743 starting problems

[tjc]

Hello I am new to this forum, my name is Tom I am a retired teacher and disable veteran. I keep busy doing odds and ends around my father in laws mini ranch, like feeding horses, and moving gravel and dirt with my bobcat. which brings me to my problem. I have a 743 bobcat with a 1702 kubota engine. I used last fall to unload some hay, and after shutting it down for the day I went back to start it the next day and all it would do is turn over but no start. the tail pipe puffed of white smoke and I could hear gurgling sound coming from my radiator reservoir. Of course my first thoughts was it was not getting fuel, so I checked my lines, injectors, bulb, pickup line in the tank, pretty much everything dealing with fuel, changed bulbs, changed some fuel lines bleed the system nothing but turn over and no start. even though there is no oil in the water and no water in the oil, I am thinking a blown head gasket, but I can not be sure of that, and the fact it did not get hot and shut it self down I am not sure. However I used it a few weeks before this incident and it lost power and started to blow white smoke out the tail pipe however I did manage to get it loaded on the trailer and get it home, and used it to unload the hay, but now it will not start. any ideas?

 

[foton]

have you verified that all your glow plugs are working ?

 

[tjc]

I put them in new last summer, I pulled them again after it started acting up, they looked like new still. I did buy a new selenoid for the glow plugs but I haven't put it on yet, I wanted to be sure it's not a head gasket

 

[North Idaho Wolfman]

You more than likely have a cracked head.
Pull the radiator cap, fill full of water and look for bubbles.
Bottle feed the injection pump fuel with fuel to eliminate any fuel delivery issues.

 

[KJB1066]

Hello I am new to this forum, my name is Tom I am a retired teacher and disable veteran. I keep busy doing odds and ends around my father in laws mini ranch, like feeding horses, and moving gravel and dirt with my bobcat. which brings me to my problem. I have a 743 bobcat with a 1702 kubota engine. I used last fall to unload some hay, and after shutting it down for the day I went back to start it the next day and all it would do is turn over but no start. the tail pipe puffed of white smoke and I could hear gurgling sound coming from my radiator reservoir. Of course my first thoughts was it was not getting fuel, so I checked my lines, injectors, bulb, pickup line in the tank, pretty much everything dealing with fuel, changed bulbs, changed some fuel lines bleed the system nothing but turn over and no start. even though there is no oil in the water and no water in the oil, I am thinking a blown head gasket, but I can not be sure of that, and the fact it did not get hot and shut it self down I am not sure. However I used it a few weeks before this incident and it lost power and started to blow white smoke out the tail pipe however I did manage to get it loaded on the trailer and get it home, and used it to unload the hay, but now it will not start. any ideas?

White smoke often occurs when there is either too much fuel being injected into the combustion chamber, or not enough heat to burn the fuel. Un-burned fuel travels through the exhaust system & exits out the tailpipe which will produce a scent of rich, un-burnt diesel.

 

[jp8775]

I purchased a 743 that had supposedly just started leaking antifreeze in the oil. It was the last straw for the guy and I got it for a song with a pile of new parts. He put a new radiator muffler and tons. So he changes the oil before I picked it up and he drove it up on my trailer. When I got it home there is no sign of coolant in the oil? I hate to take it apart for no reason but also hate to destroy the engine if it leaks. Is there a procedure to go through test for head or head gasket leaks that is mostly fool proof?

 

[tjc]

You more than likely have a cracked head.
Pull the radiator cap, fill full of water and look for bubbles.
Bottle feed the injection pump fuel with fuel to eliminate any fuel delivery issues.

I will try that and see what happens thanks

 

[North Idaho Wolfman]

I purchased a 743 that had supposedly just started leaking antifreeze in the oil. It was the last straw for the guy and I got it for a song with a pile of new parts. He put a new radiator muffler and tons. So he changes the oil before I picked it up and he drove it up on my trailer. When I got it home there is no sign of coolant in the oil? I hate to take it apart for no reason but also hate to destroy the engine if it leaks. Is there a procedure to go through test for head or head gasket leaks that is mostly fool proof?

