I have had 6 glow plugs go bad in under a year and some of them twice in my new l5p.
also just developed a coolant link in the front passenger side. About to rip into this thing any one have any input on what/where these issues could be.
2017 gmc sierra 3500hd drw 50k no mods

Leak now link

 

Woah.. I had that on our 2012 2500LML.. they warranted the GP longer because it was their issue and they owned up to it. For a LOT of the LMLs.

What a huge pain to have the truck down when you are depending on it.

The GP would fail in “startup”... always when I would get in truck when cold and quickly spin to crank it. I firmly believe it was the BCM for the GP that caused over current to the GP during the initial start sequence from the ignition key turn. In fact, when I told the GM Rep my thought on the cause, he actually stammered.. started blinking his eyes... I thought for the moment he might be ill... nope, busted. At least regarding my truck. I am sure I am the only one to have considered...

There may be other causes... sure, but for it to be so specific, and other possibilities eliminated, well, “It is elementary, Watson.” I forget who said it.. “When you have eliminated every possible cause and reason, whatever remains, no matter how impossible or improbable, must be true.”

the truck had other issues.. the driver seat cooling fan Module self destructed... the collision features, airbag, steering wheel and side pillars, other emission problems as widely experienced and stated .. burned thru DEF like .. well, a lot...

On one occasion DEF used up100 miles from limp mode in a little over a tank of fuel. (Got fuel at a mom-pop store up in Arkansas back water... ) and it had “that smell” of different fuel. A couple tanks later the fuel filter was done. Not GMs fault there.

But it pulled very well... until abandoning us several times, states away from home with GPs and NOX sensor failures..

It became a good “farmers truck” and is happily rolling out the rest of its life after being neutered (deleted) and no longer licensed for the road. Or so I hear...

 

I have had 3 glow plugs replaced in 93K miles.

 

L5P glow plugs have a learn procedure that has to be done if one is replaced..

The glow plugs are controlled by the GPCM and the ECM..

We have replaced 2 engines for the tips breaking off when removing..

Remove them while the engine is still warm..

 

L5P glow plugs have a learn procedure that has to be done if one is replaced..

The glow plugs are controlled by the GPCM and the ECM..

We have replaced 2 engines for the tips breaking off when removing..

Remove them while the engine is still warm..

how common is it with the 2019's to loose glow plugs and even injectors.. seems like lots of folks have posted about this...

seems like 'many' of the injector replacements might have been the connector and not the actual injector that had gone bad..

but this glow plug issue seems to come in waves...

 

A friend of mine has a 2017 with less than 50k miles and has gone through several glow plugs and injectors. He’s also had the head gaskets replaced twice with second round needing new heads and turbo. The second time his truck went down it started by blowing the coolant line.

I’ve experienced low coolant light 4 times in 72k miles with coolant tank still being full. I don’t doubt issues with loose connectors and only question if head gaskets aren’t allowing pressure to get into cooling system and cylinders.


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A friend of mine has a 2017 with less than 50k miles and has gone through several glow plugs and injectors. He’s also had the head gaskets replaced twice with second round needing new heads and turbo. The second time his truck went down it started by blowing the coolant line.

I’ve experienced low coolant light 4 times in 72k miles with coolant tank still being full. I don’t doubt issues with loose connectors and only question if head gaskets aren’t allowing pressure to get into cooling system and cylinders.


