743 glow plugs?

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roadkill

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My 743 runs like a top but starts like a pig. I'm wondering if the glow plugs are fragile and if they just screw out like a sparkplug? You can't see them very well. The one closest to the door looks impossible to get out. The service manual just says to check them with an ohm meter. Input on removing and testing would be appreciated.
Also, the previous owner put the front light on on top of the cab, and I'm curious about how that comes off, so I can put it on bottom, pointed at the sky doesn't do much good.
 

skidsteer.ca

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Remove the wires connected to the glow plugs so that none are wired to the next. Take a wire test light and conect the ground clip on it to the Positive on your battery. Put the probe end against where you removed the wire (on the terminal) on the glow plug. If the element in the glow plug is good the test light will get a ground throught he glow plug element and the bulb in the test light will iluminate. No light = burnt out glow plug.
Regards
Ken
 

Tazza

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Remove the wires connected to the glow plugs so that none are wired to the next. Take a wire test light and conect the ground clip on it to the Positive on your battery. Put the probe end against where you removed the wire (on the terminal) on the glow plug. If the element in the glow plug is good the test light will get a ground throught he glow plug element and the bulb in the test light will iluminate. No light = burnt out glow plug.
Regards
Ken
That test will tell you if the plugs are burnt out or not, but unfortunatly they won't tell you if they are lazy or not. I had a set that tested just fine, BUT when i pulled them from the engine they were fat at the base and tapered to the end! I tested them on a battery and the base went red hot but the tip just stayed black. I was told they should start glowing from tip to base. You may have the same problem?
The machine started with glows of 60+ seconds, anything less and it just puffed white smoke and it would splutter then stop. When warm, 1 flick of the key and it was away.
The plugs just screw in, very simple. 3 out of the 4 plus are easy to get out, the last one is a total pig. Get a deep 12mm socket and you can easily get the 3 out. The one at the front i had to remove one of the injector lines to gain access to it. Ge hold of a 17mm flare nut spanner for this, getting in there with a standard spanner is really quite hard. You may even have to loosen the inlet manifold nuts to twist it to get the socket over the glow plug.
Unfortunatly i dont have the part numbers of the plugs. I paid like $20 AUD for a set of 4, it made a HUGE difference in starting.
 

bobbie-g

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That test will tell you if the plugs are burnt out or not, but unfortunatly they won't tell you if they are lazy or not. I had a set that tested just fine, BUT when i pulled them from the engine they were fat at the base and tapered to the end! I tested them on a battery and the base went red hot but the tip just stayed black. I was told they should start glowing from tip to base. You may have the same problem?
The machine started with glows of 60+ seconds, anything less and it just puffed white smoke and it would splutter then stop. When warm, 1 flick of the key and it was away.
The plugs just screw in, very simple. 3 out of the 4 plus are easy to get out, the last one is a total pig. Get a deep 12mm socket and you can easily get the 3 out. The one at the front i had to remove one of the injector lines to gain access to it. Ge hold of a 17mm flare nut spanner for this, getting in there with a standard spanner is really quite hard. You may even have to loosen the inlet manifold nuts to twist it to get the socket over the glow plug.
Unfortunatly i dont have the part numbers of the plugs. I paid like $20 AUD for a set of 4, it made a HUGE difference in starting.
Roadkill -- My 751 diesel was not starting well. All the plugs checked OK with an ohmmeter (1 ohm or less resistance) when tested individually. When I pulled one out and hooked it directly to the battery, it glowed nice and red hot all along the length. So everything seemed to check out OK, but I put in a new set anyhow (finally found some replacements by Bosch at 1/4 the Bobcat price). The difference was really amazing. Starts great now, just a slight bit of dark smoke for the first 2-3 seconds, then purrs with invisible smoke. Before, it would cough up white smoke, miss a bit, belch out dark smoke sometimes, sometimes not even start for the first few tries. Sure made a difference. And the Bobcat dealer didn't even mention that when I asked about hard starting. I'd sure consider a new set if you can find them reasonably. Mine were $9 each at Autozone. I called Bosch with the old Bosch number from the original glowplugs (1300 hrs on them) and found the direct replacement. I guess I'd apply Tazza's term to the old plugs: lazy. (I think it was Churchill that said the Yanks and the Brits were two peoples, separated by a common language!)---Bob
 

