3.0 Duramax cranks but won’t start

Frankhpns · July 27, 2021

23 hours ago, ColoradoCub said:

I’d think twice before I allowed that type of repair to be done. There’s a ton of owners with tens of thousands of miles that have had many crank no starts with nothing wrong with the engines. And since this repair doesn’t fix the crank no start anyway, why do it? That truck will not be right when it’s put back together. Just asking for problems.

My logic is different than yours. There is something wrong with the engines, they have a defective bent part. GM is willing to extend warranty to cover potential unforeseen problems. I prefer to have mine fixed if it does not fix the problem I have several other options.

ColoradoCub · July 27, 2021

16 minutes ago, Frankhpns said:

My logic is different than yours. There is something wrong with the engines, they have a defective bent part. GM is willing to extend warranty to cover potential unforeseen problems. I prefer to have mine fixed if it does not fix the problem I have several other options.

You are free to do whatever you’d like with your truck, it’s yours. I’ve witnessed this kind of stuff too many times, but this resolution that GM has proposed for a not so serious driveability problem is the most insane thing I’ve seen yet. Completely ripping apart brand new trucks on a hunch that a bent exciter wheel is the culprit without proving their theory tops them all. I’m just advising other people if you like your truck and want to keep your truck, be very cautious about this situation. Not all mechanics are even capable of doing this repair without creating additional problems. There will be a fix at some point, but this is not it!

Frankhpns · July 27, 2021

38 minutes ago, ColoradoCub said:

You are free to do whatever you’d like with your truck, it’s yours. I’ve witnessed this kind of stuff too many times, but this resolution that GM has proposed for a not so serious driveability problem is the most insane thing I’ve seen yet. Completely ripping apart brand new trucks on a hunch that a bent exciter wheel is the culprit without proving their theory tops them all. I’m just advising other people if you like your truck and want to keep your truck, be very cautious about this situation. Not all mechanics are even capable of doing this repair without creating additional problems. There will be a fix at some point, but this is not it!

They did a diagnostic first then did a bore scope inspection without removing cab first. Once it was determined the reluctor was bent they initiated the repair.

tgivanoff · July 29, 2021

I also just experienced the issue of my 2021 silverado 3.0l duramax not starting. It currently has 12040 miles on it. I drove about 40 miles stopped at the grocery store for about 20 minutes and when I tried to start it the motor cranked but did not start. I repeated my attempt to start about 10 times with the same results. I also tried shifting to neutral and perform a start but all efforts failed. I then called the dealership for a tow. after the truck was dropped off at the dealers it started. no codes set so I got the call to "Come pick up my $55000 truck there is nothing wrong with your truck" answer. I went ballistic but kept my cool. then I googled the question 3.0 duramax won't start and here I am! Fortunately the dealership has another serviceman with common sense who stopped me from taking the truck till he has it checked out more than the no codes set issue.

Joe Brooks · July 29, 2021

I am quickly falling out of the exciter wheel causing it club. 12k miles. Seems that would have shown up way earlier. Sure seems like a software something makes more sense. May be proven wrong but if GM hasn’t got one of these trucks hooked to computer 24/7 and being driven daily we may never know the issue. Kinda wishing I would have bought that 2018 land cruiser with 80k on it for the same $$$$.

Edited July 29, 2021 by Joe Brooks

singlespeed · July 29, 2021

I agree, they are not even checking my exciter wheel until they fix the no start problem. The exciter wheel hasn't fixed anyone's no start truck that I know of. I tightened the fuse box bolts at 6k, have 11k on it and it hasn't done it again. So hopefully that fixed my truck. But who knows...

ColoradoCub · July 29, 2021

27 minutes ago, Joe Brooks said:

I am quickly falling out of the exciter wheel causing it club. 12k miles. Seems that would have shown up way earlier. Sure seems like a software something makes more sense. May be proven wrong but if GM hasn’t got one of these trucks hooked to computer 24/7 and being driven daily we may never know the issue. Kinda wishing I would have bought that 2018 land cruiser with 80k on it for the same $$$$.

Im right there with you. In addition I read another testimonial of a 3.0 owner that had his whole truck disassembled for the Reluctor wheel bulletin to fix the crank no start and it didn’t even take 6 days after he got it back and it did another crank no start while the Service manager was starting it! To make matters worse he has all kinds of things wrong with his truck post the repair and is now fighting with the dealership that did the work to fix it. That TSB is a nightmare in the making.

singlespeed · July 29, 2021

6 minutes ago, ColoradoCub said:

Im right there with you. In addition I read another testimonial of a 3.0 owner that had his whole truck disassembled for the Reluctor wheel bulletin to fix the crank no start and it didn’t even take 6 days after he got it back and it did another crank no start while the Service manager was starting it! To make matters worse he has all kinds of things wrong with his truck post the repair and is now fighting with the dealership that did the work to fix it. That TSB is a nightmare in the making.

