Glow Plugs

[celdred]

Hey gang, I'm a proud new owner of a 1992 B7100 HST-D. I read a bunch of your threads before buying and then took delivery. Everything worked great for the first 2 weeks then I went out the other day and turned key to on, Glow Plug indicator light came on but the Controller coil wouldn't glow and thus she won't start. Am trying to figure out if it's a bad glow plug or a faulty controller. I've tested each plug with my Ohm meter and they are only reading .4 ohms which seems to be well within range. Battery is fully charged.

Does anyone have a fool proof way of testing Glow Plugs or the controller for that matter? I'd hate to buy 3 plugs, replace them all and find it's the controller. Neither part is returnable and my local dealer doesn't have the glow plugs in stock. They do have the $22 controller. Thanks for any help you can provide this first time diesel owner. Can't wait to get better aquainted with my new toy!

 

[George2615]

Glow plugs can be tested by unhooking the wire that goes to each and connecting an ohm meter from the center of the plug to ground. Can be done in block or removed. You should get resistance. It should not show a direct short nor an open circuit. I changed mine on a 3 year old tractor last year. 2 of 3 were bad. If yours check OK then it may be your timer control.

 

[RalphVa]

Glow plugs on my Benz lasted 23 years before a couple went out.

Ralph

 

[wushaw]

One other sure fire way to tell if glow plug is working is to remove it then hook it back up to wire and put glow plug in one hand and turn key with other....you'll know soon enough if that one works.

 

[RonMar]

One other sure fire way to tell if glow plug is working is to remove it then hook it back up to wire and put glow plug in one hand and turn key with other....you'll know soon enough if that one works.

Well most glow plugs get their circuit completed thru the engine block, so holding one in your hand with the hot wire connected would not be very eventfullas no current could flow thru it to heat it up

 

[KubotainNH]

The glow plug light on my B6100 never comes on anymore but they still work. I generally run for 30 secs when chilly and a minute when freezing. After that she starts right up. Don't be afraid to hold it on for awhile. I'd rather replace glow plugs than a starter. I've been using this method for a few years with no issues to the tractor. If it doesn't start right up then more glow plug time.

 

[Patches]

You can check the controller by switching your multi-meter to voltage; energize the controller and check for voltage at the glow-plug

 

[john_bud]

Hey gang, I'm a proud new owner of a 1992 B7100 HST-D. I read a bunch of your threads before buying and then took delivery. Everything worked great for the first 2 weeks then I went out the other day and turned key to on, Glow Plug indicator light came on but the Controller coil wouldn't glow and thus she won't start. Am trying to figure out if it's a bad glow plug or a faulty controller. I've tested each plug with my Ohm meter and they are only reading .4 ohms which seems to be well within range. Battery is fully charged.

Does anyone have a fool proof way of testing Glow Plugs or the controller for that matter? I'd hate to buy 3 plugs, replace them all and find it's the controller. Neither part is returnable and my local dealer doesn't have the glow plugs in stock. They do have the $22 controller. Thanks for any help you can provide this first time diesel owner. Can't wait to get better aquainted with my new toy!

0.4 ohms sounds about right to me too. Check the voltage when you activate them. The controller is probably the bad actor - but don't forget to check the fuse and the switch.

jb

 

[keo216]

Do you have to unhook the injector lines to change the glow plugs on a B7100?

 

[RalphVa]

No. No connection between glow plugs and injector lines unless they're in the way. Not likely.

 

[ericm979]

From memory the injectors are not in the way. If the injector lines are they can be removed easily.

 

[the old grind]

Does the 'controller' include a relay for GPs or just the timer and a relay is a separate thing to check. I suspect the light gets its power from the key-switch vs from the controller's output side.

You can check the controller by switching your multi-meter to voltage; energize the controller and check for voltage at the glow-plug

This ^^ is the very first thing I'd do. You start where power is dubious and work your way back toward the battery. Impedance check requires disconnecting each plug from the power bar. You knew that.

 

[keo216]

I keep asking a lot of questions about changing the glow plugs on a B7100 but I've never done it before and want to do it with the least effort possible.
Someone indicated I have to remove the intake manifold in order to change them. Is this right? ugh. I suppose there is a gasket involved that I have to replace. Not sure I even have the correct sockets or wrench to get them out.
By looking I've determined I'll have to remove some of the fuel lines running from the injector put to the injectors. Best to remove both ends I assume.

Has anyone seen a video or written article by someone that has done it. I'd sure love to find one if available. I've seen videos on how to test the glow plug after it's out but none actually removing them.
I get nervous about doing something like this when I've never done it before.
Thank the Lord it happened after the mowing season was over.
Any help is appreciated.

Additional Post: Nov 3rd, 2021 6:18 pm It's a 1996 Kubota B7100 HST with about 2300 hrs. Tractor has worked fine for yrs with no problems at all. Recently it has been a little hard to start but nothing that concerned me. And was rough right after starting but smoothed out within 30 sec. About 3 weeks ago I parked it in my shed and didn't try to start it for two weeks. When I did try to start it, it wouldn't fire a single time. I later in the day tried it again and still no firing. I did keep cranking it and after about 30 sec it did gradually start hitting and then started. I ran it for a few min then shut it off. Then tried to start it again and nothing. Not a single fire.
Well, I have replaced the glow plugs. The old ones tested good but replace them as I had them out anyway. When the key is turned to the left to warm up the plugs, the voltage to the plugs ranges from 9.5 to 10.9 V. Even when I turn the key to the right in the starting position they are getting almost the same voltage. I cracked the fuel line where it joins the injector and fuel is coming out. I'm not sure if that is a way to verify it's actually injecting into the cylinders but I have to assume it is. I'm stumped!!!!!! Anyone have any ideas.

 

[Texasmark]

Hey gang, I'm a proud new owner of a 1992 B7100 HST-D. I read a bunch of your threads before buying and then took delivery. Everything worked great for the first 2 weeks then I went out the other day and turned key to on, Glow Plug indicator light came on but the Controller coil wouldn't glow and thus she won't start. Am trying to figure out if it's a bad glow plug or a faulty controller. I've tested each plug with my Ohm meter and they are only reading .4 ohms which seems to be well within range. Battery is fully charged.

Does anyone have a fool proof way of testing Glow Plugs or the controller for that matter? I'd hate to buy 3 plugs, replace them all and find it's the controller. Neither part is returnable and my local dealer doesn't have the glow plugs in stock. They do have the $22 controller. Thanks for any help you can provide this first time diesel owner. Can't wait to get better aquainted with my new toy!

I'd get out your voltmeter and monitor the voltage applied to them if any during the preheat cycle. No voltage, not workie. Somewhere is a temp controller that probably has an ambient temperature monitor, or monitors something in the engine that is affected by the ambient temperature that allows voltage to the plugs. Colder the temp the longer the voltage is applied. Just because the dash light is on doesn't mean they are getting voltage. A service manual should have a wiring diagram and some have pictures where different things are located within the tractor.

 

[KubotainNH]

There's really not much to these, you turn the key all the way to the right to power the glow plugs, no sensors on these old steeds. As mentioned make sure you get battery power to the top of the 3 glow plugs. My B6100 had a loose connection that killed power to all the glow plugs. Also good to remove the wire and test resistance to ground on the glow plugs, they should all be about the same.

 

[SmallChange]

Well most glow plugs get their circuit completed thru the engine block, so holding one in your hand with the hot wire connected would not be very eventfullas no current could flow thru it to heat it up

They might find out even sooner this way, if they're standing in a puddle.