roadkill

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Roadkill -- My 751 diesel was not starting well. All the plugs checked OK with an ohmmeter (1 ohm or less resistance) when tested individually. When I pulled one out and hooked it directly to the battery, it glowed nice and red hot all along the length. So everything seemed to check out OK, but I put in a new set anyhow (finally found some replacements by Bosch at 1/4 the Bobcat price). The difference was really amazing. Starts great now, just a slight bit of dark smoke for the first 2-3 seconds, then purrs with invisible smoke. Before, it would cough up white smoke, miss a bit, belch out dark smoke sometimes, sometimes not even start for the first few tries. Sure made a difference. And the Bobcat dealer didn't even mention that when I asked about hard starting. I'd sure consider a new set if you can find them reasonably. Mine were $9 each at Autozone. I called Bosch with the old Bosch number from the original glowplugs (1300 hrs on them) and found the direct replacement. I guess I'd apply Tazza's term to the old plugs: lazy. (I think it was Churchill that said the Yanks and the Brits were two peoples, separated by a common language!)---Bob
Those darn plugs are so close to the intake manifold that I can't get a socket on.
emotion-9.gif
A 12mm open end is just sloppy enough that it slips over the corners of the “head” area. 11mm and 7/16 were too small, and 1/2” was way too big. I'm not sure what to do. Any ideas? I'm not too keen on taking the engine apart.
 

bobbie-g

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Those darn plugs are so close to the intake manifold that I can't get a socket on. A 12mm open end is just sloppy enough that it slips over the corners of the “head” area. 11mm and 7/16 were too small, and 1/2” was way too big. I'm not sure what to do. Any ideas? I'm not too keen on taking the engine apart.
Roadkill, presumably poor access to the plugs will not allow use of a hex flare-nut wrench (I don't know the real name for these gems, but they are like an open-end wrench, but wrap around the nut and grasp nearly all the flats). Another idea is to sacrifice a 12mm socket and just grind it down where ever it needs to be smaller (my father left me with a few of these modified sockets for specific hard-to-get-to places). I have occasionally purchased a wrench, then heated it with a torch and bent it to the right shape. Worked for me. Maybe a last resort is to use vise-grips, but if you round off the flats on the "nut" there's not much else to be done short of getting enough access to use yet a larger pair of vise-grips. The ones I removed (most likely factory originals) were not in very tight at all. I put anti-sieze compound on the new ones. As I recall, I had to remove an injector line to access one of the plugs, but that was easier that it sounds, including bleeding the air out after reinstall. I suppose last resort is to ask Bobcat to do it, but that's about $75/hr here. Good luck. ---Bob
 

Tazza

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Roadkill, presumably poor access to the plugs will not allow use of a hex flare-nut wrench (I don't know the real name for these gems, but they are like an open-end wrench, but wrap around the nut and grasp nearly all the flats). Another idea is to sacrifice a 12mm socket and just grind it down where ever it needs to be smaller (my father left me with a few of these modified sockets for specific hard-to-get-to places). I have occasionally purchased a wrench, then heated it with a torch and bent it to the right shape. Worked for me. Maybe a last resort is to use vise-grips, but if you round off the flats on the "nut" there's not much else to be done short of getting enough access to use yet a larger pair of vise-grips. The ones I removed (most likely factory originals) were not in very tight at all. I put anti-sieze compound on the new ones. As I recall, I had to remove an injector line to access one of the plugs, but that was easier that it sounds, including bleeding the air out after reinstall. I suppose last resort is to ask Bobcat to do it, but that's about $75/hr here. Good luck. ---Bob
Yo don't need to pull the engine apart as such, you just need to loosen the inlet manifold and remove 1 or 2 injector lines. Seriously, its not difficult, it just takes a bit of time. Give the inlet side of the engine a good clean before you start so you don't get any dust in the engine.
Remove the air intake hose, and un-do the bolts holding the manifold in place. You will need to remove i think number 2 and 3 injector lines at the pump, you will need to remove the 2 clamps holding the injector lines together. Remove the lines at the pump, and loosen them at the injectors and you should be able to swing them out of the way.
Remove and replace the glow plugs then re-assemble.
It does take time, but its not that difficult.
 

