kubota glow plug indicator not glowing/hard cold start

[stubbornrichard]

For some reason when i preheat, it dosn't glow but the glow plugs get warm but in no way hot as they should be, first i thought the connections so i cleaned all of them and same problem, the little coil does not glow even if i preheat for 40 seconds, it still takes about 3 tries to start the thing, i know its below freezing but i can't remember it ever being this hard. my fear is that the glow plugs are damaged (previous owner used starting fluid...ALOT), my other thought was the coil could need replacing. but these are just ideas, thanks for any help

 

[paulyny]

Ive been thru that before several times. If youve got meter start checking voltage. Start with the battery. Check the glow plugs for continuinity. I believe you should be getting 10.5v at the plug. Could also be the key switch too. Before you rip anything apart start poking around with a cheap multimeter. Worst case scenario in my opinion could be bad plugs. Maybe bad or dirty connections,bad ground etc.. Tractorsmart is who i use for my plugs. If you search old posts in the meantime you will get tons of info on the subject. Post back here with any results. What model Kubota is it?

 

[art]

It would be nice to know which model we are working with. I would take a guess that they haven't been right for a while.

With the thought that he could use either he had given up. I can't think of any Kubota engines that don't start when it is well below freezing on there own if the glow plugs are working.

You might also be fighting a loss in compression from the either if the use was as great as you say after you get them fixed.

 

[paulyny]

I bought a B8200 from a fellow that had trouble starting this machine for years. He drilled a hole in the air intake hose and glued in a 3/8 plastic tubing to spray ether into when he wanted to start it. It was hard starting and pre heat didnt work either. I simply changed the glow plugs and machine works as it should. Im still using it today. Dont use ether on a diesel!

 

[stubbornrichard]

Thanks for the ideas guys yea i was going to check them with a multimeter today, i had this problem with my other kubota the b7100 it turned out to be dirty connections but this problem is on my welding machine, it's a v1902 series motor, i shure hope the compression is good but once it starts it runs smoother than anything else i have and there is no smoke coming out of the stack just heat waves, i have a mobile welding buisness and use it every day so i have been letting this small problem go but now that its the winter it's really getting to be a problem, parts are easy to get for the engine but for some reason its hard to find specs on it, the dealer just told me "well its a good one" but had no idea on the output or other specs that i was obviously very curious about

 

[stubbornrichard]

Ok so i just came in from the engine, when i got out there i realized that i forgot how to properly use a multimeter so i put it on the 1k ohm and put the negative on the base of the plug and the positive on the little pointy tip and the dial sweeped across, this probably means nothing, so i thought i would ask how to properly set the meter and where to place the pins on the plug, but i did find out buy using the 1k ohm position that all the plugs are getting a connection, the good news is if i need new plugs they only cost about 56 bucks each i thought that they were over $100 each

 

[Lefty_Kubota]

are you checking the resistance with the glow plugs in or out of the engine?

 

[stubbornrichard]

i just checked them when they were still in the machine, the meter has a 15volt or 150 volt setting and i put it on the 15 volt one and when i hit the preheat switch the needle swept across like when it was on the ohms setting, so im guessing this means there getting power but its not really telling me if there properly working

 

[PILOON]

To properly check a glow plug (it is basically a resistor) you want to disconnect the wire to each one.

Select the lowest resistance scale on the meter (like 100 ohms) and read resistance from plug lug to engine block.

REading should be VERY low ohms (like under 50, and as low as 10).
If a reading on each-then OK.

If no ohms- then plug is open/burnt out.

Reading 12 volts at plug terminal is only indicating that power is getting there!

 

[Ford850]

Stubborn,
I pulled this from the Tractorsmart site:
"Other causes include defective glow plugs or low cranking speeds from a weak battery. The best way to check glow plugs is to yank 'em out and hook 'em to a battery (ground on the body, positive on the connection end.) If they glow red, they're OK. (Watch that you don't burn yourself!) Another problem with glow plugs is found in the connection wires between the plugs. These connections tend to corrode over time (just like battery cables). Clean them with some sandpaper before reinstalling to the glow plugs. If you don't want to test your glow plugs before replacing them, can I have your old ones? Glow plugs rarely go bad folks."

 

[SnowRidge]

For some reason when i preheat, it dosn't glow but the glow plugs get warm but in no way hot as they should be, first i thought the connections so i cleaned all of them and same problem, the little coil does not glow even if i preheat for 40 seconds, it still takes about 3 tries to start the thing, i know its below freezing but i can't remember it ever being this hard. my fear is that the glow plugs are damaged (previous owner used starting fluid...ALOT), my other thought was the coil could need replacing. but these are just ideas, thanks for any help

Is this machine new to you, and have you ever started it under the current conditions and had it do other than what it is doing now? How are you determining the glow plugs are warm, not hot? There is no way to tell with the plugs in the engine, as the head sinks all of the heat they produce before you could feel it on the plug body with your fingers, if that is what you are doing.

