Searched and researched to death. Bought older kubota m4500dt. S2600 inline 6 diesel idi. Brand new injectors, 2 month old glow plugs, motor brand new rebuilt, less than 1 hour runtime. Cold starts inside insulated but unheated garage at around 32 degrees. Cycle plugs until resistor is cherry, turn to start. It starts but runs rough with lots of sputter and white smoke. I even try to cycle plugs back on to smooth out a little. It helps minor. Once warm up in about 5 minutes runs smooth as silk with great power. Resistor is inline like it should be, gp are almost brand new. I get around 11v when resistor is on at the plugs. Any ideas? Seems like in32 degrees it should run a little better even dead cold. Being brand new motor and injectors.
Gp, resistor or just plain cold?
- Thread starter Benjaminearl
- Start date
North Idaho Wolfman
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My kubota starts in single-digit F temps after a 90 second glow. (battery fully charged overnight) After a puff of black smoke, all three cylinders are firing.
Reading your description, several things come to mind:
*) There are different "glow plug indicators" based on which engine you have.
(the wrong one would reduce voltage to the GPs)
*) In cold weather, the instructions say to glow for 90 seconds or more. (IGNORE what the indicator is doing)
*) have you individually tested ALL six of your GPs? (From your description, it sounds as if at least one of them them is not heating up.)
TO TEST GPs -- No need to remove GPs from engine. Remove wire from the GP. Use ohmmeter to test from top of GP to engine-case. Expect very low ohms reading. (perhaps under 15 ohms) Also, expect all the GPs to be very close to same reading. If any GP measures vastly different than others, suspect it is bad.
Reading your description, several things come to mind:
*) There are different "glow plug indicators" based on which engine you have.
(the wrong one would reduce voltage to the GPs)
*) In cold weather, the instructions say to glow for 90 seconds or more. (IGNORE what the indicator is doing)
*) have you individually tested ALL six of your GPs? (From your description, it sounds as if at least one of them them is not heating up.)
TO TEST GPs -- No need to remove GPs from engine. Remove wire from the GP. Use ohmmeter to test from top of GP to engine-case. Expect very low ohms reading. (perhaps under 15 ohms) Also, expect all the GPs to be very close to same reading. If any GP measures vastly different than others, suspect it is bad.
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Have you checked your valve clearances since you bought the tractor? I worked on a lot of the Mercedes diesels and the first thing I checked when they had cold start issues were the valve clearances. On the 5 cylinder turbo diesels, the intake valves tightened up on them to zero clearance mainly because they were never set. If your engine has any tight valves, it will be hard starting in the cold.
Ok I started it again today. Cycled plugs. This time 9-9.5c at plugs. I think my resistor is going bad. So in turn I just held the switch longer than usual. Boom it fires always does. Still smoke,but running I turn the switch back on and it sounds like it's picking up cylinders when I do that.. With a few minutes it clears up. I think the rings really need to get set in. And a new resistor to help get a consistent glow. The plugs according to ngk are 10.5v. I wish I could bypass the resistor and just hold fora few seconds instead of half minute. Valve clearances are all good. Brand new motor by great rebuild shop. They put entire motor together.
Now seeing that it is a brand new engine, I'd say that it probably is not up to full compression and still a bit tight. Needs to be hooked to something and worked good for a few days. I would still recommend re-adjusting or at least checking the valve clearances AFTER you get 100-200 hours on the new engine. Ask the engine assembler for their recommendations.
So here is another question, With the new engine, did you take your starter apart and service it and re-lube everything? Makes a difference! Good, fast cranking speed is essential to a diesel to build heat in the cylinder to start good too. Unless the glow plugs are current limiting when they get hot, I wouldn't cycle them too long as I have seen them puff up from overheating in other IDI engines with glow plugs
RCW
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What engine oil does it have in it?
My little BX would run rough on cold starts with 15w-40 for a bit until things got moving freely ... maybe 10-30 seconds temperature dependent.
Much better with synthetic 5w-40.
Maybe the combination of fresh rebuild and heavy oil causing similar thing?
Certainly a long shot but worth considering.
Sent from my QTASUN1 using Tapatalk
My little BX would run rough on cold starts with 15w-40 for a bit until things got moving freely ... maybe 10-30 seconds temperature dependent.
Much better with synthetic 5w-40.
Maybe the combination of fresh rebuild and heavy oil causing similar thing?
Certainly a long shot but worth considering.
Sent from my QTASUN1 using Tapatalk
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Here's my experience.
I have a M4500 with 2400 hrs on the clock and in the summer it starts with the glow plugs but it's a clattery start. If I try to start it on the glow plugs alone below about 40F it takes about a 1-1.5 minutes of glow plug and even then it clatters to a ragged start. I think that's the nature of the beast.
If I use my block heater for 2 hrs below 40F and about 30-45 seconds of glow plug it fires right off and runs nicely.
You have a newly rebuilt engine and assuming it was assembled properly, it will be relatively tight. Is your starter and battery in good condition?
Most of those old tractors started like this and slobbered all over when they are cold! The new ones start and run better because of modern design and better control of the glow plugs. That said though, those old ones will still be running years from now while many of the new ones will be too expensive to repair!
I do not see where you answered NIW's question: Voltage at GP's while cranking.
Maybe I missed your answer.