roadkill

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Yo don't need to pull the engine apart as such, you just need to loosen the inlet manifold and remove 1 or 2 injector lines. Seriously, its not difficult, it just takes a bit of time. Give the inlet side of the engine a good clean before you start so you don't get any dust in the engine.
Remove the air intake hose, and un-do the bolts holding the manifold in place. You will need to remove i think number 2 and 3 injector lines at the pump, you will need to remove the 2 clamps holding the injector lines together. Remove the lines at the pump, and loosen them at the injectors and you should be able to swing them out of the way.
Remove and replace the glow plugs then re-assemble.
It does take time, but its not that difficult.
I was hoping to get one out and see if there are numbers on it or if it's standard, and could be bought at an autoparts store. I would rather hold off tearing things apart until I have the replacements. Anyone know if they are standard or if they can be had at an autoparts? I haven't had a chance to check with the dealer (they're 40 miles away, so I'd rather get them at a nearby autoparts).
Also, how do the headlights come off? It only has one on it and it's on top, pointed at the sky. The parts manual doesn't show how it attaches.
 

Tazza

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I was hoping to get one out and see if there are numbers on it or if it's standard, and could be bought at an autoparts store. I would rather hold off tearing things apart until I have the replacements. Anyone know if they are standard or if they can be had at an autoparts? I haven't had a chance to check with the dealer (they're 40 miles away, so I'd rather get them at a nearby autoparts).
Also, how do the headlights come off? It only has one on it and it's on top, pointed at the sky. The parts manual doesn't show how it attaches.
You should be able to get the glow plug thats rite at the back of the machine out. Worst case use a 12 mm open end spanner. This one is the easiest of them all to get out.
If you have the stock lights attached, they are just a rubber housing, just jam a screw driver between the bulb and the rubber and twist it out.
 

roadkill

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You should be able to get the glow plug thats rite at the back of the machine out. Worst case use a 12 mm open end spanner. This one is the easiest of them all to get out.
If you have the stock lights attached, they are just a rubber housing, just jam a screw driver between the bulb and the rubber and twist it out.
The back one was accessible. I got plugs from a local Kubota dealerfor about $55 for four. They are ngk brand. I finally got around to changing them. I had to take the back injector line off. I couldn't get the second from back line off. I took all the intake manifold bolts out and could get access to the other three plugs, including the front hidden one. I've gotta try it a few more times, but it still didn't start well. I didn't do any fuel bleeding. I only tried it the one time, and haven't run it long. Hopefully it'll smooth out.
 

Tazza

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The back one was accessible. I got plugs from a local Kubota dealerfor about $55 for four. They are ngk brand. I finally got around to changing them. I had to take the back injector line off. I couldn't get the second from back line off. I took all the intake manifold bolts out and could get access to the other three plugs, including the front hidden one. I've gotta try it a few more times, but it still didn't start well. I didn't do any fuel bleeding. I only tried it the one time, and haven't run it long. Hopefully it'll smooth out.
I'm glad you managed to get them in.
What is it doing exactly? Does it start then stop, puff white smoke while cranking? Slow cranking?
Make sure your battery is good, if the battery is low, the starter will spin slower and the compression won't be quite high enough to start easily. It may be worth while taking the battery to your local battery shop for them to do a load test. Give it a good charge first!.
How long are you glowing?
Sorry for the million questions, but any of them could be causing you problems.
As for bleeding the injector line, just run it for a few seconds and it will have bled its self out.
For me, i generally glow for say 20 seconds, longer if its cold. If the engine has a few hours up i would start at say 30 seconds and work from there, Kubota engines really do like a nice glow. If i don't glow long enough, it will start and run rough blowing black smoke then it will catch and work well. On a machine i have with a lot of hours up, if you don't glow it enough it will start then just die, give it a good glow and it will start almost smoke-less.
My starter has a bit of noise in it so i changed it with another one i had, the new one spins much faster. Your starter may want a new set of brushes too.
Start with the battery and glow time, work from there.
 

