Why won't my tee 049 run properly

mad monky wrote:Well I'm stuck here.

My cox tee 049 is hard to start and tune compared to my baby bee.
When it runs it runs well but after 20 seconds of running smoothly it just stops and i can't start it again after 30 mins of messing with it.

The setup is a 5x3  prop and fuel is approximately 7.5% synthetic oil 12.5.% castor oil and 15% nitro. I got this mix by mixing together other comical fuels. You might say don't tamper with fuels but in my baby bee and flyer engine it's great it starts first few flicks and runs well and have had no engine trouble so far.

Some things to check:
Is your fuel tank as close as possible to the engine and level with the NV? Is your needle valve sealed with a bit of fuel tube in place of the clicker spring? If not, it could be sucking air through the threads or rotating due to vibrations. Is there a hairline crack in the venturi housing? Are the three sprinkler holes in the venturi clear? Does it feel like it has good compression when cold? How about when hot? With your low nitro, you may want to remove any extra head gaskets and just use one. Also use fine, 800 grit sandpaper on a glass pane and deck the surface of the head to ensure it's sealing when it heats up. Have you tried another glow plug? Maybe the platinum is gone or contaminated and won't react with the methanol to stay lit. Try one of the Bee heads with one gasket. Is the ball socket tight? If it was badly loose it might be worth a look. Check the seal of the backplate and deck the back of the crankcase like you did with the head.

If you don't get it worked out, post back and we'll keep trying.
Rusty

If it stops running after its hot it could be a caster varnished cylinder, piston. In the high humidity down here its a problem for me.

It has good compression at all temperatures,there is no play in the ball socket,no cracks ,glow plug is fine.

It could do with a cleaning so i will do that.

I have optifuel 25 car fuel is it ok to use it for a short run to see if its nitro content. It's synthetic.

I will keep trying different things and if i have no look i will ask other things that i can try.

mad monky wrote:It has good compression at all temperatures,there is no play in the ball socket,no cracks ,glow plug is fine.

It could do with a cleaning so i will do that.

I have optifuel 25 car fuel is it ok to use it for a short run to see if its nitro content. It's synthetic.

I will keep trying different things and if i have no look i will ask other things that i can try.

It's okay for a really short test, but it will overheat, so don't run a whole tank at once. But if it starts easily and sings, it would be nice to know. You can go to the dollar store or grocery store in the medicine section and get some laxative castor oil. It's too gummy for full scale use, but perfectly fine to spike a small amount of fuel with. After mixing, shake it well and shake it again. It sometimes won't mix easily. Good luck,
Rusty

Ok, so i have my tee dees cylinder off and am looking into the crank case and cylinder and at the piston, what am I looking for that's not dirt because i have found a small amount of fluff. I can't see any damage to moving parts and there is little play in parts.

Oh I forgot to ask,
Can a tee dee crank take the strain of a diesel head because i love diesels and fancy a miniature diesel.

The crank is strong enough

Looks like an engine made by Ronald Valentine?
He would certainly know enough to make a new and stronger crank...

I haven't pushed my diesel conversion very hard, but haven't broken any cranks yet. The trick to the diesel conversions is to use good fuel, a large prop (aim for around 10000rpm), and a proper diesel conversion head (not the crappy teflon ones...)

Here is a cox 05RC with a RJL head;

Thanks for the vid.
Would it be a stupid thing to do to dieselise it.

Ok I cleaned the cylinder and piston of tarnish by rubing it with scawring pads pads and now its Cleen and feels smoother but that could be cycalogical. As i was putting it together again i knowtist there are 3 shims under the cylinder head, how many sould there be.

The RJL and the Norvel diesel heads are very good.

The Valentine conversion is in a different league and way better. The inlet manifold is reduced in size to suit diesel fuel.

I haven't got on at all well with the cheaper conversions - they work but do not seem to last long and keep a good seal.

The crankshaft in the Valentine diesel 049 is standard TD 049.

The piston rod is the first thing to break in a TD 049 conversion.

Sounds like a fuelstarvation to me.  The engine is probably running on prime only and once the prime is gone the engine stops and won't start again unless it's primed again.

Clean the needle valve assemby throughly.

Best NOT to scrub the copper coating off the top of the cylinder.  It's intended to help cool the engine by dissippating engine heat.

SD

The number of head gaskets varies depending on the amount of nitro in the fuel, barometric pressure(and altitude), and temperature. A good starting point is always one, no matter what. Then starting at 20% nitro, add one and again for every 10% increase in nitro. If you're really a performance guy, then it needs more compression or nitro in the hot weather and less in the denser air of cold weather.

If you saw a noticeable brown sheen inside the cylinder, then de-varnishing it might have helped. Don't ever over do it or you can take off too much resulting in a loss of compression. A Scotchbrite type pad with alcohol is good for the job and not too aggressive. 000 steel wool and alcohol can be used with caution, but wash everything that may have leftover steel on it under running water with soap. Then dry and oil immediately.