You really should have started your own thread on this.

Pressure test the radiator, and pressure test the engine.

Use a radiator or coolant system pressure tester. if it doesn't hold 15lbs for 15 min then it's most likely leaking.

Pressure testing the engine is my choice, Remove the radiator cap before doing it, pull either the glow plugs or the injectors, spin the now free spinning motor and look for signs of moisture when it spins.
you can then inject air into the cylinder (100psi will more than do it), if you hear air out the intake or the exhaust, rotate the motor by hand till that quits (either direction is fine), if at any point air or coolant comes out the radiator, your done.

If you get air out the radiator, it's more likely to be a cracked head than it is a bad head gasket.
The cracks happen from a valve through to the pre chamber.

 

[tjc]

White smoke often occurs when there is either too much fuel being injected into the combustion chamber, or not enough heat to burn the fuel. Un-burned fuel travels through the exhaust system & exits out the tailpipe which will produce a scent of rich, un-burnt diesel.

Ok so if that's the case could a loose battery cable cause a lack of power enough to not allow it to run correctly

 

[North Idaho Wolfman]

Ok so if that's the case could a loose battery cable cause a lack of power enough to not allow it to run correctly

No, it's a 100% mechanically injected engine, you could pull the battery out of it and it would run, once started.
Electric has no bearing on it running properly, starting yes (glow plugs and starter operations).

 

[KJB1066]

Ok so if that's the case could a loose battery cable cause a lack of power enough to not allow it to run correctly

As Wolfman explained that the fuel system is mechanical. It seem you are on the most extreme problem.

Have you EVER used Starting fluid in the machine? Because Kubota engine have a close piston and combustion chamber tolerance and NEVER USE IT.

To do a little diagnostics on the machine will relieve a lot of stress. Buy a inexpensive cylinder compression tester or borrow one.

When you are trying to start the machine does it put out white smoke with strong odor of diesel? If so and if the compression test is good and you ohmed the glow plugs. see insert

Clean the glow plug and connector rail at connections and use Noalox or a dielectric grease you can find in the Electric aisle or Electrical supply house. Check for any frayed or broken wires. For good measure clean all electrical connection.

Check battery voltage and voltage at glow plugs also check voltage when cranking the engine. Buying a remote starter tool will help you greatly.

Good luck

 

[tjc]

I have never used starting fluid to start it, after sitting for the past 7 months and replacing the battery cables and a new battery all it will do is clunk like the starter is frozen, the starter was new 7 months ago before I let it set, so it is new as well. I will be pulling the starter when it gets nice again a few days from now, but I am still wondering if I did blow the head gasket. Is there a sure way of checking the head gasket before I take it apart?

 

[KJB1066]

I have never used starting fluid to start it, after sitting for the past 7 months and replacing the battery cables and a new battery all it will do is clunk like the starter is frozen, the starter was new 7 months ago before I let it set, so it is new as well. I will be pulling the starter when it gets nice again a few days from now, but I am still wondering if I did blow the head gasket. Is there a sure way of checking the head gasket before I take it apart?

Does the engine turn freely by hand?

Yes do a compression test the tool is not too expensive about $10 they are great to have. Another issue is looking for voltage drops if you have a short somewhere or not a good ground that will cause the clunking you hear. As I was taught just clean and tighten all connections. Do a bench test on the starter just get a remote starter tool and jump the solenoid. It's no fun getting that starter out.

 

[tjc]

Not sure about the engine turning freely that was my next thing to check. As far as the starter it is not fun taking it out or putting it back in, done it a few times I am on my 3rd starter over the past few years. I will pull it again bench test it and hope for the best, but not until the weather warms up again. it is still under warranty so if it is bad I can get another one. Thanks for the advice.