TD 6 Gas Engine will not start

I have owned a TD 6 crawler for nearly 15 years. I tried to start the gas engine side recently after the crawler had sat for over two years in the weather. No luck! I have replaced points, distributor, etc. and have good spark at the plugs. Fuel is getting to the carburetor via gravity feet. Intake is drawing air when cranking but the engine does not even cough when ether is applied.

I have a 1000 cranking amp battery and have force-started the dozer directly on diesel without going through the gas side. This is quite and effort. After running on diesel for a while, I attempted to convert back to gas but no go. Anyone have any ideas about what might be going on. As far as I can tell, I have checked spark, fuel and air.

Try a set of new plugs. Also you say you have spark but is it a good blue/white and will it jump a 1/4 inch gap or more. Years ago I had a TD-6 and it could be a real pain to start at times. Also make sure you have a good flow of gas out the carb drain plug.

Tried the new plugs but spark looks really good. I suspect fuel issue with carb but cannot figure out why it won't fire using ether. putting my hand over the intake, I could feel vacuum so I figure the ether was getting directly to the cylinder. I wonder if there isn't something going on with the compression and the carburetor. Thanks for the hints.

Are all of the manifold butterfly valves opening?
Seems like I had that problem with a TD 15, I found
that two or three of those manifold valves had stuck
closed.

Wow almost the same thing my ol TD-9 is doing.. It was starting so well too. Starting it on diesel seems like it would be hard on the starter to me.
I had mine running on gas (running very ruff) and slipped it to diesel quickly fired right off. Then I thought I might swap it back over to gas to help clear it up. That was the last it ran.
I have
reset mag timing, about 100 times.
replaced condenser
checked mag points
new wires
New Carb gaskets
checked manifold butteries
new plugs
stretched the electrode out to a 1/4" on an extra plug and used it to check the spark, spark was orange and bright.
Can't think of anything else.
maybe some idea here will help
good luck

I know you probably have checked but are both levers in the gas start position?? And if they are do they both move the parts they should so it can be in gas mode?? Also if you hold your hand over the air intake of the carb you should get gas on your hand if you do not yep fuel not getting into the carb

TD-6 right? Is that an updraft carb too? if it is you will still get a draw of air through the manifold intake even if the butterflies are not opening, will be drafting through the diesel side, but you will not get any vacuum through the carb nor gas/starting fluid in the manifold or the sparked chamber.

If the third valve adjustment has slipped and the decompression valve is not allowing enough air/fuel flow by could be a small possibility.

Just a thought but check compression rings on plugs and make sure the plugs are seating correctly. If not you could be losing too much compression. It should still fire on starting fluid though

How many turns out is your slobber jet on the carb? also Check to see if the carb float is working correctly. If the sparked chamber is flooded it may have trouble firing even with starting fluid.

Do you have the firing order and arrangement of the spark plug wires correct? You do know that the distributor turns counterclockwise, right?

just out tinkering with the ol TD-9 and found the carb manifold gasket was saturated with gas so I cut another two gaskets and sealed them together and put a thin film on both sides of the gasket with seal-all and let dry. I'm assuming the mating surfaces between the carb and manifold are not flat.

UPDATE
Went out put the carb on and it is firing a lot better now it needs to be warmer. Had it started and it ran out of gas????? It should have had a full tank of gas. ????? Hummm??? .....

I may have found one reason why the TD-9 is hard starting in cooler weather.
I started working backwards from the time I first started working on the TD-9 engine. Taking things back apart that I had disassemble and rechecked clearances, linkage yada, yada, yada...
I got back into the carb and found the Metering Well was tight but not allowing the Metering Nozzle to seat properly.
I noticed the Metering Well was not seated all the way agents the carb body, three or four threads of the Metering Well were still showing. I plugged the Metering Well port holes, see pic, with my fingers and blew air through the Metering Well. I could hear air flow and plugged the Metered hole on the carb body. I could still hear air flow past the seat [b:c56a9c50f3][i:c56a9c50f3][u:c56a9c50f3]inside[/u:c56a9c50f3][/i:c56a9c50f3][/b:c56a9c50f3] the carb body #52.
I removed and cleaned #54 Metering Well and #53 Metering Nozzle. I cleaned and re-cut the threads on the brass Metering Well until carb body accepted all the threads.
I replaced Metering Nozzle and tightened the Metering Well re-applied the pressure test and heard no flow by inside the carb body.
Now the vacuum from the manifold can draw gas through the carb at a better rate for the engine to run/start.
Good luck..
Fat Dan



[i:c56a9c50f3][u:c56a9c50f3][/u:c56a9c50f3][/i:c56a9c50f3]

Another Up date
I drained the antifreeze heated it up and put in a new tank heater pulled the plugs and cleaned them up. While heating cylinder head with a small propane torch I burned excess fuel out each cylinder individually and heated the gas and diesel sides of the intake manifold.
Poured the heated antifreeze back in to help preheat the block. I had the carb jet turned out up to 5 1/5 tuns and turned it out to 9 turns.
The engine started, while cold I tired to adjust the carb jet by turning it inward and the engine died. Restarted engine and cranked up on diesel.

I found one more thing holding back the engine from starting.
The gas/start lever was not all the way agents the stop; not allowing the third valve to open enough to start properly. The valve was open just enough to allow the engine to fire and pop but not start.

(quoted from post at 12:27:03 01/26/15) Wow almost the same thing my ol TD-9 is doing.. It was starting so well too. Starting it on diesel seems like it would be hard on the starter to me.
I had mine running on gas (running very ruff) and slipped it to diesel quickly fired right off. Then I thought I might swap it back over to gas to help clear it up. That was the last it ran.
I have
reset mag timing, about 100 times.
replaced condenser
checked mag points
new wires
New Carb gaskets
checked manifold butteries
new plugs
stretched the electrode out to a 1/4" on an extra plug and used it to check the spark, spark was orange and bright.
Can't think of anything else.
maybe some idea here will help
good luck

Click to expand...

Just a note on this for what it is worth. 1/4 inch gap on the spark plug for a mag should = a fat BLUE spark. Almost white. I have fought tractors and equipment for days that had "spark" Once combustion pressure is in the mix, ie spark plug back in the cylinder, an orange spark will not cut it. there is still something wrong. Think of a lighter versus a propane torch. My lighter will burn my hand, so will the torch, but my lighter will not solder wires together.

Just my two cents. Hope it helps
Adam

(quoted from post at 07:00:00 02/20/15) I found one more thing holding back the engine from starting.
The gas/start lever was not all the way agents the stop; not allowing the third valve to open enough to start properly. The valve was open just enough to allow the engine to fire and pop but not start.

Click to expand...

The Gas/Start lever was the main reason my TD-9 was not starting. I needed to adjust the starting mechanism so the lever stayed up on its own and held the start valve open far enough to get a sufficient amount of gas in the chamber to start and run.
Now it is starting quit well. Back to normal, Turn the crank to just past TDC (because it has bad spots on the ring gear). On COLD start, pull the choke all the way and turn over one to three full revolutions then push choke in to the sweet spot, about half way, and depending on the ambient temperature the engine should start on first try.

http://youtu.be/KLmCWhr0oAc