Community Forums

Kurt Averill · 01-08-2018, 09:45 PM

Can't help you on whether the build up is normal - though I'd think it would burn it off if they were working properly. Mine is a 10K so it has the Isuzu - so not quite the same - but very similar. The service manual does not give a value for resistance - just says to check for continuity to ground. Also notes to check for battery voltage at the glow plug while cranking.
I also noticed in your photo - NGK appears to be stamped into the base... you will probably find the base part number on the other side.

irishguy · 01-08-2018, 10:10 PM

Quote:

Originally Posted by Kurt Averill

Can't help you on whether the build up is normal - though I'd think it would burn it off if they were working properly. Mine is a 10K so it has the Isuzu - so not quite the same - but very similar. The service manual does not give a value for resistance - just says to check for continuity to ground. Also notes to check for battery voltage at the glow plug while cranking.
I also noticed in your photo - NGK appears to be stamped into the base... you will probably find the base part number on the other side.

I was looking at the part number but just can't make it out...going to try a magnifying glass. The NGK is sure visible though.

One way or another I'm putting in new ones...just a matter of how much I'm going to pay for them.

NHRA225 · 01-09-2018, 06:21 AM

Quote:

Originally Posted by irishguy

Here is a pic of one of my plugs. All three had fairly high resistance on my multi-meter ohm setting.

Note the black deposit on the glow end of the plug. Is that normal? Could it be from not working?

Looks Sooty- I would clean them and Test with a 12 volt battery- Should glow Red in 8 to 10 seconds, don't test any longer than 10 seconds.

RobRoy · 01-09-2018, 07:57 AM

I wouldn't be concerned about the soot on the glow plug....... go wipe your finger inside the tailpipe of your genny ....or the tail pipe of your coach and tell me what you see ...soot and lots of it

If you have continuity in all your glow plugs? ...... you may want looking elsewhere for your issue.

Perhaps test them as suggested and maybe even do so with them removed yet still hooked up in the circuit with ground wires attached each glow plug ...that would be very telling as to the integrity of the complete glow plug circuit.

Happy Hunting

rgvtexan · 01-09-2018, 07:59 AM

Quote:

Originally Posted by irishguy

What Kubota engine series do you have?

D722

YC1 · 01-09-2018, 10:31 AM

Crossing the bore and stroke of my 8KW generator to the factory service manual shows the engine to be a D722-B(E)

Do a search for D722 glow plugs and you will find tons of them around $20.

https://bestfarmparts.com/index.php?...SABEgK2ufD_BwE

oldguy70 · 01-09-2018, 04:48 PM

That's just a carbon build up. If they have continuity they should be find. Push your start
button and see if you have any voltage at the glow plugs. It could be as simple as a blown
fuse as somebody already measured. I live in Burnaby BC and there can be a huge savings getting parts on line from the States. I pick up my parts in Point Roberts Wa and there can be quite a savings in shipping.

YC1 · 01-09-2018, 05:11 PM

Factory spec shows .9 Ohms in my service manual. If you are seeing much higher they are sick.

irishguy · 01-09-2018, 06:54 PM

Hello All,

Well I ended up buying plugs at a local Kubota dealer. I had protested at the cost of them since as pointed by some of you, they are available online for around $20 per plug. Kubota said that they would drop their price from $90 per plug to $60 per plug. Cummins wanted $120 per plug! So I thought well I can get them now and install them, instead of ordering less expensive ones online and wait for delivery. I really wanted to exercise the generator today and charge up the batteries as we are getting a cold snap tonight with temps dropping to -20C for the next week.

My ohm meter showed high resistance on the old ones yesterday (off the scale). I still want to hook them up to a battery and see if they glow.

Anyway I put in the 3 new ones today with the outside temp right at freezing. The preheat only last about 3 seconds and it fired right up. That has never happened before in cold weather. It usually preheats for 15 seconds and then cranks continually.

Well needless to say I am quite happy!

In the future I'm going to check for parts on amazon, ebay etc.

The glow plug part number is NGK 1762 YEO1

Thank you all again for your help and guidance.

Irishguy

vito.a · 01-09-2018, 07:12 PM

Fantastic! I had the same results. Mine would crank and crank when cold but now after installing 3 new glow plugs it starts almost instantly.

For anyone with a 10k or 12.5k Onan, the NGK glow plugs are NGK 5392 Y720U. $10.96 from Rock Auto.

10Boomer · 01-09-2018, 09:14 PM

Quote:

Originally Posted by vito.a

Fantastic! I had the same results. Mine would crank and crank when cold but now after installing 3 new glow plugs it starts almost instantly.

For anyone with a 10k or 12.5k Onan, the NGK glow plugs are NGK 5392 Y720U. $10.96 from Rock Auto.

Part # for 8k gen. 2008 Onan.

RobRoy · 01-10-2018, 06:42 AM

Quote:

Originally Posted by irishguy

Hello All,

Well I ended up buying plugs at a local Kubota dealer. I had protested at the cost of them since as pointed by some of you, they are available online for around $20 per plug. Kubota said that they would drop their price from $90 per plug to $60 per plug. Cummins wanted $120 per plug! So I thought well I can get them now and install them, instead of ordering less expensive ones online and wait for delivery. I really wanted to exercise the generator today and charge up the batteries as we are getting a cold snap tonight with temps dropping to -20C for the next week.

My ohm meter showed high resistance on the old ones yesterday (off the scale). I still want to hook them up to a battery and see if they glow.

Anyway I put in the 3 new ones today with the outside temp right at freezing. The preheat only last about 3 seconds and it fired right up. That has never happened before in cold weather. It usually preheats for 15 seconds and then cranks continually.

Well needless to say I am quite happy!

In the future I'm going to check for parts on amazon, ebay etc.

The glow plug part number is NGK 1762 YEO1

Thank you all again for your help and guidance.

Irishguy

YC1 · 01-10-2018, 07:33 AM

Quote:

Originally Posted by 10Boomer

Part # for 8k gen. 2008 Onan.

Search for glow plugs for a D722 . You will find tons.

I crossed my engine bore and stroke in the service manual for the engine. Instead of using the Onan generator part to search with.

I found automotive stores have them and Amazon has plenty. Many are around $10 each.

98Dynasty · 01-12-2018, 02:18 PM

With all the valuable information that has been provided here I was able to repair my slow starting HDKAJ Onan QuietDiesel 7500 generator.
Here is what I have found.
Engine is Kubota D722.
Glow plugs part numbers are:
Onan 185-5421
NGK2649 (YE01)
Kumar Bros. KBEL102GP
Kubota 16851-65510

New glow plugs measure about 1.2 ohms.

Mine were original from 1998 and a little difficult to remove after they were unscrewed all the way with a 8MM deep well socket. Carbon buildup on the tips was excessive. Hope this information will help someone else. Total cost for me was $56.37 shipped from Kumar Bros. and I got them in 3 days.