It is not that uncommon to not be able to see an indicator coil glow in the daytime, even though it is conducting. You could try a new one and see if that helps. The old one may have aged enough that it does not conduct as well as it should.

Glow plugs on engines with indicator coils are usually wired so that the plugs are in parallel with each other, but in series with the indicator coil. The only failed component other that the switch that would result in no glow plug activity at all would be the indicator coil. However, I have seen one Kubota wiring diagram that showed the plugs in series with each other, a resistor, and the coil. That kind of lash up would result in no glow plug activity if any of the components failed.

As has already been posted, glow plugs almost never fail. Difficult starting in below freezing weather is not all that unusual for diesels, especially if their compression is down a little bit. That may be what is going on.

 

[stubbornrichard]

i just put my finger on the first one and found it extremely hot and the other three nothing really at all, i just figured that ment they were not getting hot, i have had the machine for about 7 years and never had a problem like this even in colder weather it always fired right up first try, i like the idea of disconnecting the wires and checking for resistance like PILOON said and if that fails ill take them out and mabe try hooking them to a battery

 

[stubbornrichard]

i think i will have to buy a better multimeter though mine only has 1k ohm for resistance setting all the rest are volt settings

 

[SnowRidge]

i just put my finger on the first one and found it extremely hot and the other three nothing really at all, i just figured that ment they were not getting hot, i have had the machine for about 7 years and never had a problem like this even in colder weather it always fired right up first try, i like the idea of disconnecting the wires and checking for resistance like PILOON said and if that fails ill take them out and mabe try hooking them to a battery

Out of curiosity, I tried that on my Branson and could not tell any difference between power on and off. The machine had not been run all day, at the time.

I wonder if you have one with a short. That would be extremely rare, but it might account for what you are seeing, although I certainly would expect the indicator coil to glow under those circumstances.

Be careful about hooking them directly to a battery. The indicator coil acts as a resistor. Without it in the circuit, you might burn one out. If you do hook one directly to a battery, do it very briefly.

 

[stubbornrichard]

Im with you on that one Snow, i was reading about that acting as a resistor and some people say 8 or so seconds maximum but with those close clearences i dont want to take any chances, i just might end up taking them to get checked at the kubota dealer if im still in confusion the next few days but i think im going to have to take them out no matter what wich is easy for the first 3 plugs but the last one is right behind the injector pump area and all of the steel lines

 

[PILOON]

The glow plugs AND the indicator are all 'in parallel'.

One side is positive and other ground, the engine being the ground.
That being said, one side of the indicator is ground and the other positive.

In that way the plugs AND the indicator all heat (glow) at the same time.
(glow plugs, get it!)

The indicator is sort of 'an out of body' glow plug.

In parallel circuit they all get the same voltage at the same time and if one is burnt the others still work.

Series, one goes, none 'glow'!

Glow plugs being high amperage devices by nature are more suseptable to bad connections, so clean all contacts.

 

[banjodunn]

quickest and easiest way to check is to whip them out connect up to a battery for no more than 5 secs they should glow red hot in that time if not get new ones we commonly find over here that once one is gone that the rest are not far behind YES they do burn out they work on a dead short so they do have a limited life, please be careful doing this though as i have seen holes burnt in batteries

 

[al b]

I checked mine by taking them out and using the wire that goes to the first one and then grounding the plug to the block turned the key and turned the switch to glow and it turned red. Did the same to the others. They all got red hot so I put them back. But my Kubota still starts hard so now I'm thinking I'll check the valve gap. If the valve gap is too big and the valves aren't opening long enough won't it effect the compression? I don't have a compression Gage or I'd check it. Maybe that's our problem.

 

[stubbornrichard]

I also was thinking about compression but i always just thought that if it didnt smoke when running i was fine (just a very rough estimate), during any warmer seasons it starts up just fine its just this cold weather it does it in, but i have some good news about the glow plug prices, i went down to the local autoparts store and i can buy plugs there for $13,95 each so obviously the dealer price at almost $60 each was typical dealer prices, or i was quoted for actual kubota brand plugs but i doubt they make there own

 

[al b]

Mine is the same way. When it is warm it starts right up, now that is is cold it starts really hard. Bought a new battery,new air filter put synthetic oil, glow plugs work good. I haven't found the problem yet. If the valves are ok the next is going to be a compression test. I suppose if all cylinders had low compression it could run and it would run smooth it would just be hard to get going.