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Td6 won’t start on petrol


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I’m at my wits end with it, it was getting hard to start so I gapped the points and greased the gears that drive the rotor cap, then aligned the gears correctly with the tiny L mark and the smaller gear bevel,  after that the only way I can get it to sputter is to turn and clamp the mag at around 40 degrees clockwise rotation, I have marked the mag where the points open and when the engine is at TDC on compression , the drive from the engine is around 90 degrees out to line up with the mag drive, its looking like someone has had the engine magneto drive off at the hour meter and put it back in the wrong timing position , then adjusted and rotated everything else on the mag to get it to run contrary to all the correct timing marks, what I’m chasing is the correct position of the mag drive on the engine to see if my theory is right, I have already gone through the inlet manifold and checked the butterflies are closing properly, checked and cleaned the carby, checked all the valves are not sticking, and the starting valves are opening, I’m getting good spark at the plugs, any thoughts or ideas would be greatly appreciated.

reg

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first thing i would do is verify if where the mag is tripping for #1 cyl on compression at tdc. watch the timing marks as your hand cranking it to tdc on the compression stroke. then u go from there. 

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3 hours ago, rustred said:

first thing i would do is verify if where the mag is tripping for #1 cyl on compression at tdc. watch the timing marks as your hand cranking it to tdc on the compression stroke. then u go from there. 

I have timed the tripping point on the mag as per the manual, when checking with a timing light the M mark is nowhere in sight of the pointer on the harmonic balancer 

reg

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2 hours ago, Rawleigh99 said:

Reggie:  I assume that while you were in the manifold you verified that the mag ground switch on the end was functioning properly?

Everything checks out ok as I am getting a good spark jumping at least 4mm at the end of the leads at the plugs.

reg

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1 hour ago, reggievonruffnut said:

I have timed the tripping point on the mag as per the manual, when checking with a timing light the M mark is nowhere in sight of the pointer on the harmonic balancer 

reg

well find out where it is then go from there. dont need a timing light. u need to turn the engine ever so slowing so that the instant the mag fires you can see on the pully where this is happening. then look at the rotor also and see where its pointing. then u can procced . #1 wire position on the mag is at 2 oclock. 

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i dont know what all you have done with this mag,... but that diesel engine has a left hand rotation mag. ... so do you have the marks lined up as in my photo? the r is for right hand rotation in the gas mags.

IMG_2613.JPG

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1 hour ago, rustred said:

well find out where it is then go from there. dont need a timing light. u need to turn the engine ever so slowing so that the instant the mag fires you can see on the pully where this is happening. then look at the rotor also and see where its pointing. then u can procced . #1 wire position on the mag is at 2 oclock. 

I have the magneto gears aligned correctly for counterclockwise (L) rotation and I have the magneto set to trip at the M mark on the harmonic balancer and pointer, and it won’t pop at all , it will only sputter and almost run if I rotate the and clamp the magneto 40 degrees towards ( clockwise) the RH side , which is 50mm beyond the bolt holes to hold the mag to the drive housing, I can’t rotate the mag anymore and clamp it beyond that point 

reg

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I need to know the correct position of the magneto drive on the engine side of the magneto, there is only 2 possibilities left that can be out of whack, the magneto drive on the engine side not timed correctly or the magneto drive on the magneto is not aligned with the keyway on the shaft, but the latter is very doubtful because the rotor is in the correct position and the points are opening at around the same place.

reg

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1 hour ago, reggievonruffnut said:

I need to know the correct position of the magneto drive on the engine side of the magneto, there is only 2 possibilities left that can be out of whack, the magneto drive on the engine side not timed correctly or the magneto drive on the magneto is not aligned with the keyway on the shaft, but the latter is very doubtful because the rotor is in the correct position and the points are opening at around the same place.

reg

well u got to get  #1 cyl .on tdc on compression. then pull of the mag. drive . then rotate mag so the points are just to open for #1 cyl. then you see where the mag drive slots position is. then you install the drive gear back in. so that both are matching. i just did this procedure this fall on a wd9.  i did not use any manual either just figured it out on my own. tractor fired right up on the first crank. i also rechecked my timing so everything was  spot on with timing marks on the front pully when the mag clicked.   

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30 minutes ago, rustred said:

well u got to get  #1 cyl .on tdc on compression. then pull of the mag. drive . then rotate mag so the points are just to open for #1 cyl. then you see where the mag drive slots position is. then you install the drive gear back in. so that both are matching. i just did this procedure this fall on a wd9.  i did not use any manual either just figured it out on my own. tractor fired right up on the first crank. i also rechecked my timing so everything was  spot on with timing marks on the front pully when the mag clicked.   

Yes that’s what I have done, the magneto drive and slots are not lining up, there is 90 degrees difference between the two slot and dog interfaces, I have never had the engine mag drive off ever, and normally put the mag rotor gears back the way I found them, I didn’t even know there was timing marks on them until this latest debarkle. How hard is it to change the engine mag drive position? Is it just undo the housing bolts and rotate the drive or is it a bit more involved?

reg

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9 hours ago, rustred said:

first thing i would do is verify if where the mag is tripping for #1 cyl on compression at tdc. watch the timing marks as your hand cranking it to tdc on the compression stroke. then u go from there. 

As rustred has indicated, make sure your at top dead centre on the compression stroke when rotor is at 1 position.. is it possible it may be 180 degrees out, and the spark is generated when the piston is tdc on exhaust stroke ?? 

