I have a kabota L4701 that will not start. I have fuel to the injectors, engine turns over as normal, all fuses and relays check to be good. I needing help to figure out what I am missing.
Kabota L4701 tractor will not start
- Thread starter Robert W. Duncan
- Start date
85Hokie
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Staff member
Lifetime Member
Equipment
BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Robert
Welcome to the forum - lets get a little more info on your KUBOTA .
Did it just NOT start one day?
Have you replaced anything?
Any evidence of mice or rodent in engine compartment?
Give us a little more history as to how it came to this point.
Welcome to the forum - lets get a little more info on your KUBOTA .
Did it just NOT start one day?
Have you replaced anything?
Any evidence of mice or rodent in engine compartment?
Give us a little more history as to how it came to this point.
I received this tractor from another one of our facilities. It has not ran for about 3 years. It supposedly got hot and they sent it to a mechanic that diagnosed it as having a bad engine. However when I received it, I could not find any evidence of how the mechanic came to that decision. I filled unit with coolant, cranked engine and found it to be blowing the coolant out of the radiator by just cranking the engine. It never started up at that time. I removed the head and only found the head bolts seemed to be out of torque tolerance. I inspected the cylinder bores and head but found nothing wrong. Cleaned up head, installed new head gasket and new bolts to specs. Adjusted valves and reassembled components. cranked engine, it has good compression, good fuel flow to injectors, does not push water out of radiator any more, but will not start up. I replaced relays, checked fuses, see no damage to wiring, sensor or safety switches. Not sure what I am missing. Tractor has only 1105 hours on it. HST transmission.
85Hokie
Moderator
Staff member
Lifetime Member
Equipment
BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
So...... the first mechanic thinks it over heated.
You verify that on the first start up by the coolant coming out of the radiator instantly.
To me - the head gasket/head/cylinder had to allow the compression to do that.
How did you "clean up the head?"
It had good compression - what was the PSI when you checked?
IF that engine overheated and warped the head ...... it might not show up instantly with a new gasket - since it has not got up to working temps.
Did you have the head inspected for any cracks? - was it dyed?
You verify that on the first start up by the coolant coming out of the radiator instantly.
To me - the head gasket/head/cylinder had to allow the compression to do that.
How did you "clean up the head?"
It had good compression - what was the PSI when you checked?
IF that engine overheated and warped the head ...... it might not show up instantly with a new gasket - since it has not got up to working temps.
Did you have the head inspected for any cracks? - was it dyed?
kubotafreak
Well-known member
Equipment
GRAND l6060, L3560, B6100, gr2100, tg 1860, g1800, g1900, g2160
Is there any smoke out the exhaust on cranking? (white, black, none) If you got coolant in the cylinders I bet you have
bent rods(low compression). You haven't posted numbers yet... unless you can confirm over 350psi dry/cold.
bent rods(low compression). You haven't posted numbers yet... unless you can confirm over 350psi dry/cold.
Last edited:
I have never heard of a KABOTA????
I have heard of-and worked on a KUBOTA, L4701HST.
I'll assume you have a Kubota L4701HST.
With that, what is your compression pressure as measured, at each cylinder?
in the dash where the hourmeter is. Does it show anything but hours when attempting to start? Example: P0336? Does it beep or anything?
I have heard of-and worked on a KUBOTA, L4701HST.
I'll assume you have a Kubota L4701HST.
With that, what is your compression pressure as measured, at each cylinder?
in the dash where the hourmeter is. Does it show anything but hours when attempting to start? Example: P0336? Does it beep or anything?
My bad. It is a Kubota.
I cleaned the head and engine block with brake clean and a 600 grit sand paper.
It only beeped when I was toggling thru the meter to view the codes.
It only had 2 codes, if I remember correctly the first code was for fuel rail pressure, PO193 and PO567, both were easy to remove manually from the meter panel, but I do not have a program to clear the ECM.
No smoke of any kind coming out of the exhaust.
I have not yet checked the compression.
I feel confident that I can listen to and engine and determine if it is getting enough compression to run. Also when setting the valves it had very good resistance when baring it over.