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I am in that boat with coolant warnings..

bought this '19 last fall 15k miles on it. CPO inspection done they day I picked it up
. first weekend I had it.. low coolant warning.. and yes. the coolant was low.. at the seam

took it in... and they topped it up..said system was down didnt get a worksheet.. ie it wasn't logged

a couple weeks later.. it was getting low again.. no warning yet but it was at the bottom of the arrows.. took it in again.. with the TSB and asked that the system be checked for leaks at all the spots (i doubt they removed the alternator to check the EGR flange) and to VAC-N-Fil multiple times per the TSB but was not keen on the 3000rpm in a service bay for 10 minutes to check for head gaskets.. the service manager and diesel tech said that based on how the truck was running .. didnt sound like head gaskets either.. and the block heater recall was done a couple thousand miles prior.. they though bad burping...

coolant levels mostly held for the last 2k miles or so.. then out of nowhere coolant warning with tank full...

they replaced the tank... with new caps.. and right out of the gate.. the next morning cold.. coolant settled at the arrow heads.. and after 3 drive cycles remains at the full mark without needing a top off..

keeping finger crossed.. my upper hose is firm HOT but very soft next morning .. so I really dont see head gaskets.. have not towed with it yet so its not really getting worked..

odd thing with the old tank.. I had it filled where it was holding its level say half way between the top of arrows and the neck.. and held there for several road trips..

took it to dealer that did alignment and idled it for about 40 minutes while doing it I guess and when I picked it up.. the next morning it settled at the arrows so lost some... so either they drove it like a drunk teenager again and managed to get head gasket to lift/blow by.. or there is a small leak in the EGR when it gets really hot.. just dont know..

the iron around the turbo and the bolts on the turbo shield are really rusty and the turbo controller aluminum housing is getting powdery like there is moisture there all the time.. but see no evidence of coolant leak and they put visible dye in sever months back....

really a head scratcher.. hoping this new tank fixes it.. perhaps the old tank had a small crack or a bad cap....

 

Just for grins...

my first 2509, 2012 year needed a top off twice. Both after significant weather temp drop. Held for 4 years.
Our 2017 was on the money until the block heater update done. Now the fluid shows almost too low, to completely full.

I have no clue where the stuff is moving to. Is it a hose stretching, voids burping out air then refilling later as the coolant whizzes by?

would like an old school “sight glass” in the coolant stream... anyone here a patent attorney?

 

I didnt own the truck during the heater TSB.. but I believe I have seen the aftermath...

the L5P is very hard to burp.. there are now at least 2 possibly 3 TSB that deal with L5P coolant issues...

one tells the lot boy how to top up new trucks because they cant get it right at the factory on brand new trucks

another explains to techs where to look for typical leaks.. there are multiple places where manufacturing or assembly defects are known to hide.. several ERG pipe welds, a rolled EGR pipe o ring... and there is even a TSB about checking the L5P for doubled up head gaskets by looking at the external tabs... that on occasion 2 gaskets by be installed on one or both side... nice.. no extra charge for the extra part...

the top cap on the L5P is threaded backward righty/loosy and I am sure there is at least one lot boy that could not read the ideogram on top with the twist arrow.. and the TSB states that trying to turn the cap the wrong way my cause issues.. like break it.. not work correctly..

if air is left in the system.. those voids turn to steam which of course expands and contracts more than coolant itself. so as that void area pushes more coolant into the overflow (bottom) part of the tank.. it off boards into the wheel well area .. and you loose even more coolant... just as an aside.. the L5P has 2 ports that VENT coolant.. everyone looks at the top hose..that only vents if you try and open the cap while its under pressure.. but if the system sees pressure above 20 psi .. the pressure cap which is on the fender side at the bottom of the tank has a nipple and it vent right into the tray under the coolant bottle.. its nearly impossible to see.. and the coolant from both ends up in the same place.. passenger wheel well / frame

the only proper way to fill these engines is with a Vac-N-Fil device connected to a NEW adapter cap that fits on the tank.. the tank adapter tool costs over 100 bucks and I am sure there is at least some techs / dealers that didnt have the right one... let alone the vac-n-fil tool

so they just think the top and go works.. which it won't...

once the caps have pissed fluid enough times with hot coolant they won't hold pressure correctly any more as it weakens the pressure relief springs...

so far after 2 drive cycles.. the new tank is working good.. and levels are at the top of the arrows.. even at temps below 70... its been more like 40..

