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Thinking TEE DEE Having issues

Post  MANDALAY Thu Oct 31, 2024 9:49 pm

Went on a buying spree for cox engines . All new about 22 .
Ranging Black Widow 0.049,0.74,0.09 RC with mufflers , Tee Dees 0.049 and 0.09

I bought a lot.

Unfortunately I am realising the frustration to start these engines Sad

Reed valve Black widow, Golden Bee no issue

Cannot start the Tee Dees , I tested the glows , ok , I can hear the sizzel and i prime.

The 0.074 Tee Dee RC the same however when I remove the muffler on the 0.074 I can start no issue . Well that has a reed also.

What the secret on Tee Dees ?    

I would hate the 5 grand or so I spent only to be in a display case.


Last edited by MANDALAY on Thu Oct 31, 2024 9:51 pm; edited 1 time in total (Reason for editing : added)
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Thinking Re: TEE DEE Having issues

Post  MANDALAY Thu Oct 31, 2024 10:23 pm

TEE DEE Having issues Cox_en10

Add to the others outside , several Black Widows , few 0.074 RC and 0.09 RC and a 0.15 .
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Post  1/2A Nut Fri Nov 01, 2024 12:03 am

Solid 1.5v orange glow from the glow plug with true 1/2A fuel should start the engine with the right prop.
Note the nitro content 24% and oil type.

This example for sale on Ebay:

https://www.ebay.com/itm/226420990698?_skw=1%2F2A+fuel&itmmeta=01JBK1AT0G3RHZ8SAR4GV34T0Y&hash=item34b7be22ea:g:-pwAAOSwhOZlMDMB&itmprp=enc%3AAQAJAAAA4HoV3kP08IDx%2BKZ9MfhVJKk5PqtSttIUdyCavcIu3%2BvkKOvushsVtZyBdWj7CAjBw75UG9f554j6cSQ3E0xTNpYGPipL7SV49IjAYus5EutjrpqRkp12cAW2K0fi3mvRru2q2nGJALFUsRVER1OXLe3CFqY88lv7hOMF1beO7se%2BHwC2atSM%2BmVFrD81beQhP4cZtjECh24CQH%2BRjbxgqVvvw1H5lTT81wsaobn%2F5LVOIK%2F61lQgpkc8rimDdoL3NKd9%2F7hvfskMQVTVIM3z5vJWQ8JZxdazLi7YscH3Bokr%7Ctkp%3ABk9SR7Kgq-HcZA

TEE DEE Having issues S-l16029


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Thinking Re: TEE DEE Having issues

Post  TD ABUSER Fri Nov 01, 2024 5:02 am

The very first TD .049 I bought was in the 1980s and it refused to run.
My reed valve ,049s ran OK
I gave up and put the engine in storage
A few years later I  got interested in 1/2A control line combat and a knowledgeable friend took my TD apart and  put the parts in a sonic cleaner.
[his sonic cleaner was a jar full of solvent taped to an orbital sander].
Once the parts were clean he installed the crankshaft to the case and put on a propeller.
He flicked the propeller and it wouldn't spin  easily, so he chucked the crank into a drill motor and used a very fine [800..?] grit cloth for just a few seconds on the crankshaft journal and then did another test flick of the prop.
The prop should spin freely for a few seconds with model engine fuel as a lubricant. [This check is done before you install the piston and cylinder]
This engine started and ran very well after my friend did this final fitting of the crank to the crank case.
This was the only TD I ever bought that had this problem.
When you test flip a model engine prop, the crank should be free enough for the prop to toggle back and forth a few times as it bounces back and forth from the compression seal at TDC
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Thinking Re: TEE DEE Having issues

Post  balogh Fri Nov 01, 2024 8:38 am

Contrary to a tight shaft to crankcase fit, I had starting problem with a loose shaft fit as the aftermath of the previous owner running the engine with unbalanced prop and excessively wearing the crankcase nose.

You may want to check if there is any sensible radial "play" of the shaft in the case (simply wagging the prop while holding the crankcase firmly), because an excessive radial play will compromise the crankcase seal and lead to fuel drawing, and starting problems
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Thinking Re: TEE DEE Having issues

Post  Ken Cook Fri Nov 01, 2024 7:53 pm

If these are used TD's, the plastic carb bodies are prone to cracking. You can hardly see some cracks but they occur in the threaded area where the venturi screws in. A loose venturi, a cracked carb body or blocked peripheral jets within the venturi will compromise fuel delivery. The TD utilizes a large throat area within the venturi. This in itself can make the engine a bit more difficult to run over a integral tanked Bee.
Some people like myself will drill the venturi out for even more power but the problem occurs when you have a drilled venturi and your trying to run the engine from a tank. I rarely run TD's from tanks, all of mine are run using bladder pressure.

