Diesel engine, could use some help.

[Jeffrey Cottrell 2]

Hi Guys
Little outside my comfort zone, so I could use some help.
Bought a model at a swap meet recently. A Slicker, one of the prettiest designs from that era, imho. Came complete and ready to go, including a small diesel engine.
So, first question.
I am told it's an AM 1cc. No labels or markings on it, so could anyone confirm?
Pics should be hearabouts.
Runs well when I can get it started, but seems to start only when it wants to. Sometimes doesn't show any signs of life, even when I hit it with a starter, which I'm reluctant to do with such a small motor.
So, looking round for possible causes.
It is fitted with a wooden prop. 8" dia but pitch not known. The prop is feather light. Seem to remember they perform better with a heavier prop, something about 'flywheel' effect. Would I be better with heavier one?
It uses neoprene tubing, which has gone stiff with age, so my fuel bottle doesn't fit very well. Can't say for sure whether the tank is full.
Finally, what might be the biggest issue.
Pulled the tank out, and it looks like a control line tank, with one pipe heading down and the other up.
The upward pipe has broken loose (solder joint failed) so I need to replace it anyway.
Anybody know where I can get a free flight tank for diesel fuel?
Must admit I could pull the motor and go electric, but it has such charm as is I would like to keep it and make starting more reliable.
Any thoughts?
Jeff

[Alan Gorham_]

It's an AE engine, not an AM. Both designed by Dennis Allen but the AE designs were made in the early 1990s.

[Alan Gorham_]

I found with mine that it was a ready starter if you give a tiny prime (2 or 3 drops only) against the side of the piston with the exhaust ports closed. I'd make my own tank from sheet tinplate and brass tube as sold by K&S. 

[J D 8]

 I have an AE 1.5 and  agree with the above, couple of drops in exhaust will get it going. Tank may well be your problem to keeping it going. A heavy prop can also help when hand flicking. 

 

[Jeffrey Cottrell 2]

Hi Alan, and thanks.
Think you've broken the world record for replying to my questions. Almost before I'd finished typing.
Nice one.
Thanks for the tip on priming. I was squirting fuel down the carb, so maybe over-priming was an issue.
Anyway, next step is to get it on a test stand so I can have a proper play.
Did a quick google search on AE engines. seems there is no external difference with the 0.5 1.0 and 1.5. However one I read did suggest that with the 1.5, you could see the end of the thread for the rear head bolt above the backplate. I could see this sign on mine, which maybe suggests I have the 1.5 one.
Anyway, suggested prop sizes for the 1.0 as 7 x 4, and the 1.5 as 8 x 4, so maybe a different prop is on the cards.
Finally I have neither the facilities or the skill to make my own tanks, but Den's Model Supplies seems to have quite a range, so I'll give them a call, see what they say.
Jeff

[Jeffrey Cottrell 2]

Hi J D 8

Interesting. I have read that on the 1.5 you can see the bottom of the thread for the rear head bolt at the top of the backplate. I can see this on mine, which would suggest mine is a 1.5.

I did mention that the upper pipe on mine had broken away, and since it looked more like a c/l tank than f/f certainly is not helping. Anyway, going to make some phone calls tomorrow, see what I can find.

With such a small motor, I'm reluctant to use a starter on mine, but do you use one, and any after effects?

Finally, what size prop do you use?

thanks Jeff

 

[Engine Doctor]

Definitely no starter motors or you will wreck the engine ! Prop size isn't critical with a diesel the 1.5 could happily run on a 7x4 up to an 8x6 even a 9x4 depending on what you are flying. 

Tin tanks really are simple to make. Use tin from a thinners can or chocolate tin and remove any printing on the outside. You could even make one fron thin brass sheet available from LMS. Make cardboard template first and leave a 2 to 3mm overlap on one of the sections to allow for the solder to form a Web in the join. Brass tube from any LMS for the tubes. A soldering iron of 75w would be ideal and ordinary fluxed solder is perfect for the job . If you do have a go rinse the tank out with cellulose thinner when finished to remove any flux as it can block the tubes .

The beauty of making your own tank is that virtually any shape can be made to fit into very awkward places in the airframe. 

If interested search for  forum.medwaymfc.org.uk and then click on Builders forum then models of Other Designers and make and then Frog 45 on page 2 . 

There is a detailed description of building a tank into a small space to get the biggest capacity. 

[J D 8]

Hi Jeff, I know mine is a 1.5 as I still have the paperwork that came with it when purchased in early 90's. It spent some time in a c/l FW 190.  The head/cylinder bolts go all the way down to the crankcase but I suspect this is the same for all sizes.   Height of motor from bottom of crankcase to top of head [ not including comp screw ] is 5.5 cm's. This may help but I have no others for comparison. 

