Glow Relay Woe/Remedy

Magicman · June 22, 2012, 01:57:03 PM

During the last couple of jobs, my glow lamp has stayed on after the engine started. I would immediately turn the engine off and restart. I called WM yesterday and happened to get my favorite technician. He said "yup, that is the first indication that the electronics in the glow plug relay pack is failing". Sometimes it will reset such as mine did, but sometimes it would not. A new glow relay is $175.

OK, what is the alternative? He says, "how do you expect me to make a living if you do not buy parts".

Anyway, he suggested that I simply unplug the relay, get a switch and some wiring, and go with a manual glow. It was much simpler than that. The wiring was already there and laying idle in the wiring harness bundle.

First,I removed the relay cover and unplugged the glow relay.

Next, drill a 7/16" hole in the cover for the momentarily closed switch.

Cover the top of the relay receptacle with grease to protect it. Make a small pigtail to connect the switch to the glow fuse. Connect the idle blue wire to the other switch contact.

The other end of the blue wire connects to the starter solenoid as seen in the top left.

Now I can simply hold the switch for the desired glow interval. The switch was less than $7.00.

SPD748 · June 22, 2012, 02:05:47 PM

Excellent fix Magic! I have manual glow switches on several small diesel engines here. All have and continue to work perfectly. $7 beats $175 any day!

-lee

Cutting Edge · June 22, 2012, 02:12:22 PM

MM, I dunno how many amps are pulled when using your glow plugs, but its a good practice to use a starter solenoid on the supply & load cables and activate the solenoid itself that by the momentary switch. One for a lawn mower or 70's Ford truck work quite well. Seems those momentary switches soon fail (or worse) when hooked inline due to light duty contacts....fixed several for folks in the past. But you may already have that....but just an FIY/DIY for other folks.

Magicman · June 22, 2012, 02:47:41 PM

Yes, you are absolutely on the right track. The switch that I used is rated for 150 amps at 12VDC. The glow circuit is 80 amps.

If I had chosen to operate it from the console, then I would have used a starter relay which I already have. I then could have also used the ignition wire from the original glow circuit.

T Welsh · June 22, 2012, 04:01:57 PM

Good old Yankee ingenuity. Glad to hear you pushed off a new relay 8). Tim

woodmills1 · June 22, 2012, 07:59:38 PM

pretty sure majicman is not a yankee

I turn my key on and use a 7/8" wrench to complete the glow plug circuit on my 70...having already spent too much for a different fix.. I ama yankee

mine be all mechanical as far asa hookup ana I be da switch ansa counter

woodmills1 · June 22, 2012, 08:01:11 PM

shhh my 70 needs glow plugs ona day like today 97 degrees ???

Magicman · June 22, 2012, 08:35:35 PM

Quote from: T Welsh on June 22, 2012, 04:01:57 PM
Good old Yankee ingenuity. Tim

I have been called lotsa things, and most of them true, but generally my ingenuity is by necessity. Redneck ;D

flatrock58 · October 03, 2015, 11:24:35 AM

Magicman. I am having issues with my bosch relay on my kubota 42. I have to wiggle a wire going into the bottom of the relay to get the glow plugs to operate. I have tried to remove the relay but it does not want to come out and I didn't want to break it.

For some reason I thought that relay did more than just operate the glow plugs and could not be removed? I was planning on just leaving the relay in and putting a manual momentary switch in for the glow plugs. The replacement relay at WM says "

Relay, Diesel Glow Plug

Notes
Lombardini Glow Plug Relay 023359 replaces Bosch Relay 024598 to improve durability (LT30 Super Rev. H9.07, LT40 Super Rev. J1.07, LT30HD Super Rev. J5.07, LT40HD Super Rev. J5.08 and LT60HD/70HD Rev. A2.03). New relay requires manual operation of the glow plugs (See Form #1151)."

So I guess even if I get a replacement relay I would have to use a manual glow plug switch.

