LB7 Cold Start Issues - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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  • 1 Post By M.A.M.
  • 1 Post By 77cruiser
 
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post #1 of 10 (permalink) Old 08-14-2019, 07:42 PM Thread Starter
 
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LB7 Cold Start Issues

Hey guys,

Long time lurker first time poster. 2003 LB7 hates the cold. Has to be plugged in to start. New ac delco glow plugs, new intake heater new glow plug controller. Will not start if its below 40. I love the truck but plugging it in is not always an option. About to pull my hair out. No the fuel is not gelled always run howes early october til late may. Balance rates show good oil never shows fuel. I took it to a shop around here and they broke a glow plug off so I paid them a $1000 and refuse to take my truck back. I got the glow plug out but the symptoms are the same. The shop swore up and down it was weak injectors but they will never see another truck I own. The options are limited up here as far as service. We also see 30 below in january and february. CALI EMISSIONS Thanks
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post #2 of 10 (permalink) Old 08-15-2019, 03:48 AM
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First thing I would do is hook it up to a computer and make sure the glow plugs are actually turning on when they are supposed to. Sounds like none of them are.


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9/26/17 80k miles with no issues...

--2015 GMC 3500 SRW/CCLB--

Engine rebuilt @ 170,000 miles due to hole in cylinder #7
First start on 5/13/16

8/29/17 REBUILD 2.0 @ 295k miles


255k miles on 4/1/17, and goin' strong...

S&B Intake, 3" MBRP downpipe, Flo-Pro 5" downpipe back exhaust/no muffler, PPEI tuned no longer, MOONSHINE tuned by Tony @ RidgeRunner, Airdog lift pump...

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Fingers Oval Bowl pistons @ 17.5:1 .040 over
Carrillo rods
chromoly pushrods
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ATI Super-Damper
ARP main and head studs
Keyed crank and cam
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305/55/20 MT Baja ATZ P3s on stock 20's...
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post #3 of 10 (permalink) Old 08-15-2019, 06:07 PM
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A simple, but not definitive, glow plug test is to watch the volt meter. After startup, voltage will drop substantially as the glow plugs light up and will stay low for a varying period until the controller backs them off and voltage rises into charge territory.

Itís 100F here in Carson City and frankly above 70, I donít even wait for my GP lamp to go out on a cold start. The engine starts instantly but I can still see the GPs cycle by watching the volt meter.

Well, let us know what you find out about the glow plugs and weíll go from there.

May I ask why you lurked so long before bringing up your question?

2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k
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post #4 of 10 (permalink) Old 08-15-2019, 06:08 PM Thread Starter
 
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the glow plugs come on they get hot guess it is not warm enough for the engine to start
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post #5 of 10 (permalink) Old 08-15-2019, 07:37 PM
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Glow plugs are digital in that they work or they donít and from your original post, you have replaced everything related to their operation, including the plugs.

Also, as I mentioned in my earlier post, above a certain temperature (maybe 50?) I donít believe they are essential for startup since the heat of compression is enough to ignite the fuel.

Most owners with starting issues have a problem opposite to yours which is related to the return circuit inside the injectors. When cold, the thicker diesel fuel is not particularly bothered by a sketchy return ball/seat, but on a hot start the thinner fuel bleeds past the defective ball/seat, causing rail pressure to be below the minimum required to ďwake upĒ the Fuel Injection Control Module.

Long crank times or no start is the result.

Since you seem sure your glow plugs are lighting up, I think the next thing to do is determine rail pressure during a cold crank. Why your system would do the opposite of most no-start, injector related situations is a mystery, but knowing rail pressure needs to be checked before proceeding with other tests.

There are apps available for use with an OBD2 transmitter ($25) and work on a smart phone (Android or iOS) that will tell you rail pressure and much more.

Or go to a reputable shop and have them run diagnostics. By the way, are you getting an MIL lamp? Codes?

That big chunk of change you dropped at the last place has got to hurt and I think many of us have been there.

Best

2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k
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post #6 of 10 (permalink) Old 08-16-2019, 07:10 AM Thread Starter
 
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This topic is beat to death. I feel like I am wasting your time as well as mine by bringing up another thread about it. In my area we have that shop and no others. They work on all the trucks at my job and we have never had an issue. They do great work or always have. So I trusted them. They mostly work on fords and you cannot make suggestions to the owner stubborn to say they least. Breaking a glow plug is about as stupid as it gets. They should know better. They tried to convince me the truck was on the way out bad injectors blah blah. Told me to sell or trade in. Ive been dealing with this for 2 winters. Almost ready to throw it in and move on to a gasser. I built a tiny house and use the truck to move it as I have no permanent location for it. I have a car so when its really cold i throw my hands up and drive the car. I love the truck just hate the cold. I have a code p0380 it comes and goes will stay off for days then pop back on. Glow plug light acts normal wont show up when hot then when its cold acts like its cycling.
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post #7 of 10 (permalink) Old 08-16-2019, 08:51 AM
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Have you checked the compression?
Mine started @ 0 F with no glow plugs working, although not very good.
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post #8 of 10 (permalink) Old 08-16-2019, 09:06 AM
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Nice!

Quote:
Originally Posted by 77cruiser View Post
Have you checked the compression?
Mine started @ 0 F with no glow plugs working, although not very good.
https://www.youtube.com/watch?v=JrfFQTHtix0
I think all the heat generated by your starter finally warmed thing up enough to fire the engine

Yep, compression is definitely the elephant in the room, and sounds like it is time to once again pull some glow plugs, get an adapter and do some testing.

Canít think of another option...

2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k
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post #9 of 10 (permalink) Old 08-16-2019, 09:11 AM
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Quote:
Originally Posted by stevewaclo View Post
I think all the heat generated by your starter finally warmed thing up enough to fire the engine
Maybe

04 GMC LB7 2500 SAC 45 injectors DSP5 EFI live from LDS, ported air inlet. 4" MBRP droning exhaust.
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post #10 of 10 (permalink) Old 08-18-2019, 05:37 PM Thread Starter
 
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Originally Posted by 77cruiser View Post
Maybe
sweet ill keep her cranking thanks for the help
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