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Hi all! Another question about my 2004 JD X495 diesel. It's winter here in Colorado and I keep the tractor in the garage to more easily clear snow when the time comes. But I have noticed that although the glo plug light comes on when I turn on the key and then goes out as if the glo plugs are warming up the tractor is very hard to start when its chilly. This tells me there is a possibility that although everything seems "normal" the glo plugs might not be getting the electrical to warm up. Anyone have any ideas on how to trouble shoot the issue OR just call the local dealer and pay his hourly rate to figure it out??? Thanks!
 

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AKA Moses Lawnagan
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Hi all! Another question about my 2004 JD X495 diesel. It's winter here in Colorado and I keep the tractor in the garage to more easily clear snow when the time comes. But I have noticed that although the glo plug light comes on when I turn on the key and then goes out as if the glo plugs are warming up the tractor is very hard to start when its chilly. This tells me there is a possibility that although everything seems "normal" the glo plugs might not be getting the electrical to warm up. Anyone have any ideas on how to trouble shoot the issue OR just call the local dealer and pay his hourly rate to figure it out??? Thanks!
By that, are you saying the glow plugs are warming up the electrical, or are you saying the plugs aren't getting the electricity need to heat up?

How many hours on the engine, and have the glow plugs ever been replaced? Have you tried cycling them a couple of times, and how cold is it outside when you're having trouble getting it to start? The plugs are designed to get hot enough to ignite the fuel being squirted by the injectors, when heat from compression is insufficient due to the cold-soaked block and cold intake air. As the plugs age, they need to be energized longer, and in the cold, battery voltage normally drops and may not heat the plugs to the degree needed. This is why you might try to cycle them a couple of times before turning the switch to 'start'. Run a load test on your battery (measure voltage while the plugs are heating) to make sure the battery is good, before you start replacing glow plugs, although they may need it if other methods fail to get the engine started. A cold diesel can be a bear to get started, and they need a strong battery to do it. If you find your battery marginal to start a cold engine, but it does okay otherwise, try hooking a battery charger to it using a high charge rate, while you try to start the engine.
 

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Grab a test light, put clamp on battery negative or engine block, touch prob on any on the three glow plugs and turn the key on and see if test light comes on along with glow plug light on dash.
Second test: remove wire off all three glow plugs, put test light clamp on battery positive post, touch pro on each glow plug, if light comes on glow plug good, no light, glow plug bad.


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Discussion Starter #4
Thanks. I will do these tests. The tractor was a donor by my brother in law in Alabama and I am sure the glo plugs have never been used. And that may be the problem.
I have a heated garage but I try not to heat it above about 40 or 50. Most of the time she starts fine but if I simply leave to garage door open for 30 minutes and the tractor is not running it won't start easily. The battery is new this past summer and is strong enough to start by just cranking for a long period. I will certainly do the electrical tests. BTW, what I am saying is it seems the glo plugs aren't heating as the battery and electrical seems strong.
 

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Another simple way to test glow plugs: Remove them one at a time and reconnect the electrical wire. Lay them one at a time on the engine block somewhere where they can be grounded. Cycle the switch and see if they heat up ----- they should heat up rapidly and they'll get red hot --- don't touch!!!

If they heat up, you're done. If they don't check voltage at the wire and check resistance of the glow plug. That should tell you if the glow plug is bad or if it's not getting voltage.
 

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Discussion Starter #6
So the glow plugs are at the ends of the "spark plug" wires and can be removed and then wires hooked back up?? I know enough to be dangerous. I know there are glow plugs but never knew where they were located. Thanks for this tip.
 

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They are easy to change and not that expensive. It should start immediately after the light goes out especially in a heated garage. On a 15 year old machine, I would just change them.
 

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Discussion Starter #8
OK, so here is what I did. I put my multimeter at the threaded end of the glow plug and on the engine block, turned on the key with the glow plug light lighted. 11 vdc on all three connections. this would tell me the electrical is getting through the relay to the glow plug and that possibly the glow pug is simply bad. It looks to replace them is simply an unbolt electrical and unscrew the plug, replace in kind. Sound right?
 

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Discussion Starter #11
anyone know where to find the engine Number? I know my tractor is X495 with Yanmar engine and I have the serial number but that isn't the Yanmar number.
 

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Discussion Starter #12
Got it. And bought the plugs from eBay. This site is wonderful for information and ways to solve problems. Thanks to all!
 

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be very carefull when removing glow plugs if the end is swollen they can be difficult to remove and possibly break off in cylinder,be very gentle when removing and be sure it's all there when removed,losing part of it means pulling head and it sounds like that's something you aren't familiar with. a simple way to check glow plugs for proper heating is with an amp draw test,just hold an inductance ammeter over each plug wire while cycling key,should be at least 7-8 amps ea.! I know my truck spec. draws 70 amps for 8 plugs.
 

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Discussion Starter #15
Very good point. I would have imagined that the plug would come out similar to a spark plug but if they are 16 years old and inoperable I can see where they might swell and break. The ammeter will tell the tale. Thanks for this.
 

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On my 6.2 GM diesel ,to test the glow plugs using a test light,you hook the test light to the positive battery terminal and unplug the glow plug to be tested,and touch the test light probe to the glow plug connector where the wire was hooked too--if it is still "working",the test light will light up..

However,I have had some test "good" that way,that were not heating up at all,or not getting hot enough,the most reliable "test" is to remove the glow plug as suggested above and clamp it in a jumper cable and connect the positive jumper to the battery + and ground the metal portion of the glow plug and see if it gets red hot,it should glow like an electric stove burner does after a few seconds..don't leave it on too long as they aren't supposed to stay on more than 5-10 seconds ,or they could overheat and fail,or swell up..

Since removing them is the best way to really see if they are working good,I usually just replace them,its enough work trying to get at them,and get them out of the cylinder head if they have swollen up--on my truck I've had to replace several sets due to the tabs on them where the wires connect,rotting away and breaking off when I go to unplug them,this is frustrating when it was a good one that did that,they are not cheap at $10 each--also had several have the hex portion rot away,making it a chore to get a socket on them that'll grip one well enough to unscrew them.
 

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Keep in mind your lawn mower does not have thousands of miles on northeast salt saturated roads on it. Ive replaced them on three of my yanmar diesels and yes use some care when loosening them, don't put a 3/4 in breaker bar on them, etc but they are an intended maintenance item like a spark plug.
 

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Discussion Starter #19
I just checked. Voltage but no amperage. Maybe instantaneous amperage but only a split second during initial key turn. After that, zero. Sounds like a glow plug change is in order. Emphasize careful glow plug change.
 

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How long is the glow plug lamp staying on?there is also a temp control {thermistor] in the circuit, if it's not reading correctly the plugs will short cycle or not cycle! I would remove the glow plugs first and get a visual on the condition! if they look good and no swelling, I'd start going after the electrical!
 
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