2010 Diesel Glow Plug/Priming Questions

[Tigerhaze]

Hi guys-

I had a couple of questions about priming/starting the 2010 diesel engine. As the weather has been cooling off (70s), the engine has been getting progressively harder to start- to the point of excessive cranking. Once started and warm, it will fire up almost immediately. I have followed the glow plug procedure in the manual.

I really think that the glow plugs are not working. I have read the Operator's manual and looked over the service manual, and have a couple of questions. I am new to diesels so please bear with me.

-The service manual states that you check the glow plugs with an ammeter in series between the glow plug terminal and disconnected lead wire. Does the started switch need to be activated? Anything else I need to know about this check?
-It appears there is a serial number break of 29,000 for glow plugs- in absence of a serial number can you tell the difference between the two? It appears that the injector nozzle changes also coincide with the break- the older having a hold-down plate and the newer with a securing nut. Is this the correct way to differentiate?
-It appears that my crawler was converted from a generator to alternator and from 12V positive ground to 12V negative ground. Would that affect glow plug operation- I wouldn't think so?
-It appears the priming knob on my dash was removed at some point. How exactly does the knob prime the engine? Will that seriously affect cold starting ability?

Thanks for any help on the above questions- sorry about the length of them.

[Lavoy]

I think an easier way to test the glow plugs is with an ohm meter. Pull the wire to the glow plug, and test between the glow plug terminal and gound. If no resistance, no glow plug.
The later style glow plugs take a 3/8" or 7/16" wrench I believe and are about the size of a pencil give or take, the earlier glow plugs are bigger.
Primer shoots raw fuel into the intake manifold. They will start a little better with a primer, but the glow plugs are the critical item.
Polarity will not affect the glow plugs.
Lavoy

[Tigerhaze]

Thanks Lavoy.

[shinnery]

Lavoy

This is slightly off topic but what is the nominal resistance of a glow plug? I would think it would be about 10 ohms or less. When I see "no resistance" I think of a short, and infinite resistance for an open. But this is just my electronics background. I get tickled at so many times I hear someone talking about electrical problems as a short. Which would usually blow the fuses.
Bryce

[Lavoy]

I don't know the resistance, but it would be very high, I would think it would register as a short as far as an ohm meter is concerned. If they are shot, there would be no resistance (open?). I probably don't use the terms correctly, but I think you understand what I mean.
Lavoy

[wwattson]

Lavoy means that the resistance would be low and a normal glow plug resistance will look almost like a short. I don't know specifically what the Deere glow plugs run but I've seen everything from 10ths of ohms up to 10s of ohms over the range of ones I've measured on various diesels. I'd guess in this case that several ohms would be expected and open circuit or infinite resistance is bad.

[Tigerhaze]

Thanks for the insight- I will be checking them Saturday when I get back down there (my crawler is about an hour from where I am currently living). I can't afford to have hard starting once the weather cools a little more.

[Tigerhaze]

Well, I got to test my glow plugs yesterday. All four of them had a resistance of 3 ohms, so I am assuming that means they are all good. I did verify that I have the later early injection system with the banjo and retaining nut (between S/N 29000 and 42000).

The initial starting problem is still present. It starts right up once warmed and shut off, but is a bugger to start initially. It still seems like glow plugs aren't functioning, but being new to diesels I guess I don't know that for sure. I guess I'm looking for what to check next.

Is it common or likely for the start switch to become worn and cause the glow plugs from being energized when the key is turned? If so I may just replace the switch to see if it helps. I sort of wonder if maybe the starter isn't turning the engine over fast enough to cause combustion as well. I saw in another post that it made a difference for someone on their 1010. I guess the third potential issue may be that the engine compression is down, but once warm it has lots of power.

I hate eletrical problems- I am horrible at diagnosing them and am much better at dealing with mechanical problems.

Any ideas are appreciated.

[bighamlin]

I don't know about the 2010, but on the 1010 you got to hold the key to the left for 15 seconds to 3 minutes depending on temperature to run the glow plugs before starting. You may want to try taking them out, leaving the wire conected, and grounding them to make sure they are heating up. Even though the glow plugs may be good, make sure you are getting power to them. Good Luck.

Paul