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10 hours ago, reggievonruffnut said:

Yes that’s what I have done, the magneto drive and slots are not lining up, there is 90 degrees difference between the two slot and dog interfaces, I have never had the engine mag drive off ever, and normally put the mag rotor gears back the way I found them, I didn’t even know there was timing marks on them until this latest debarkle. How hard is it to change the engine mag drive position? Is it just undo the housing bolts and rotate the drive or is it a bit more involved?

reg

"are not lined up",... that is why i said to unbolt the drive housing from the timing gear housing. and pull it out. and match the mag housing slots to where the mag slots are then slide the mag gear back in. as i said before do this with #1 on TDC on COMPRESSION. PLUS THE MAG ROTOR HAS TO BE POINTING TO THE 2 OCLOCK POSITION ON THE CAP, AND JUST MATCH UP THE MAG DRIVE TO THAT. if you look very close at the timing gear i think it has a slight slant on one tooth. i mark the teeth with white marker on both so i can  watch to make sure i get the 2 gears matching when sliding them in.

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On 2/2/2022 at 2:46 AM, rustred said:

"are not lined up",... that is why i said to unbolt the drive housing from the timing gear housing. and pull it out. and match the mag housing slots to where the mag slots are then slide the mag gear back in. as i said before do this with #1 on TDC on COMPRESSION. PLUS THE MAG ROTOR HAS TO BE POINTING TO THE 2 OCLOCK POSITION ON THE CAP, AND JUST MATCH UP THE MAG DRIVE TO THAT. if you look very close at the timing gear i think it has a slight slant on one tooth. i mark the teeth with white marker on both so i can  watch to make sure i get the 2 gears matching when sliding them in.

I haven’t had a chance to realign the mag drive on the engine side , hopefully will get to it in the next couple of days and will report back whether it’s successful or not.

reg

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On 2/1/2022 at 4:57 PM, north of 60 said:

As rustred has indicated, make sure your at top dead centre on the compression stroke when rotor is at 1 position.. is it possible it may be 180 degrees out, and the spark is generated when the piston is tdc on exhaust stroke ?? 

I have found the TDC on the compression stroke for timing the magneto on or just past the M mark, 

reg

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  • 3 weeks later...

Hi Reggie, I’m having a similar problem, I too have checked everything as far a mag timing etc. so I took the intake manifold off and checked the butterfly valves. They look like new, so I measured the linkage on the starting valve operating lever. At 6 7/16”, right on, next removed the valve cover and operated the compression relief lever, it works great. So I’m back to the carburetor. I split the float bowl off. Made sure everything was working and blew out the pick up tubes. If this doesn’t work I’m back at the starting line.

please post if you get it running. We need to know what the solution was.

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53 minutes ago, Tracksbeatwheels said:

Hi Reggie, I’m having a similar problem, I too have checked everything as far a mag timing etc. so I took the intake manifold off and checked the butterfly valves. They look like new, so I measured the linkage on the starting valve operating lever. At 6 7/16”, right on, next removed the valve cover and operated the compression relief lever, it works great. So I’m back to the carburetor. I split the float bowl off. Made sure everything was working and blew out the pick up tubes. If this doesn’t work I’m back at the starting line.

please post if you get it running. We need to know what the solution was.

for both of you try starting fluid high grade FRESH gas ,then go back and 10X the basics and suspect the spark circuit

at this point I park next to and swap in 1x ,known running, 2 minutes ago electrics

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When mine doesnt fire up like it usually does I immediately go to filing points, just a quick cleanup almost always delivers the difference 

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May not be your issue but I had one of my TD-6s that got really hard to start. After checking the normal stuff which all seemed to be working ok it still wouldn't start unless i cranked it for a very long time then it would barely run then stall. The spark looked good but after a lot of reading for a couple months I found an old topic on a vintage car site that talked about plugs firing but not under compression. I found a spark tester that you connected to a plug wire then an air hose. The instructions mentioned how much air pressure would supposedly simulate a certain range of compression. Found out if I applied even the slightest amount of air pressure the spark stopped immediately. I replaced the coil in the mag and its ran perfect ever since.

On another TD-6 I had an aftermarket condenser in the mag that was about a third shorter than the originals and it would just sit against the case for a ground. It oxidized and then it wouldn't start so I found a different one that was the correct length that would clamp under the grounding clamp / holder and that fixed it.

 

Again may not be your issue but just what I experienced with a couple of mine.

 

Good luck!

 

Ken

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I have a TD14A that took an awful amount of cranking and some starting fluid to get it to start.  Once started and on diesel it ran quite good for a machine that sat in an open field for 10 years. I tried a short version new (Chinese) condenser but put the old one back in.  Finally replaced the coil and now it fires easily on gas when starting.  And it got new plugs once I got it home from the seller as a place to start, if it would help.  The magneto's are the same from the TD6 through the TD14's as they are all 4 cylinder engines.  My TD6 has a distributor wo that isn't an issue.

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  • 2 weeks later...

Well I finally got to the bottom of the problems which were making it impossible to start and got it going, the main problems were the points, the rotor cap being flogged out & the coil not producing a strong spark and the resin encasement disintegrating, with the points it wasn’t the contacts worn but the bit that rides on the cam, it was worn away by 2-3mm, when it wears away at an angle over time it retards the opening of the points in relation to the magneto timing, the rotor cap was flogged out inside where the lug locates it’s position on the drive, the coil was giving a weak spark also. So I got a new coil, condenser, rotor cap , distributor cap and it started up after a couple of revolutions.
Something that was invaluable was the IH H4 rebuilt information someone else privately gave me , it gives the magneto points timing in relation to the actual magneto, the points should open between 1/8” to 3/16” past  where the magnet bridges and holds between the air gap. 
Thanks for all the input

reg

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Good to hear ....I have seen the cam follower on points wear down because of the rust that forms on the Dist/Mag. cam from sitting out.

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Rubbing block is crappy quality nowadays vs older points, you may revisit this again in the future

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