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743 Bobcat Glow plug / Starting Problem

J

Jack in Michigan

Member
Hello Everyone,
Hope I am not posting in the wrong area, if so please let me know. My buddy and I own a 743 bobcat together. It has the Kubota 4 cylinder diesel engine. In the past when it had been sitting for days without being started or when it would get colder out, it became very hard to start. I would hold the key in the glow plug position for up as much as 90 seconds or more and then it would slowly start and die, this would have several times before it would finally stay running. I purchased new glow plugs from Bobcat and glow plug relay. Now it does not matter how long I hold it in the glow plug position it will not start unless I give it a little (upper engine lubricated) starting fluid, and I wait for quite awhile before I introduce the starting fluid after the glow plugs are cooled down; that is if they are even working. Any help would be appreciated or if anyone has a manual with this page on it they could share.
Thanks,
Jack
 
Connect a test light between the terminal on each glow plug, one at a time, and chassis ground and have a helper cycle the key/operate the glow plugs.

Does the test light show that power is getting to the GP's during the pre-heat cycle?
 
do you get white smoke when it don't start? If not, you are not getting fuel. If you have fuel and lot's of white smoke, then it is a glow plug issue. If not, you have a fuel problem. Could be draining back. could be a pump issue, could be fuel filters. does it crank over real good? if it is slow cranking, it won't start.
Just a few ideas.
 
I am getting a lot of white smoke. Just replaced the fuel filter, primer pump and a brand new batter which makes it spin over easily. The fuel pump is working at least when we pulled the line off the fuel was flowing good. And just to make sure that I am giving all of the correct information, once you hit it with a small amount of starting fluid, it starts up immediately and runs good.
 
Jack fro all that I read on what you have done I am guessing your engine has low compression. Your starting fluid fires a little easier and lets the engine start. Probably going to have to have a ring job. The use of either on a KUBOTA engine is just about a no no. Here is something you might do , mix some diesel with gas in a 50/50 mix. Remove the breather tube and use something like a windex bottle and spray some in as you attempt to start the unit. If this mixture starts the unit WITHOUT the use of glow plugs pretty sure you have low compression.
 
That white smoke is unburned fuel ,, and the reason it is not firing is low compression. When you inject the starting fluid it has a lower flash point and fires. Thing is it also breaks the top ring and just makes the problem worse.. No expert but 28 years KUBTA experience and I would almost bet compression is low/
 
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