Only second Kubota for me to work on, so no I am not stating I know it all and do need help.
Because of not having a Kubota program to clear the codes, I replaced the ECM with another ECM, for the same exact model of tractor that was purchased at the same date and place of this one. But it made no change.
I cleaned the head and engine block with brake clean and a 600 grit sand paper.
It only beeped when I was toggling thru the meter to view the codes.
It only had 2 codes, if I remember correctly the first code was for fuel rail pressure, PO193 and PO567, both were easy to remove manually from the meter panel, but I do not have a program to clear the ECM.
No smoke of any kind coming out of the exhaust.
I have not yet checked the compression.
I feel confident that I can listen to and engine and determine if it is getting enough compression to run. Also when setting the valves it had very good resistance when baring it over.
Only second Kubota for me to work on, so no I am not stating I know it all and do need help.
Because of not having a Kubota program to clear the codes, I replaced the ECM with another ECM, for the same exact model of tractor that was purchased at the same date and place of this one. But it made no change.
As others have said do a compression test. confirm that you have fuel at the top of the injectors. Ohm each glow plug, confirm they're getting power.
Seems like I remember reading you have to program a bunch of parameters into a new ECM, matching it to injectors and dpf etc. Worth checking the wsm if you haven’t already. I am inclined to think you would be ahead hauling it in to dealer and his computer before spending more time on it.
Sheepfarmer is correct.
if you have rail pressure codes that needs to be addressed. Injectors can cause it. Supply pump can cause it. Filter can cause it. If for some reason the rail pressure went high, it damages the injectors and the rail pressure sensor and sometimes the supply pump. So if that's the case, you have to replace the fuel rail and send the injectors off for inspection and/or rebuild.
Injector rebuild is standard operating procedure anytime the engine is apart for repair anyway. They (engines) cost too much to play with used injectors.
Additionally while on that subject, you cannot just replace an ecu and expect it to work. It has to be programmed by dealer. The one you bought has a set of codes in it that identify each injector separately. You still have the same injectors, but the ecu expects to see whatever code it is programmed for. Also, the code is different on each injector (cylinder #1, 2, 3, 4, 5, 6 etc) and that code has to be properly programmed into the ecu for it to run properly on all kubota common rail engines. Failing to do this properly "can" lead to another engine failure. It will usually start & and run, just poorly if the injectors are swapped around and/or if the ecu's are swapped. It is also an emissions issue. Kubota calls it "injector compensation code". It cannot be changed by end user unless the end user has a working laptop loaded with licensed ($$$$$) kubota software and the correct adapters to make them all talk to each other. It's quite expensive even for the dealers to purchase. One of many reasons they have to charge what they do.
You won't get no smoke on a dpf equipped engine at all. The filter catches the fuel that would normally show up while cranking.
if you have rail pressure codes that needs to be addressed. Injectors can cause it. Supply pump can cause it. Filter can cause it. If for some reason the rail pressure went high, it damages the injectors and the rail pressure sensor and sometimes the supply pump. So if that's the case, you have to replace the fuel rail and send the injectors off for inspection and/or rebuild.
Injector rebuild is standard operating procedure anytime the engine is apart for repair anyway. They (engines) cost too much to play with used injectors.
Additionally while on that subject, you cannot just replace an ecu and expect it to work. It has to be programmed by dealer. The one you bought has a set of codes in it that identify each injector separately. You still have the same injectors, but the ecu expects to see whatever code it is programmed for. Also, the code is different on each injector (cylinder #1, 2, 3, 4, 5, 6 etc) and that code has to be properly programmed into the ecu for it to run properly on all kubota common rail engines. Failing to do this properly "can" lead to another engine failure. It will usually start & and run, just poorly if the injectors are swapped around and/or if the ecu's are swapped. It is also an emissions issue. Kubota calls it "injector compensation code". It cannot be changed by end user unless the end user has a working laptop loaded with licensed ($$$$$) kubota software and the correct adapters to make them all talk to each other. It's quite expensive even for the dealers to purchase. One of many reasons they have to charge what they do.
You won't get no smoke on a dpf equipped engine at all. The filter catches the fuel that would normally show up while cranking.