I read the Owners' manual available on Kubotabooks.com. The wiring diagram is blurry and does not have a switch table showing what is powered in each switch position.
Often, it is important that the GP's continue to be powered while cranking and the ignition switch provides that connection.
Checking GP voltage while cranking would be prudent. A wrong ignition switch might not be sending power to the GP's when turned to the START position.
The manual says 40 seconds of GP when cold and further, below 5 F, 60 seconds.
Dave
Maybe I missed your answer.
I read the Owners' manual available on Kubotabooks.com. The wiring diagram is blurry and does not have a switch table showing what is powered in each switch position.
Often, it is important that the GP's continue to be powered while cranking and the ignition switch provides that connection.
Checking GP voltage while cranking would be prudent. A wrong ignition switch might not be sending power to the GP's when turned to the START position.
The manual says 40 seconds of GP when cold and further, below 5 F, 60 seconds.
Dave
Battery is brand new and almost 950cca. Starter turns it over nicely and fast. I guess I'm prolly just thinking it should start like a newer diesel. But I'm happy it starts better than my dad's ih574 with no cold start system at all. Oil I don't think is the problem. Engine shop says no way I'm broke in and up to full compression yet. I do think I need a few more volts to glow plugs though. But all in all I'm happy with the power of this inline 6. Block heater is next project on it.
Haven't measured it. Does glow while cranking and to be honest the resistor glows faster under crank. But the tractor really only cranks for a second or two before it takes off and chugs on its own
North Idaho Wolfman
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Something is wired wrong because the indicator should not glow when cranking.
Ok so now I need the part number for the indicator that gives output of 10.5v. I'm only getting 9-9.5. And even according to ngk that's not enough but Anything over 11 he says is too much as well. Any help with number or parts links is appreciated.
Wolfman's observation.
Needs checking.
Two, if all glow plugs are working correctly, and they should have 10.5V across them; the battery is at 12.5V, then the resistor should have 2V across it.
The resistor may not be the problem.
Bad connections will drop voltage. When the glowplugs are ON, the resistor terminal receiving battery voltage should be very close to battery voltage if there are good connections. Voltmeter from the battery positive post (not the lug) to the resistor, turn on the glowplugs, and you should see only maybe 0.1V.
Again, two things: correct wiring, and good connections. It may turn out to be the resistor, but the two things above need to be checked first.
85Hokie
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THAT is an old wives tale that needs to be put to bed.....
MOST major car/truck makers demand synthetic from the first start.
Diesels are no different.
that old saying .....the "rings will never seat" ......hog wash!
Viscosity = Viscosity...... a 5 in conventional is the same viscosity as 5 synthetic......
without getting on a whole another subject.....them thar synthetic molecules are just a little smaller and last a little longer!
North Idaho Wolfman
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I think you misunderstanding the system.
There is no resistor, there is a glow plug indicator, not the same thing.
Yes a bad glow plug indicator will drop the voltage, and too much if it's bad, has bad connections to it, or has bad wiring to and from it.
You say it glows when you crank it, so I know it's wired wrong, as it won't glow when cranked as the wiring bypasses the indicator on crank.
To determine if the glow plug controller is bad of if you have bad wiring or connections, measure the voltage at all these points.
With the switch in glow.
1A: At the battery
2A: Into the ignition switch
3A: Out of the ignition switch on the wire that goes to the in on indicator side of the glow indicator.
4A: At the out terminal on the glow indicator
5A: At the in to the glow plugs, at each one of the six.
With the switch in crank (remove the wire at the solenoid so it won't crank)
Indicator should not glow, if it does it's wired wrong, and you will need to fix that first.
1B: At the battery
2B: At the in on the ignition switch
3B: At the out of the second glow terminal, same as solenoid wire, that goes to the out of the glow indicator
4B: At the in to the glow plugs, at each of the six.
All of these measurements will tell you if you have a problem and where it is.
Tell us what measurements you get.
Glow Plug Indicator
P/N 15601-65950
There is no resistor, there is a glow plug indicator, not the same thing.
Yes a bad glow plug indicator will drop the voltage, and too much if it's bad, has bad connections to it, or has bad wiring to and from it.
You say it glows when you crank it, so I know it's wired wrong, as it won't glow when cranked as the wiring bypasses the indicator on crank.
To determine if the glow plug controller is bad of if you have bad wiring or connections, measure the voltage at all these points.
With the switch in glow.
1A: At the battery
2A: Into the ignition switch
3A: Out of the ignition switch on the wire that goes to the in on indicator side of the glow indicator.
4A: At the out terminal on the glow indicator
5A: At the in to the glow plugs, at each one of the six.
With the switch in crank (remove the wire at the solenoid so it won't crank)
Indicator should not glow, if it does it's wired wrong, and you will need to fix that first.
1B: At the battery
2B: At the in on the ignition switch
3B: At the out of the second glow terminal, same as solenoid wire, that goes to the out of the glow indicator
4B: At the in to the glow plugs, at each of the six.
All of these measurements will tell you if you have a problem and where it is.
Tell us what measurements you get.
Glow Plug Indicator
P/N 15601-65950
Correction it does not glow when cranking. I double checked. Gp all test good for ohns. 9.3 volts at gps and brand new fresh battery to boot. Indicator appears to work correctly and good connections. Just had whole tractor apart cleaned and wired.