SuperDave wrote:Sounds like a fuelstarvation to me.  The engine is probably running on prime only and once the prime is gone the engine stops and won't start again unless it's primed again.

Clean the needle valve assemby throughly.

Best NOT to scrub the copper coating off the top of the cylinder.  It's intended to help cool the engine by dissippating engine heat.

SD

Dave is right. Flushing the NV assembly and venturi sprinkler with brake parts cleaner is a good way to clear it out.

mad monky wrote:Oh I forgot to ask,
Can a tee dee crank take the strain of a diesel head because i love diesels and fancy a miniature diesel.

Sorry to spoil the party, but I've seen crank pins come off Tee Dee .049s when dieselised..........mine included. And it had NEVER been over compressed.
I used a Davis head on one one of mine years ago in free flight Keil Kraft Piper Super Criuser, and after a few flights at great height the engine shut down but the prop. kept rotating, free wheeling all the way down model in a beautiful glide.

I don't think it's blockedin the nva because when i put some fuel tubing on to it and blow there is plenty of air geting through. I probebly won't dieselise it as there is no real need.

I will try it again today with more nitro in the fuel and see if a de tarnished engine with more nitro helps in any way.

What is a good starting point with the needle valve.

Thanks
Ben.D

mad monky wrote:

What is a good starting point with the needle valve.

Thanks
Ben.D

It varies but 3 turns is a good place to start. If it runs full speed for longer than burning off the prime, then dies, it's still too lean. Open another half turn. The idea it to get it running slightly rich and then adjust leaner to full speed. Never lean it any more than where it first peaks smoothly.

Do you know the history of this engine? If not, and none of the advice so far works, maybe someone has bored the venturi out. See if you can drop the butt end of a 1/8" drill bit through it. If you can, it's been bored for pressure feed and hasn't enough suction to draw fuel. The three sprinkler holes around the neck of the venturi are clear, right? And your tank is even height with the NV? And the fuel line is as short as possible?
Rusty

What Rusty is saying we see an awfully lot of USED engines that have been modiefied by previous owns and who koow whether the modifications were successful?

SD

Ok so i got new glow ingiter battery's and tryed it on my car fuel with one shim,it gave hethy bursts but was spitting fuel so i keped leaning it out but it didn't want to run and i was so frustrated i got the starter moter to it " carefully " wich i souldnt of done but it ran and it was at peak rpm then ran out of fuel. I primed it again and flicked it to start and even when its warmed and set up it only starts with an electric starter wich i am not happy about so what can I do.

Come on Monky, read posts.  You are defeating yourself by trying too hard!

When I say clean the needle valeassemby THOUGHLY that's exactly what I mean.  If you cant blow air though it that means nothing.  The needle valve body AKA spray bar has small holes that direct fuel spray downward toward the crankshaft.

Guess what happens if those small holes are blocked by castor oil goo?  (The engine runs EXACTLY as you describe.)

SD (SuperDave)

SuperDave wrote:...Guess what happens if those small holes are blocked by castor oil goo?  (The engine runs EXACTLY as you describe.)

Dave, he says it ran out the whole tank once he got it started. The spraybar must be feeding it. It sounds like a fuel draw problem having more to do with the venturi, sprinkler holes, tank position, or other tank issue.

Of all the suggestions I've made, Ben hasn't confirmed, denied or described any findings, so I have no more idea which path to follow. I'm throwing things out that can be a problem, but need to have a methodical trouble shooter on the receiving end.
Rusty

Rusty:

Maybe if Ben consulted some knowledgeable person who could examine the engine first-hand................................ (like EX Model Engines) the solution could be found.

SD

How is the compression Ben,

Seeing as you have ran a tank through it i wouldn't think it's a fuel delivery issue. Troublesome hot restarts are a sign of low compression.

Also, in my experience low compression engines will sometimes start and run, but as the cylinder/piston heats up they expand and will stop running.

Just a thought. Do you have another piston/cylinder you can use. It need not be a #5 justone with a good fit to test with.

Ron

Cribbs74 wrote:How is the compression Ben,

Seeing as you have ran a tank through it i wouldn't think it's a fuel delivery issue. Troublesome hot restarts are a sign of low compression.

Also, in my experience low compression engines will sometimes start and run, but as the cylinder/piston heats up they expand and will stop running.

Just a thought. Do you have another piston/cylinder you can use. It need not be a #5 just one with a good fit to test with.

Ron

Compression, good thinking. Definitely worth looking into. My .051 is losing it too.
The reason I was still on fuel delivery is that, as a Tee Dee novice, I had frustrating bench cranking before I realized Tee Dees naturally don't suck as hard as Bees, or were easy to flood if the tank was too high. Once running, they are off to the races. Ben's apparently will run the tank out if he can coax it to crank.
Rusty

Ok but it ran. It's just hard to start and I'm guessing its nitro content. What is the correct prosidure to start this engine.

Thanks again
Ben.D