2015 HST glow plugs burning out

[imacky]

My 2015 HST had a problem with the glow plugs recently-- when trying to start it, the glow plug indicator lamp came on, but didn't go out in a few seconds like usual. Cranked it anyway but no start. I pulled the glow plugs to check them, and two read fine (about 1.3 ohms), but the back one was about 45 ohms, so obviously bad.

I replaced the bad one (NGK 3973 Y-724U about $20 each) and it was back to normal: glow plug light went out after a couple seconds and it fired right up.

A friend wanted to borrow the tractor, so I drove it over to his house and parked it, no problems. A couple days later when he went to start it, same symptoms-- glow plug indicator lit up but did not go out. He cranked it anyway, but no start. So I went over there and pulled the glow plugs to check them again, and this time all of them are bad. The new one read in the Kohms instead of 1.3 like before, and the other two original ones were in the Mohms.

So, they're all burned out now, including the new one

I've read about a timer that controls how long the glow plugs are heated, but it's obviously not just a timer since it also depends on the temperature. If it's cold, they need to be heated longer-- and if it's hot or the tractor was just in use, they might be heated for only a second or less.

I am guessing that despite the indicator light going out, there were heated the whole time I roaded it over to the friend's house and so they just burned out.

I don't have a wiring diagram or know how the glow plug circuit works, and I'm not going to install any more plugs until I'm sure the root problem is fixed.

Suggestions anyone?

There was one other thread about glow plugs on this tractor but I didn't find an answer there.

Thank you....

 

[the old grind]

The timer must have a relay somewhere. I suggest that the dashboard light might respond to the computer vs the timer's output or that relay from there to the plugs. What I mean is, and perhaps whether or not the timer is incorporated or "infused" (I love that one. :laughing in it or separate, IF it's relaying it's command to cluster, but might not not bi-directionally recognize that a relay sticks on.

If we can't reach or recognize particular wires, can we find a relay/fuse panel and swap relays to see if a fault follows it to another function. (starter, hazard, wiper, etc) We do it with cars nd trucks on the side of the road. It's not a call to AAA or a dealer when all that we have is in our pockets. Just thinking out of the bottle.

 

[AchingBack]

I hate to tell you, but break out your wallet. As was the case with my 2615, you need this upgrade. GLOW PLUG CONVERSION KIT FOR (EARLIER) 2015 MAHINDRA TRACTOR (19672980000)
I installed this several years ago, and the price was about $195. If you can buy just the timer, you might find the plugs much less expensive at an auto parts store.

My symptoms were the same, and my problem immediately went away.

 

[imacky]

Thanks both. I wasn't thinking about a relay, but if the relay is stuck that would explain it. The conversion kit AchingBack mentions does include a new relay since the new-style controller has an integrated one, but the kit comes with 3 glow plugs... which I already ordered. My friend's going to check if I have old or new style glow plug controls and let me know. If I have old-style I may just be able to replace the relay only (NGK G71SP?)

 

[imacky]

I have old-style (two box) controls. I talked it over with the friend and we're thinking I might end up frying 3 more glow plugs and a new relay, worst case... so I cancelled the 3 glow plugs and will with the conversion kit, that way everything's new.

 

[jgedmond]

There is an old thread about Mahindra glow plug problems that affected my 2011 3616. Basically, 12V feeds back to the glow plug controller from the fuel solenoid. This feeds voltage continuously to the glow plugs. The dash light just works off of the timer circuit=, not the voltage to the glow plugs, so the problem is not obvious.

If the new problem is similar to the old one, the fix is to install a diode (<$10 for a dozen solar cell diodes on Amazon) in the line from the fuel solenoid to prevent the voltage from back feeding. As suggested in the fix, I also installed a 12V LED between the glow plug rail and ground. That LED directly shows when the glow plugs are powered. For example, when you turn the key to on and the glow plug light comes on, so does my LED. However, after the glow plug light goes out, the LED flickers several times for a second or two. This is actually programmed into the glow plug controller to reduce smoking immediately after the engine starts.

Oh, and sparkplugs.com is a great resource for NGK glow plugs at great prices. Plugs for the 3616 there were $13 versus Mahindra's $82. I bought 3 new ones and 3 spares for less than 1 Mahindra glow plug, which of course is the same NGK plug!.

 

[imacky]

I like the 12V LED idea, I think I'll do that. And yes, I was ordering glow plugs from sparkplugs.com ($20 for NGK 3973 Y-724U), but the conversion kit comes with 3 plugs so no need this time.

 

[jaxs]

There is an old thread about Mahindra glow plug problems that affected my 2011 3616. Basically, 12V feeds back to the glow plug controller from the fuel solenoid. This feeds voltage continuously to the glow plugs. The dash light just works off of the timer circuit=, not the voltage to the glow plugs, so the problem is not obvious.

If the new problem is similar to the old one, the fix is to install a diode (<$10 for a dozen solar cell diodes on Amazon) in the line from the fuel solenoid to prevent the voltage from back feeding. As suggested in the fix, I also installed a 12V LED between the glow plug rail and ground. That LED directly shows when the glow plugs are powered. For example, when you turn the key to on and the glow plug light comes on, so does my LED. However, after the glow plug light goes out, the LED flickers several times for a second or two. This is actually programmed into the glow plug controller to reduce smoking immediately after the engine starts.

Oh, and sparkplugs.com is a great resource for NGK glow plugs at great prices. Plugs for the 3616 there were $13 versus Mahindra's $82. I bought 3 new ones and 3 spares for less than 1 Mahindra glow plug, which of course is the same NGK plug!.

Those are clever solutions.

 

[jgedmond]

I like the 12V LED idea, I think I'll do that. And yes, I was ordering glow plugs from sparkplugs.com ($20 for NGK 3973 Y-724U), but the conversion kit comes with 3 plugs so no need this time.

Actually, in your case, that is a very reasonable price for the Mahindra fix. In the case of my 3616, I was looking at about $200 for the controller and $82 each for 3 glow plugs or almost $450. Besides the cost, I went the way that I did because the actual root cause was never identified. I could be that there was a diode in the controller that failed and caused the back feeding. If so, having an external diode and an LED to detect back feeding would allow me to detect the problem and re-fix it cheaply and easily. Good luck in getting this resolved on your 2015.

 

[jgedmond]

Those are clever solutions.

Thanks, but I was just passing along one of the many things that I leaned from this great resource. Here is one of the threads on the 3016 / 3616 glow plug issue from 2017. There was one before that described the problem. In the 2017 thread, BillC72 provided a lot of details on how to implement the fix.

https://www.tractorbynet.com/forums...arting-glow.html?highlight=mahindra+glow+plug