743 hard to start

Help Support SkidSteer Forum:

daved

Active member
Joined
Aug 9, 2008
Messages
34
Hey Guys I'm having a bit of problems cold starting my 743 if it sits for a week or so. Heres what it does. In 60 degree weather if it sits for week without being used I can turn the key backwards , I hear the selenoid to glow plugs click then I wait about 10 sec. it will hit puff smoke and die then I repeat this cycle it will fire off clear rite up 5 seconds later no smoke. Then it will start at the bump of a key all day. It seems to start easier if I use it daily. My thing is what If I want to use it to clear snow I dont know if a block heater would help if it does this in 60degree weather. Also this machine has 2500-3000 hrs and in very good shape so I dont mind spending the money to make it right. This has no blow by and doesnt smoke when it shouldnt. Whats the easiest way to check glow plugs and injectors. P.S. I just did a complete service 10 hrs ago on all the filters and most fluids. Any input would be much appreciated.
 
First thing i'd do is change the glow plugs. What you describe sounds exactly like what happens with bad plugs. Also, try glowing a little longer, try 15-20 seconds and see how you go. I had a machine that did this, glowed then spun it over, it would fire then just die. The plugs were hour glass shape and only glowed at the base, they must glow rite to the tip. When warm just one bump and it would be off, no smoke either.
 
First thing i'd do is change the glow plugs. What you describe sounds exactly like what happens with bad plugs. Also, try glowing a little longer, try 15-20 seconds and see how you go. I had a machine that did this, glowed then spun it over, it would fire then just die. The plugs were hour glass shape and only glowed at the base, they must glow rite to the tip. When warm just one bump and it would be off, no smoke either.
Tazza thanks alot, what can I expect to pay for the glow plugs for this little monster any ideas??
 
Tazza thanks alot, what can I expect to pay for the glow plugs for this little monster any ideas??
They should be around $10 each. You can buy these off a diesel shop or even a kubota dealer. You can get them off your dealer but i have no idea on price.
 
They should be around $10 each. You can buy these off a diesel shop or even a kubota dealer. You can get them off your dealer but i have no idea on price.
Dealer prices when I bought my 743 glow plugs ranged from $17 - $25. It helps to shop around.
 
Dealer prices when I bought my 743 glow plugs ranged from $17 - $25. It helps to shop around.
If you are going to take the glow plugs out to change then it would be a good time to check the compression as low compression is the most likely cause of hard starting
 
If you are going to take the glow plugs out to change then it would be a good time to check the compression as low compression is the most likely cause of hard starting
That is true, but good plugs do help!
Even if you pull the old ones out and test them with a cable and battery.
 
That is true, but good plugs do help!
Even if you pull the old ones out and test them with a cable and battery.
I have what is probably a stupid question on this subject, but my 743 is the first diesel I have ever had. Do you need to heat the glow plugs everytime you start the machine? In other words if I have had the machine running and turn it off to do something and start back up 5 or 10 minutes later do I need to fire up the glow plugs?
 
I have what is probably a stupid question on this subject, but my 743 is the first diesel I have ever had. Do you need to heat the glow plugs everytime you start the machine? In other words if I have had the machine running and turn it off to do something and start back up 5 or 10 minutes later do I need to fire up the glow plugs?
My knowledge of gas engines is better than diesel also.
To answer your Question I would say no to using them after the engine is warm. If your compression is good it should start without glow plugs down to about 45 F. Im going by my engine .
It may be easier on the engine when cold. After its warm I dont think it makes a differenceWould someone correct me if I am doing my engine wrong. Mike
 
My knowledge of gas engines is better than diesel also.
To answer your Question I would say no to using them after the engine is warm. If your compression is good it should start without glow plugs down to about 45 F. Im going by my engine .
It may be easier on the engine when cold. After its warm I dont think it makes a differenceWould someone correct me if I am doing my engine wrong. Mike
I agree.
If the engine is a little sad you may need to glow it every time you start. On my 753 it has excellnt compression and with moderate temperatures will start rite up, it does have a glow timer but this is key on then straight to start no waiting for it to glow. As long as the temperature isn't too low this should start rite up if left for 10-15 minutes if it was at operating temperature before you shut down. Its the sort of thing you need to play with till you get to know the engine and how it starts.
My 743 can be moody, when warm its no problem but if it cools off a bit too much i just give it a little glow and it fires rite up.
 