goodtech

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I'm glad you managed to get them in.
What is it doing exactly? Does it start then stop, puff white smoke while cranking? Slow cranking?
Make sure your battery is good, if the battery is low, the starter will spin slower and the compression won't be quite high enough to start easily. It may be worth while taking the battery to your local battery shop for them to do a load test. Give it a good charge first!.
How long are you glowing?
Sorry for the million questions, but any of them could be causing you problems.
As for bleeding the injector line, just run it for a few seconds and it will have bled its self out.
For me, i generally glow for say 20 seconds, longer if its cold. If the engine has a few hours up i would start at say 30 seconds and work from there, Kubota engines really do like a nice glow. If i don't glow long enough, it will start and run rough blowing black smoke then it will catch and work well. On a machine i have with a lot of hours up, if you don't glow it enough it will start then just die, give it a good glow and it will start almost smoke-less.
My starter has a bit of noise in it so i changed it with another one i had, the new one spins much faster. Your starter may want a new set of brushes too.
Start with the battery and glow time, work from there.
12mm 6point 1/4 drive deep snap-on socket works great for those things
 

pondfishr

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Oct 11, 2005
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That test will tell you if the plugs are burnt out or not, but unfortunatly they won't tell you if they are lazy or not. I had a set that tested just fine, BUT when i pulled them from the engine they were fat at the base and tapered to the end! I tested them on a battery and the base went red hot but the tip just stayed black. I was told they should start glowing from tip to base. You may have the same problem?
The machine started with glows of 60+ seconds, anything less and it just puffed white smoke and it would splutter then stop. When warm, 1 flick of the key and it was away.
The plugs just screw in, very simple. 3 out of the 4 plus are easy to get out, the last one is a total pig. Get a deep 12mm socket and you can easily get the 3 out. The one at the front i had to remove one of the injector lines to gain access to it. Ge hold of a 17mm flare nut spanner for this, getting in there with a standard spanner is really quite hard. You may even have to loosen the inlet manifold nuts to twist it to get the socket over the glow plug.
Unfortunatly i dont have the part numbers of the plugs. I paid like $20 AUD for a set of 4, it made a HUGE difference in starting.
Tazza, I found this post where you mention 17mm spanner. Are you talking about a crows foot? And what can I screw up if I take the injector lines off?
 

Tazza

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Tazza, I found this post where you mention 17mm spanner. Are you talking about a crows foot? And what can I screw up if I take the injector lines off?
I did mine with *standard* open end spanners. You could use crows foot or flare nut spanners too, it would make it so you don't need to take more lines off to gain access.
You can't mess anything up, just don't un-do the delivery valve. If you hold the delivery valve with a spanner while you un-do the injector lines you cant go wrong! Even if they do turn a bit it will hurt nothing, just don't pull them all the way out, even then its hard to stuff them up. Just make sure if the delivery valves do move, tighten them back up before you start the machine, if they are loose they will leak fuel.
Any questions just yell! I have done this too many times before...... I just have never opened up a working injector pump, they need to be set exactly rite, its not something i will mess with.
OOH keep the delivery valve openings clean, clean the area before you start working just to be safe. Dirt could plug the injector nozzle, just keep it clean and you will be ok.
 
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