100%

Joe Brooks · July 29, 2021

I just went and tightened the fuse panel bolts. The four inside the box correct? They weren’t loose but I could make few turns with a 1/4 drive ratchet. I don’t have an inch# torque wrench that goes real low so I just felt it out. Worth a shot.

GJR1212 · July 30, 2021

3 hours ago, Joe Brooks said:

I just went and tightened the fuse panel bolts. The four inside the box correct? They weren’t loose but I could make few turns with a 1/4 drive ratchet. I don’t have an inch# torque wrench that goes real low so I just felt it out. Worth a shot.

You can get a 1/4" drive, click type, torque wrench from Habor Freight. Seems like mine was $10 a few years ago. I first tightened mine after the one and only long crank event I've had. It took several rounds with the wrench to get to 40 in-lbs. Once at 40 I finished taking them to the spec of 53 in-lbs in several steps, like 42,45,48 ,51 then 53.

I noticed that my fuse box was marked with a white grease pencil checks at each of the four bolts. Most likely GM has a procedure for these bolts to be checked at final QC inspection.

After three weeks, I rechecked my fuse bolts and they where loose again, but nothing like the first time. They worked loose over heat cycles. The box is pretty close to that super hot exhaust reactor system which may explain why this problem seems to be more severe in the LM2 trucks than the gas trucks.

GM has a design problem with the fusebox IMHO. If you read this whole thread you will see that fixing bent timing wheels does not correct this problem, changing Engine control hardware and software, does nothing for this problem. Most cases do not throw any codes.

Edited July 30, 2021 by GJR1212
spelling

Joe Brooks · July 30, 2021

Was there a change in 21 to the fuse box and is the thought it is a grounding issue that may be the issue? Is that box grounded through those bolts?

moobaru · July 30, 2021

I had the crank no start on my '21 Sierra AT4 with the baby duramax in it at around 300 miles. I did some research and found the forum post linking to the bulletin about tightening down the fuse box bolts in the engine bay. I too had to turn them several rotations before they were in spec at 53 in-lb. I just turned over 5,000 miles today and I have not had the issue since I tightened down those bolts.

I have read a few posts (not sure if it is on this forum or another, where people claim to have the dealer check them and the dealer says they are fine. I'm curious if this is actually the fix and some dealers are not actually checking them when they say they are. It seems to me that the majority of people who find these bolts loose never have this issue again. But then again, it is very random and some people go several thousand miles between it happening. I'm wondering if I loosen the bolts a few turns if I can replicate this issue. Has anyone tried that?

ColoradoCub · July 30, 2021

I know guys want to believe that this problem is caused by A or B, but it’s much complex than that. Just hope they (GM) figure it out sooner than later.

GJR1212 · July 30, 2021

4 hours ago, Joe Brooks said:

Was there a change in 21 to the fuse box and is the thought it is a grounding issue that may be the issue? Is that box grounded through those bolts?

I was looking at some pictures of a 2020 Silverado fusebox on ebay. The four bolts appear to screw into the wiring plugs for each of the four quadrants of the fuse box. So when you torque the screws you are sandwitching together five layers of electrical connections with the relays and fuses on top, the sandwitch layer of curcuits and then the wire harness plugs on the bottom. The screws are completing ground circuits and also all the 12v supply and feed circuits as well.

Hamidar05 · July 31, 2021

On 3/23/2021 at 4:52 PM, Dbersuch said:

Bought a 2021 Sierra with the 3.0 last week. Twice when trying to start the truck the starter engages and cranks the engine but it will not fire. Starter times out after a few seconds and stops cranking. Anyone else have this happen? 570 miles on the truck.

Got my truck July 16. Crank no start has happened twice, both under 600 miles, guessing about 400 mi and 500 mi. I freaked out and started pushing the start button multiple times to try and get it to stop. Sounds like holding the button in will get the start cycle to stop? Once it stopped, waited and minute or so and it started fine. It's clear by sound there is no attempt for the engine to fire, it just cranks.

Sounds like no one is sure what it is at this point, especially GM? I hope the problem does not progressively get worse.