I agree.
If the engine is a little sad you may need to glow it every time you start. On my 753 it has excellnt compression and with moderate temperatures will start rite up, it does have a glow timer but this is key on then straight to start no waiting for it to glow. As long as the temperature isn't too low this should start rite up if left for 10-15 minutes if it was at operating temperature before you shut down. Its the sort of thing you need to play with till you get to know the engine and how it starts.
My 743 can be moody, when warm its no problem but if it cools off a bit too much i just give it a little glow and it fires rite up.
Thanks, Starts fine once warmed up, Just didn't want to hurt anything by not glowing. This engine only has 34 hours on it, so it has very good compression. I appreciate all the help
 
Thanks, Starts fine once warmed up, Just didn't want to hurt anything by not glowing. This engine only has 34 hours on it, so it has very good compression. I appreciate all the help
Not glowing won't hour the engine, it may be a little harder on the starter though. Give it a bit of glow for good measure, it won't hurt anything.
 
Not glowing won't hour the engine, it may be a little harder on the starter though. Give it a bit of glow for good measure, it won't hurt anything.
When I hear statements like " this engine only has 34 hours so it has very good compression " it makes me say hmmmmmm , I have learned take nothing for granted --------apparently something is wrong as it don't start like it is suppose to as I have seen over the years if it is above around the 60 degrees range a 'fresh' Kubota engine will start without any glowing , I am not saying it is a compression problem just that you can't not take compression or any other thing into considerations when trouble shooting because it only has 34 hour , a ring could have been broken during installation , or the rings may have never seated , the ring end gap not properly fitted , either could have been used to start it once and cracked a ring , the wrong oil used , dirt left in th block on rebuild , what ever , it is possibly a compression problem even if the motor was to have only .5 hours on it and shouldn't not be considered a possible cause
 
When I hear statements like " this engine only has 34 hours so it has very good compression " it makes me say hmmmmmm , I have learned take nothing for granted --------apparently something is wrong as it don't start like it is suppose to as I have seen over the years if it is above around the 60 degrees range a 'fresh' Kubota engine will start without any glowing , I am not saying it is a compression problem just that you can't not take compression or any other thing into considerations when trouble shooting because it only has 34 hour , a ring could have been broken during installation , or the rings may have never seated , the ring end gap not properly fitted , either could have been used to start it once and cracked a ring , the wrong oil used , dirt left in th block on rebuild , what ever , it is possibly a compression problem even if the motor was to have only .5 hours on it and shouldn't not be considered a possible cause
Always thinking posotive I like to think when someone tells me they have a fresh rebuild You take it that it was done right.
I have seen guys that think rebuilding an engine is throwing in a set of rings and bearings, scuffing down the cylinders with 600 sandpaper and reassembling with gritty hands. Ive been told I go overboard but I only want to do it once. Why waste money.
Im sure yours was done right. I have ran into what Fishfiles says.There are hammer mechanics out there. Mike
 
Always thinking posotive I like to think when someone tells me they have a fresh rebuild You take it that it was done right.
I have seen guys that think rebuilding an engine is throwing in a set of rings and bearings, scuffing down the cylinders with 600 sandpaper and reassembling with gritty hands. Ive been told I go overboard but I only want to do it once. Why waste money.
Im sure yours was done right. I have ran into what Fishfiles says.There are hammer mechanics out there. Mike
Funny you should say that, i fully re-built my V1702 2 years back, i don't think the machine shop did it rite. It has always been a pig to start and blows a bit of white smoke, when warm its great but at startup.... I need to give it a decent glow too. It has about 150 hours up and remains the same. I believe the piston to head height is not correct, my dad got it done at work and assured me it was done rite, so i didn't bother checking it. I had another block done and is ready to assemble and i figured i may as well check the piston to head height. It was about .040" too low, that may not seem much, but for a diesel it makes all the difference. It needs .040" removing from the deck of the block to be *rite*. The fuel system was fully done too, new sleeves installed and machined, head fully done.
If you are at all un-sure, give it a compression test, it should be in the high 400's, i *think* the factory spec for a new engine is about 475-500 PSI
 
Top