A new TD can also be a bit cantankerous when first trying to start especially with the hi-comp glow head. Decompressing the engine by adding additional head shims can make the engine more docile and easier to start. This may require 3-4 head shims. I'm personally not overly impressed with the needle valves of the TD. These can also suck air causing further fuel delivery problems. I do away with the spring steel ratchet under the venturi . I place a small piece of fuel tubing onto the needle valve which acts as a gasket between the spraybar inlet.

Get the engine to fire up on prime a few times prior to hooking up your fuel line and don't over prime the engine. After you burp it out a few times hook up your fuel line and open your needle about 4 turns. You should be able to place your finger over the venturi totally blocking it and rotate the propeller. The fuel should visibly be seen coming up the line and into the spraybar. Stop choking and prime cylinder and flip.
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Post  davidll1984 Sat Nov 02, 2024 7:01 am

I have a lot of experience with tee dee and I admit that the tee dee is slightly more difficult to start especially with a silencer my trick for an easy start is do Not prime over by the silencer But rather place a finger on the vetury and turn a few turns until you see the fuel rise in the pipe continue until the fuel enters the engine but do not drown it with fuel I like the .049 with the starter spring a well primed engine feels like this As you turn the propeller with your finger you should feel the compression and the engine giving a small start to ignition this Will offers good resistance sometimes giving a small slow explosion sort of bump on the prop At this precise moment the engine is ready so you give a good swing on the propeller and it should start With the spring starter it's better One thing many do is crank non-stop without even preparing the start with a fuel prime. Or insert too much fuel through the exhaust port which is dangerous and can hydrolock the engine causing possible damage. Too little or too much fuel is harmful and makes starting difficult.
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Thinking Re: TEE DEE Having issues

Post  MANDALAY Wed Nov 13, 2024 10:54 pm

Sorry for the late reply.
Im using Brodak fuel.

I dont think the fuel is the issues.

All my engines are new, great compression. Tried now 5 engines which are now classified as used.

Cannot start TEE DEE engines. Reed valves no issue. Take for instance the 0.074 no issue .

It is annoying . I might just set up to use the Black widow and 0.074 engines. I have 5 of them new. However they are hard to gauge with flooding with the muffler attached so I took it off.
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Thinking Re: TEE DEE Having issues

Post  GallopingGhostler Wed Nov 13, 2024 11:38 pm

@MANDALAY , did you purchase the problem Tee Dee's from Cox International? Bernie put out a message in:

https://www.coxengineforum.com/t18552-049-tee-dee-needle-valve-bodies-and-049-td-engines-potential-flaw

It is about  a manufacturing defect on his most recent TD production run. If you didn't purchase one of these or other Tee Dees from him, there still is a possibility of a defect in an Estes manufacturing run. I said possibility, because I really don't know.

I'm sure that there is a logical explanation for why there is no fuel feed to your Tee Dees, only running on prime. Also, it is possible that the versions you have, someone modified the venturi opening larger than factory?

They were designed to work under suction feed, but if enlarged, may require a pressurized fuel system (bladder, etc.). Because the suction feed is through a sidewall hole(s) in the venturi throat, the opening is smaller than would be for a spraybar visibly crossing the venturi opening.

Anyway, there are no rocket science issues, and I am sure that once you find the culprit, will be able to get them running, or, get them fixed then run.
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Post  TD ABUSER Sat Nov 23, 2024 9:43 pm

GallopingGhostler wrote: Also, it is possible that the versions you have, someone modified the venturi opening larger than factory?

They were designed to work under suction feed, but if enlarged, may require a pressurized fuel system (bladder, etc.). .

I just took a look at his stash and one of the engines looks like it could have an enlarged venturi.
I think 5/32" was the upper limit for a bladder fed .049 venturi
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Post  Ken Cook Sun Nov 24, 2024 7:10 am

Bladder pressure has no limits, it's when you drill out the venturi past 5/32" is when you break into the peripheral jet holes. This will no longer work when using the engine on suction if this is done.
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Post  balogh Sun Nov 24, 2024 7:42 am

I know this is no consolation to anyone having issues with TeeDee-s , but I have never had any starting or fuel suction problems with any of the Tee Dee-s in the 010...020...049...050...051 size range...no pressurized bladders nor elevated tanks were needed for an easy start and strong run lasting till the last drop of fuel in the tank...true though, that the venturi in my TeeDee-s are all stock i.e. not widened.

What I found beneficial was the use of a silicon tube on the NV threads extending over threaded nipple of the carb, to prevent air leakage along the NV threads, and making sure the crankshaft to crankcase fit was not destroyed by the prior use of unbalanced props...a radial gap in the crank nose equals compromised seal and lost vacuum in the crankcase when the piston moves up and fuel is to be sucked...needless to say the plastic carb body needs to be checked time-to-time  for the notorious cracks near the venturi threads..

Where the suction problem hits more often is with my TeeDee 090-s...even with stock venturi diameter, or with stock R/C carb, the unpressurized  tank should really be level with the carb, otherwise fuel starvation is expectable...
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