Where did you find a relay rated at 120 amps?

terrifictimbersllc · October 03, 2015, 05:08:18 PM

I have this updated relay, having replaced mine a couple years back, on my 2001 42HP Kubota. I think the "manual operation" refers to that relay does not automatically turn off the glow plugs after a certain interval of the key being turned to on, before turning it to start. It remains on for as long as the key is turned to on, before starting, then goes off after the engine is started. I do not have to make a separate manual connection to the glow plugs. That is what the relay does.

flatrock58 · October 03, 2015, 07:50:36 PM

terrifictimbersllc. Thanks for that information. That makes sense.
The other issue was the cost to replace the relay vs the cost to just put a manual switch in. The relay is $183.51. I am sure that a momentary switch would be a lot less and serve the same purpose.

terrifictimbersllc · October 03, 2015, 08:23:25 PM

I thought about that too but mine is front remote, that would be quite a few steps back and forth every time to start. I suppose if your controls are on the head and a button is right there it would be different. If yours is front remote spend the money and make it work right. p.s. I see you have extension so must be walk along.

flatrock58 · October 03, 2015, 08:36:09 PM

terrifictimbersllc Yes it is a walk along. I am a hobby sawyer for the moment so I try to keep cost down. If it were remote I would get the relay too.

How far is Mystic, Ct from Uncasville, Ct? My grandmother lived in Uncasville. We would spend a week up at her house every year. I do miss her and the fresh lobsters.

Magicman · October 03, 2015, 08:45:20 PM

Quote from: flatrock58 on October 03, 2015, 11:24:35 AMWhere did you find a relay rated at 120 amps?

I didn't, I used a manual switch. Thankfully the new Lombardini engine came with a new glow relay, etc. That is much better than holding a switch operated and counting.

flatrock58 · October 03, 2015, 09:47:47 PM

Magicman I meant where did you find a 120v switch. I have only seen 35v and 60v.

terrifictimbersllc · October 04, 2015, 03:12:48 AM

About 15 miles

Magicman · October 04, 2015, 08:15:12 AM

Quote from: flatrock58 on October 03, 2015, 09:47:47 PMMagicman I meant where did you find a 120v switch. I have only seen 35v and 60v.

I know that your v's above were meant to be a's. If you are finding 35a and 60a, switches, what voltage are they rated at?

Quote from: Magicman on June 22, 2012, 02:47:41 PMThe switch that I used is rated for 150 amps at 12VDC. The glow circuit is 80 amps.

Remember that "volts X amps = watts". The glow plug circuit above is 960 watts and the switch that I found was rated at 1800 watts. I found mine at my local electrical supply.

flatrock58 · October 04, 2015, 08:49:39 AM

Long day yesterday Magicman! I wrote that one fast and meant amps not volts. They were rated at 35 amps and 60 amps at 12 volts. I have seen larger starter switches rated higher and also could use a solenoid with a lower rated switch, but would rather just find a switch rated to higher amperage. Might try again to get take the relay out and see if I can clean it to fix the problem. It really did not want to just pull out when I tried before. Mine actually acts like it is an intermittent connection in the relax block . Winter is coming and I will need the glow plugs working.

Magicman · October 04, 2015, 08:57:59 AM

Chances are your relay may still be good and the problem is the socket where it plugs in. A bad contact there could cause what you are describing.

Since that 150 amp switch that I used was hard to press, I would lean toward a solenoid and low voltage switch on the console.

ncsawyer · October 04, 2015, 08:35:28 PM

My glow plugs did exactly like MM described his doing on my mill with about 35 hours on it. My relay gets a signal from the start circuit that tells it to turn the glow plugs off once the engine starts. My glow plugs would stay "on" for about 20 seconds after the engine started and then turn "off" by themselves, almost like they were on a timer. At the same time as the glow plug issue I noticed that my key switch started to act up and I would have to wiggle the key switch to get power through it. Replaced the key switch and it fixed the glow plug problem and the key switch problem.

Just FYI incase any of you guys run into the same symptoms.

flatrock58 · October 04, 2015, 08:40:48 PM

ncsawyer. Thanks for letting me know that. I will look at my switch and make sure it is not part of the problem.

bkaimwood · October 05, 2015, 06:42:06 AM

Nice fix MM, nice pics for guys like me who need picture books to follow along...my Kubota tractor was doing the same thing, but it was the ignition switch... Funny how most of the newer stuff needs glow plugs to live...my home made Isuzu diesel powered mill starts in 0 degree weather with no glow plugs...

Magicman · October 05, 2015, 08:51:23 AM

That Isuzu is a fine engine. Good compression and a battery/starter that spins the engine rather than turns it, is the key to good starts.

flatrock58 · October 05, 2015, 08:58:16 PM

Well I finally got the relay out and took it apart today. Looks like it needs some soldering. Off it goes to a friend of mine who is a retired Schlumberger electronic technician. He will be able to fix it. It is a little beyond my soldering abilities.