have given up on it!
Regards
Mike

[PETER JENNISON]

MANY THANKS!ENGINE IS ONLY .75,COMPRESION SCREW AND NEEDLE VALVE ONLY.HAVE MANAGED TO GET IT RUNNING NOW,JUST NEED TO HONE THE FINE TWEAKING!I NOW KNOW I HAVE IT OVER COMPRESSED AS I HAVE LOVELLY BLACK RESIDUE ALL OVER MY WORKMATE!HAVE ALSO LEARNED NOT TO PUT TEMP FUEL TANK ABOVE THE HEIGHT OF THE ENGINE!!!MASSES OF HELP GUYS,THANKS AGAIN,I WILL GET THERE!

[Mike Rolls]

Well done, Peter - welcome to the ranks of the ether heads! What is th emotor? Mills? DC Merlin?
Regards
Mike

[Allan Jordan]

Hi. Pete, Glad youv'e started to get to grips with a diesel.They really are lovely engines to play with! They are more economical than glow engines plus size for size they will swing bigger props! Just love the smell too. Regards Allan J... TTFN

[Allan Jordan]

Hi, Mike when I read your pearls of wisdom
to Pete I just knew that you were about the same vintage as me. I started about 1948/9
with Frog 100.I used to build during the week and destroy them at the weekend. Oh happy days!! Regards Allan J ..TTFN

[PETER JENNISON]

HI GUYS ITS A DC,WHICH RIGHT NOW IS DRIVING ME MAD!CAN GET IT TO RUN FOR 5>10 SECONDS AT A GOOD SPEED THEN IT DIES.STARTS AGAIN STRAIGHT AWAY THOUGH,?HAVE TRAWLED FORUMS FOR BOOKS AND INFO,VERY FRUSTRATING RIGHT NOW.HAVE GOT A MILLS COMING FROM BARTON,THEY HAVE BEEN GREAT!HOPING THAT RUNS SWEETER.YES THE SMELL IS GREAT!ITS BEEN A REAL LEARNING CURVE,JUST HOPE THE MODEL STANDS UP TO MORE THAN ONE FLIGHT.GOT TO LAST UNTILL THE BIG MASS LAUNCH!

[John Van Buuren]

Hi Peter,

Does the motor sound like it is labouring, in which case it is probably over-compressed? If it is burping it will be under-compressed.

Does it die quickly, or miss a bit then die? If it comes to a dead stop it's probably rich, if it misses and runs down to a stop it is probably lean.

If it runs for a few seconds on the prime then stops it may not be passing fuel thru the needle valve. Leave the needle set to where it should be (close as possible) and try squirting some fuel through the inlet with a squirt bottle.

Another common problem is that the hole in the spray bar needs to be pointing directly down into the engine, unless there are two holes like PAWs. These are bored offset and they both need to be pointing down as much as possible. Sorry, but I can't remember what a DC spray bar looks like.

The only other conditions that sound like matching your engines symptoms are that it is quite new and needs running in.

Welcome to the oily-hand brigade. :-)

[Patmac]

Hi Peter, do you have the DC engine instructions ?
If not I can scan you a copy.

Cheers,
Pat

[PETER JENNISON]

Patmac,that would be really usefull thank you.John,it just runs down as if it has run out of fuel?slows down,no missing or burbling.open the needle a1/4 of a turn and it sprays black oily fuel out of the exhaust ports.afraid no one at our club knows about deisels!a sign of the times?the supper highway of information is not very helpfull right now either,so thank you for taking the time to help out.

[Patmac]

Peter, I've scanned the DC instructions as 4 gif files & inserted them into a MS Word doc. The file is 3.2MB. I've also scanned the text of an article on operating diesels from a book using OCR software into another Word doc. This file is without any illustrations but only 41KB.
Because of the size of the instructions file it'll need a broadband connection.
Can you open MS Word OK & do you have broadband ?
I'll need your email address also. There doesn't seem to be any private message facility on this forum so you will either have to temporarily change your profile to accept emails or you culd contact me via the PM facility of either http://www.bmfa.org/forums/ or http://www.rcmf.co.uk/4um/

I'm a member of both these sites with the same username.

HTH,
Pat.

[PETER JENNISON]

thank you,sorry for reply delay but for some reason auto inform for this thread does not seem to be working?was not aware of your posting.have registered with bmfa,thanks for the info.ran my mills tonight ,its a gem!dc still not running,sure its needle related,but want some info before i strip it.

[Patmac]

I've sent you an email.

Pat.

[John Van Buuren]

Running down like it's out of fuel, plus black exhaust, sounds over compressed. I would try turning the compression back a quarter turn just after it starts. Generally you can 'balance' the compression screw between under-compressed, which is an intermittent burping run, and over-compressed which sounds laboured and it would tend to run down like yours does. You want to aim for only just smoother than the over-compressed run.

I would leave the needle for the moment and concentrate on the comp screw first. Diesels aren't usually as sensitive to needle setting as glow engines. As Mike Rolls says above, try and get it to run on a prime while getting the comp. right, then open the needle valve.

[PETER JENNISON]

i now know why the dc was playing up.bent conrod!stripped it last night,after i realised it was not a fuel or compression issue.all your posts,and the fact the mills was so easy to set up led me to think it was more involved,so i decided to strip it.crank does seem ok,gudgeon pin seems very slack!?think it may be time to send it to Bartons,thanks again.