TED20 Cuts out

dchidell

New User
Hello,

I've got a TED20 Petrol/TVO model and after about 30 minutes it will splutter and misfire until it eventually dies. After 15 minutes or so it'll go again but only for another 10-15 minutes before it again dies.

I've done endless searching online and consulted with different people as to the cause - everyone suggests something different but is always good to know opinions.

The following parts have been replaced / changes made

[list:de611c37ee]
New carburetor
Intake / Exhaust manifold (Someone suggested a crack)
New intake / exhaust valves, springs and valve clips
New points
New condensor
New ignition coil
All wiring replaced and contacts cleaned
New ignition switch
New control / regulator box
New distributor cap
New rotor arm
New plugs
New HT leads
Various carb tweaks and changes
New fuel tank (old one was corroded badly and full of rust)
[/list:u:de611c37ee]

The following have been re-calibrated according to the Ferguson manual:

[list:de611c37ee]
Carb main / idle jets
Spark plug gap
Points gap
Tappet / pushrod clearances
[/list:u:de611c37ee]

A bit more info:

Starts and runs absolutely fine, no problems at all on tickover or startup.

Same problem occurs on both straight petrol and TVO.

Before re-doing valves had an episode of major backfiring, redoing the valves seems to have cleared that up (but this only occurred after replacing the carb, as well as after doing the pushrod clearances with the old valves.) Old valves did not appear too badly worn when replaced.

A lot of this work has been carried out over time, e.g. it's been over a year since many of the electrical components were replaced (points, condensor, distributor cap and rotor arm), but all appear fine.

I'm assuming that because the problem only seems to surface when hot, that this is the result of heat spreading to an area and causing something to fail. Given that almost the entire fuel system has been replaced I now suspect the electrical system. However most of this has been replaced as well!

Any ideas / suggestions would be more than welcome - replacing parts is not a problem, but it is rather frustrating to sink money into parts which don't actually solve the issue. (Although many of these components did appear to need replacement anyway).
 
Need to do some diagnostics when it is failing.

Be ready to check the spark as soon as it dies. Get an old spark plug, bend the electrode back so there is about 3/16-1/4" gap. Quickly pull a plug wire, put the test plug in the wire, lay the base against the engine, check the spark. If weak, check the voltage at the coil. If it's still 6 volt, it should be near battery voltage with the points closed. if low, check the ignition switch, any wiring between the coil, switch and battery. Should also get 0 volts on the point side. If voltage is present on the point side, points closed, the points have high resistance. Also remember, all ignition components are now aftermarket imports, not uncommon to be bad out of the box. Try another condenser.

Another thing to check, play in the distributor shaft bushing. If any wear, the points will not stay set, the gap will change, causing the points to arc and burn prematurely.

If the electrical checks out, go to the fuel system. There is a drain plug in the bottom of the carb. Again, do the test when it fails. With the engine off, fuel valve on, pull the plug, catch what comes out in a clean glass. There should be a full flow, slowing as the bowl emptied, but continuing as a stream. If it stops, or slows to a trickle, there is a fuel delivery problem. Common causes are clogged fuel valve or sediment bowl screen, clogged screen at the carb inlet, float set too low, non vented gas cap causing vacuum in the tank, inline fuel filter (paper filters are too restrictive for gravity systems), fuel line improperly routed (too close to exhaust causing vapor lock, kinked, looped), line should be steel, not copper.

Look at what was caught in the glass. If there is rust, grit, or water, that is what is in the carb. It may need to be cleaned, along with the tank.

Another diagnostic trick, on the fuel system, remove the carb drain plug, temporarily replace it with a barb fitting, slip a piece of clear vinyl tubing on the barb and bring the tubing up above the top of the carb, leave the end open. You can now monitor the fuel level in the carb while it is running.

Hope this helps, let us know...
 
I would agree that it is most likely to be electrical and again probably the coil , the symptoms are ones I have heard of many times before .
Ignition coils are of two major types , six volt coils made to work with a ballast resistor that reduces the 12 volts down to six for continuous use or straight twelve volt coils .
If you have the wrong one fitted the excessive heat produced with constant use will cause small breaks in the windings of a six volt coil . These remain ' closed ' while cold but open up with heat expansion leading to a frustrating intermittent breakdown of the ignition spark , made all the more perplexing as it is subject to time , engine rpm [ heat produced ] and ambient temperatures .
Try starting the engine and driving around the shed for five minutes , stop and let cool right down , do this four or five times during a day . If it doesn't breakdown then heat is the likely culprit . A known 12 volt rated coil may be all you need .
 
This tractor operates on a 12V system, not 6V.

The coil has been replaced again twice both supplied by Lucas.

The condensor has only been replaced once, so is certainly a suspect if they're known to come dead on arrival.

Are there any checks I can perform to test these components individually? Impedance through the coil, capacitance of the condensor etc?

I have my doubts about the points, they have also been replaced and the gap seems to remain constant and there's no evidence of any significant burning.

I am inclined to believe that this is heat related, if the tractor starts to cut out at high revs and it's shut right down, it appears to run smoothly idle and then behaves itself when revved up stationary making the problem quite difficult to diagnose properly.