with the old tank even after several VAC fills and them driving the crap out of it.. it still needed to be topped a couple times after I got it back.. so I think my old tank had issues...

it COULD still be a head gasket or EGR (internal or external) leak.. but only time will tell.. if I have issues one more time I will have to have them do the proceedure to run the engine to 3000 rpm for 10 minutes in a stall with the pressure gauge on the coolant tank looking for high pressure readings per the TSB

they will do that before doing a compression test because if they pull the glow plugs to test compression they have to replace them.. one time use only.. so that costs them money... floating our heads in a stall abusing our engines cost them nothing

 

Odd now that u mentioned a coolant issue my 17 is also leaking coolant from the front passenger side........ i assumed it was from the drain. I need to check again.

 

I know this is a late reply, but this might help someone.
On my 17' at about 72000 miles, I started burning through 1,3,5 & 7 glow plugs (not all at once, but intermittently over a 4 month period). After several replacements and having them diagnose the controller several times, I finally convinced them to check it while it was running. Result: Glow plug controller was sending a signal to 1,3,5&7 glow plugs even after engine was started and warm. Replacement was still covered under warranty because it is part of the 100000 coverage. Looking back I do remember one day I started it, it missed and after that time the glow plugs started to go on the passenger side only. If anyone is burning through plugs, have them check the controller while the truck is running to see if it is sending a signal. No code was thrown for the controller (just several for the glow plugs-and these would sometimes clear themselves like the problem was resolved only to come back) and for all they could tell everything was fine with the controller.\
No problems since replacement.

 

I know this is a late reply, but this might help someone.
On my 17' at about 72000 miles, I started burning through 1,3,5 & 7 glow plugs (not all at once, but intermittently over a 4 month period). After several replacements and having them diagnose the controller several times, I finally convinced them to check it while it was running. Result: Glow plug controller was sending a signal to 1,3,5&7 glow plugs even after engine was started and warm. Replacement was still covered under warranty because it is part of the 100000 coverage. Looking back I do remember one day I started it, it missed and after that time the glow plugs started to go on the passenger side only. If anyone is burning through plugs, have them check the controller while the truck is running to see if it is sending a signal. No code was thrown for the controller (just several for the glow plugs-and these would sometimes clear themselves like the problem was resolved only to come back) and for all they could tell everything was fine with the controller.\
No problems since replacement.

I currently have 39,000 on my 2017, and it just started with the check engine light and all the dealership would tell me is that it was a glow plug code. Nothing else. I'm under the impression that it is a bad glow plug at this point, but they wouldn't tell me more until a "service tech took a closer look at it". I don't get a warm fuzzy from the service advisors at my local GM dealership (Countryside). They never like to tell you the whole story and don't even hide the fact that they aren't willing to tell you everything you should know to make an educated decision. Interested in learning more about what you did to have the glow plugs covered under the 100k coverage and if anyone else can tell me what to expect to pay for this repair otherwise....

 

The glow plugs on the '17-'19 should be covered for 10 years 150k miles. My 2018 is and they sent me a letter stating the extended warranty details.

 

I just talked with my local dealer and they say the truck is covered 5 years, 100,000 miles. No mention of extended warranty.

 

I told the dealer and rep 8 years ago that’s the controller was the problem…. Long explanation but if you start “losing” GP’s replace controller.

must note, if you “crank” the engine cold you will almost always see the problem start. Especially with marginal batteries because the voltage drop flows too many amps… poof.

So, I try to turn key on until gauges zero, check voltage then crank.

It won’t be under warranty forever.

 

cfell makes a very good point! Basic electrical theory states that the lower the voltage, the higher the amperage a device will pull! With a glow plug, its basically a coil that shorts from hot to ground to create heat, and you have 6 or 8 of them all going at the same time, that's a lot of current its pulling! From 13 volts down to 11 volts, a load of 15 amps will jump to over 19A with just the drop of 2 volts. The glow plugs aren't designed to handle extended high-amperage loads and thus will damage them over time.