   Mine ran well on an 8x4. master with a spinner.  A good flick with a chicken stick to start. Cheers, John.

[Jeffrey Cottrell 2]

Hi Guys, thanks
ED
Couldn't agree more about using a starter on small engines. In fact I don't even like using one on my larger engines.
Much as I would like to make my own tank, I am up to my neck in other projects.
So many models, so little time!
Anyway came across a company who can supply ready made, so I have ordered a 10cc one from them. Should be here in a couple of days, we'll see.

JD8
Apparently the external size is the same for 0.5, 1.0 and 1.5. it's only a guess that mine is 1.5, but it doesn't really matter anyway. Whichever it is has enough power to give a vintage like flight performance, so what I really need is to make it easier to live with.
To that end I have the engine on a test stand, and a couple of APC props coming to test with.
I noticed the old tank had a broken off upper feed tube. When I pulled that out it turned out to be a c/l stunt type wedge tank. That can't have been helping. Anyway, hope the new bits will make it perform better.
Work in progress
Jeff

[Jeffrey Cottrell 2]

Hi Guys

Success, and thanks for your help.

New tank, 8 x 4 APC prop,and new tubing. Had it on the test stand, hand start and absolutely screaming on that prop.

Little jewel.

Took a few minutes to find the comp setting, but after that, all good.

Couple of thoughts.

Think I might have overestimated the tank size. Old one that came out gave me 2 minutes flat out, which was enough to get to a good height, but no idea what size it was. Guess said 10cc, which is what I ordered, but test run seemed to go on far longer that 2 mins.

Ho hum, test flight will decide.

Also, I understand I can't use silicon tubing with diesel fuel, hence can't use a clunk tank, but could I use it just for the fill tubes? Got some Tygon for tank to engine, but it's incredibly stiff and a problem with the half buried fuel tank.

Your thoughts?

Jeff

[Paul De Tourtoulon]

Is this for a glider or free flight model, if so a home made tin tank like we use in control line, you don't need a clunk.

[J D 8]

   Silicon tube will do for the fill/vent pipes, it will go gooey in time but we are talking months/a year.

Use a syringe to fill tank with say 5cc and test the run time. They do go like stink when tuned in.

[Dickw]

3 hours ago, Jeffrey Cottrell 2 said:

.......................

Also, I understand I can't use silicon tubing with diesel fuel, hence can't use a clunk tank, but could I use it just for the fill tubes? Got some Tygon for tank to engine, but it's incredibly stiff and a problem with the half buried fuel tank.

Your thoughts?

Jeff

Long time ago, but I think it was neoprene tubing we used for diesels as it is oil resistant.

Looked like this stuff

https://www.modelshopleeds.co.uk/catalog/product_info.php?keywords=fuel tube&sort=1a&products_id=56704

 

Dick

[Peter Christy]

I got some thin-wall tygon stuff from somewhere which is reasonably flexible, and works fine for tank to carb pipe on my c/l models.

 

I have used clunk tanks with diesels many years ago. From memory, we used synthetic rubber tubing. It was thin walled, black (not transparent) and very flexible. Never had a problem with it, but can't remember where I got it. Probably from the local model shop - which, of course, no longer exists!

 

Perhaps PAW or Jon from Laser Engines (they've made diesels in the past) may be able to advise a source.

 

--

Pete

 

[Paul De Tourtoulon]

Wasn't it Butyl Rubber Tubing

[Engine Doctor]

23 minutes ago, Peter Christy said:

I got some thin-wall tygon stuff from somewhere which is reasonably flexible, and works fine for tank to carb pipe on my c/l models.

 

I have used clunk tanks with diesels many years ago. From memory, we used synthetic rubber tubing. It was thin walled, black (not transparent) and very flexible. Never had a problem with it, but can't remember where I got it. Probably from the local model shop - which, of course, no longer 

 

--

Pete

 

It's called Nitrile tubing . Paul suggested Butyl rubber tubing You should be able to find it on the Internet. You can get thin walled tygon from Dens Models. He's on the Isle of wight does lots of FF and CL  stuff.

Edited September 2, 2022 by Engine Doctor

[Martin Harris - Moderator]

I bought some of this for a smoke system - I think it’s suitable for model diesel fuel and quite flexible. 
 

https://www.ebay.co.uk/itm/130740225601?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=AYb5tW8MRea&sssrc=2349624&ssuid=I-OuwxIhQjC&var=&widget_ver=artemis&media=COPY

[Jeffrey Cottrell 2]

Hi Guys

Little bit of a find.

Went to a model show today. On the SLEC stand I found they do a conversion kit for a clunk tank for petrol or diesel. Rubber bung not really of use, but a length of the thinnest, most flexible Tygon tubing I have ever come across. Perfect for my needs, and only £2.

Game on!

Jeff