There was a heat shield, which covered the exhaust / intake manifold however the manifold has been replaced and with a manifold for a TEA20 (no manifolds for a TED were available) so will only run on straight petrol at the moment. The old manifold had a serious crack in the side of the exhaust section which I believed may have been leaking into the intake when it gets hot and expands (although that doesn't seem so likely now it's not fixed the problem!)

Thanks for your comments - I'll certainly re-examine the coil & condensor.
 

The manifold crack is fairly common , I have a 1952 TED20 that had exactly the same thing happen .
You certainly have been thorough and it must be maddening to deal with .
One suggestion , a long shot , is the ignition switch in good condition ? Vibrations can break continuity and this would stop the engine instantly . To eliminate it is simple enough , substitute a toggle switch for it and see what happens .
 
The ignition switch was in awful condition - but it's been replaced, along with the entire wiring loom (which was also in awful condition, the wiring for the ignition switch actually fell off due to corrosion when inspecting the loom). It's now just a straight electrical switch, just as you said, alas with no improvement.

It certainly is maddening! Spending a bit of money here and there isn't a problem - but it's rather frustrating when a part is replaced and the problem isn't solved, especially when almost the entire ignition system and fuel system have been done.
 
There are some tests you can run on the electrical.

As for testing condensers, that can be difficult to get a "real world test". Best to just put in a known good one.

Points can be tested by putting them under load. Turn the engine until they are closed, turn the ignition switch on. Check for voltage from the point side of the coil to ground. Should read 0 volts. Try moving the wire around, poking around in the distributor, wiggling the point assembly. Any voltage indicates a poor connection. Failure at higher RPM is a symptom of bad points, so is exhaust backfire. Have you checked the position of the rotor in relation to the cap terminals when the points open? The length of the rotor electrode? The contact between the rotor and the center cap terminal?

The coil can be tested for ohms of resistance. Remove the primary wires from the coil. Check across the + and - terminals, including the resistor if used. For a 12v system, the resistance should be around 3 ohms. If low, the coil will overheat, add a resistor. If high, the spark will be weak. This test is really only to know the coil is in the right operating range, not a true test of performance. A healthy coil should produce a spark about 3/4" or more out of the tower. The coil will increase in temperature as it is running. Some heat comes from the ambient temperature, some from within, but it should remain cool enough to hold without too much discomfort.

The missing heat shield...

That is probably not going to cause problems operating on gas only, but I have seen them want to boil the gas in the tank on a hot day, working hard. If it can boil the tank, it can boil in the fuel line, starving the carb.

Have you tried a partial choke when it fails? If choking gives a temporary improvement, look at the fuel system closer.
 

You have a point Steve , fuel vapourisation may be occurring , though the absence of the heat shield on a TED usually doesn't cause this . That particular shield is there to increase the heat and warm the much larger cast iron boss at the base of a TED manifold , TEA manifolds are lighter at that point .

Has the fuel line been changed , perhaps with copper tube ? Copper will conduct heat far more efficiently than the original steel line . Does the fuel line rise slightly when crossing the bell housing on its way to the carburettor allowing a point for vapour to collect ?
 
The heat shield has only been removed very recently, and the issue was occurring when the shield was in place. In fact the only reason the shield has been removed is because I actually forgot to put the base plate on when bolting the head back onto the block. Since there were no plans to run the tractor on TVO (would like to at least get it working for more than half an hour first) I didn't bother to undo the head bolts and fit it.

The fuel pipe is funnily enough the only original component left of the fuel system and is most certainly steel.

When the tractor does cut out fuel runs cleanly out of the carb bowl tap so I am fairly certain that there is not a problem with delivery of fuel.

Steve you've made some great points about the coil and condenser so will have to give those tests a try when it's next convenient.

I've actually been referred by a colleague at work to a distributor supplier who supplies lucas distributors and ignition components which might be a good point of call to get some new components. Is anyone familiar with this chap?
http://www.distributordoctor.com/
I realise that quite a number of you are not in the UK, but can't hurt to wonder!
 

I have
Heard only good things about the distributor doctor . Of course I am in OZ but aquaintences in the UK have been happy with results. I From memory they also supply excellent condenser , caps and complete electronic ignition distributor replacements.
 
Ha dchidell

I have sort of followed this. One thing that caused my grief and a while to track down, simple as it is was., was a clagged up air cleaner.

IF you have an oil bath cleaner has the wire mesh been removed and cleaned or replaced.
 
people talk about side ways slop in the distibutor shaft bearing. I have it in all 3 of my TED20 and they run great.

Easy test, is to use a dwell meter. Use this to see if you have variation in the points ...
 
The air cleaner I wouldn't imagine to be a problem - everything runs fine until the tractor gets hot, and I can't see how a clogged air cleaner impact that. I've checked over it just as part of general maintenance and everything looks fine, oil is clean, gauze is clean etc etc. It doesn't do work in any dusty environments so shouldn't get clogged.

As for the slop in the distributor bearing, there's no play in the shaft (using the professional approach of trying to wiggle it). But also I'd expect this to cause poor performance from cold. I don't have a dwell meter to test it properly either.

I've got the parts from the distributor doctor (I got new points, rotor arm and condenser) so will have to see if that makes a difference, although it will be a couple of weeks before I can fit them.
 

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