 

My letter just mentions my 19. 15 years or 150k miles.

 

 

Interesting letter, thanks for posting. I wonder if this is a result of this problem found in 17's, however I received no such letter, but perhaps because repairs were already made. Focus is mostly made on the newer trucks anyway, unless of course there is enough evidence for a recall. This letter tells me, there is enough evidence that was tangible to release a letter to a focused (small) group, but not on a level of recall.

 

Not much info was posted at Techlink. Glow Plug Control Module Software Update – TechLink

 

I have had 6 glow plugs go bad in under a year and some of them twice in my new l5p.
also just developed a coolant link in the front passenger side. About to rip into this thing any one have any input on what/where these issues could be.
2017 gmc sierra 3500hd drw 50k no mods

Have your batteries load tested. Remove them one at a time to do it right.

There is a correlation to batteries going bad and GP failures. The lower voltage causes a higher Amp draw to get the needed Watts. HIgher Amps = higher heat = burned GP filaments!

 

i had 3 glow plugs go on my 19 chevy 3500 DRW LT all within 30000-34000 Miles

 

See attachment.

 

ON MY 2017, I'm sure it's been 5 times bring it in for glow plug faults. They warranty just the one that failed. A month or two later another one. etc. It's frustrating. I wish they would just change all of them under warranty.

 

Your truck is 6 years old, Im, guessing your batteries are 6 years old as well. There seems to be a correlation between weak batteries and GP failures. The lower voltage causes higher amps and the resulting additional heat burns out the GP.

Have your batteries load tested to see if they are nearing the end of their life. If even one is not good, replace them both, After that your GP issues will most likely vanish along with the old batteries.

Also, with the old batteries wait until the GP light extinguishes before starting the engine. The draw from the GPs and the starter will combine to draw evenmore amps resulting in even higher temps for the GP resulting n a failure.

 

Okay, ill get the batteries tested and see. I was not aware that weak batteries could be a contributor. I always wait til the glow plug lights are off before starting, plus its always plugged in -5C and below. Thanks I will let you know the outcome when I get a chance

 

Interesting, is this going on on just one side of the engine (this was the case on mine, only passenger side (odd->1,3,5,7 plugs were going))? You could have them test the GPM to see if it is sending signals while the vehicle is running. This was my issue. Took a while for us to figure out. They were burning up because the controller was sending signals after starting the vehicle (bad controller) The replacement will be covered, but if they try to reprogram first, that typically will not be covered.

I agree with @407driver about the batteries, so check those first. However, if the controller is bad already, it likely will not make a difference. You still need good batteries though to prevent future problems.

 

Ive had GPs fail not long after a battery replacements and it was a one off deal. Ive had them fail one after the other and new batteries solved the issue. Never heard of the GPCM causng that issue, tho I did have one I had to replace to get rid of the annoying CEL light it kept setting. Easy swap out, but you have to get it flashed to the truck at a dealer or someone with a TEC2 afterwards.

 

L5P glow plugs have a learn procedure that has to be done if one is replaced.. The glow plugs are controlled by the GPCM and the ECM.. We have replaced 2 engines for the tips breaking off when removing.. Remove them while the engine is still warm..

What is the learn proceedure, can

L5P glow plugs have a learn procedure that has to be done if one is replaced.. The glow plugs are controlled by the GPCM and the ECM.. We have replaced 2 engines for the tips breaking off when removing.. Remove them while the engine is still warm..

What is the learn procedure, can't find it anywhere??????

 

i have a 2018 Duramax. I got a glow plug 5 failure. i am going to trade the truck in in 5 days. will it be okay to drive it until them?

 

That one should be a pretty easy one to change out. It would clear the CEL and prevent any delays with the deal you made or will make. They will see it and likely reduce the trade-in value accordingly.

 

You can drive it, but with the CEL on the remote start won't work.