Jump to content

Lbz Fuel Knock

Shawn T

By Shawn T
in Ask A GM Technician

Recommended Posts

Shawn T Enthusiast

Shawn T

Posted
Posted

Recently, I am getting a really loud knock out of my LBZ. Only 41000 miles and it only does it when it's cold. It sounds like a no-fuel in at least one cylinder. As soon as it warms up, it goes away. Not normal. Started about 3000 miles ago. Only prob, I've seen with the LBZ motor is a sticky EGR valve. I can pretty much rule this out, as it does not blow an ounce of smoke. Help is appreciated. Semi-plugged injector maybe? I need a diesel mechanics opinion. I posted this on the HD topic and not really getting a sure response. Do I take it in, or try some addative, and which brand? Please help.

gmtech4 Senior Enthusiast

gmtech4

Posted
Posted

Im pretty sure you have warranty ,take it in,they will run your vin and see ,,do not leave this condition to long ,over fuel means not a good ending for the pistons,

 

 

I saw a truck in northern BC that drove in with a bit of a miss ( more like a thump thump thump),after the head was removed ,there was no piston ,just a connecting rod making a rather large groove in the cyl wall,it was crazy

 

do not delay

Shawn T Enthusiast

Shawn T

Posted
  • Author
Posted
Im pretty sure you have warranty ,take it in,they will run your vin and see ,,do not leave this condition to long ,over fuel means not a good ending for the pistons,

 

 

I saw a truck in northern BC that drove in with a bit of a miss ( more like a thump thump thump),after the head was removed ,there was no piston ,just a connecting rod making a rather large groove in the cyl wall,it was crazy

 

do not delay

 

 

Ok, well I made an appointment for Monday and the service writer really had no clue what I was talking about, hopefully she is just a pencil pusher and has a good mechanic drive it and take a look. This better not be a "cannot duplicate" issue. That seems to be famous when it comes to Duramax issues. Thanks for the help.

gmtech4 Senior Enthusiast

gmtech4

Posted
Posted

the writer does just that ,writes the complaint and upsells crap,,for you not to get a "could not duplicate " you have to leave it overnight,and then they can duplicate it ,give lots of info ,speeds ,etc,

 

do not tell them what you think,they don't care,tell them the noise only etc.

 

good luck ,let us know

 

 

the scanner never lies lol

Shawn T Enthusiast

Shawn T

Posted
  • Author
Posted

Update: No codes, no low injector pressures. Everything checks out from top to bottom. The mechanic seemed knowledgable and honest. We took it for spin cold, and it knocked. After it hit about 100 degrees it started to quiet and then at 180 it quit all together. He definately heard the knock and acknowledged it's there. The fact of the matter is, it's just injector knock caused by a couple of things

 

1. Ultra Low Sulfur diesel is very dry and has 0 lubricating properties.

2. When LBZ's get watered-down fuel, it usually only takes once to make an injector noisy

 

He stated that with his experience that the LBZ's seem to be the most tempermental about water induced fuel and the Ultra Low Sulfer diesel is hell on these motors. He told me there is a line of the old 6.5 diesels with problems stemming from it.

 

I left it with him, he is going to add some additive and run it through. I think it's called Benzanine? Anyway, he said theres a 50/50 chance it will quiet it down. If it does not, he said he will gladly chase down the chattery injector but it's not a guarantee it will ever quiet down.

 

Have you seen this a lot lately too?

Nytemare Senior Enthusiast

Nytemare

Posted
Posted

Well its good that someone did hear it. Something to go back on if an injector or other stuff quits after the warranty is out.

 

Hopefully he can get it fixed, shitty to buy a new truck and have it knocking.

 

I dont know if an additive would help you out. Something like Lucas upper cylinder lube...or some kind of sulfur replacement/fuel conditioner.

minibike132 Senior Enthusiast

minibike132

Posted
Posted
Update: No codes, no low injector pressures. Everything checks out from top to bottom. The mechanic seemed knowledgable and honest. We took it for spin cold, and it knocked. After it hit about 100 degrees it started to quiet and then at 180 it quit all together. He definately heard the knock and acknowledged it's there. The fact of the matter is, it's just injector knock caused by a couple of things

 

1. Ultra Low Sulfur diesel is very dry and has 0 lubricating properties.

2. When LBZ's get watered-down fuel, it usually only takes once to make an injector noisy

 

He stated that with his experience that the LBZ's seem to be the most tempermental about water induced fuel and the Ultra Low Sulfer diesel is hell on these motors. He told me there is a line of the old 6.5 diesels with problems stemming from it.

 

I left it with him, he is going to add some additive and run it through. I think it's called Benzanine? Anyway, he said theres a 50/50 chance it will quiet it down. If it does not, he said he will gladly chase down the chattery injector but it's not a guarantee it will ever quiet down.

 

Have you seen this a lot lately too?

 

I've noticed it on mine when using ULSD and have had customers with the same complaint. I have never had anyone question the fact that the ULSD is causing it, it's easy enough to figure if you are someplace that still has both.

 

+1 on water, it only takes once. I have not used any since last winter so I have not checked to see if it will slow down the knock with ULSD but as far as keeping water out I think Howes Diesel additive is the best stuff on the market. I've never gelled and I have a few customers with their own tanks that do not have the best fuel. Once I put them on the stuff we cleared up all the fuel related issues except on a couple that were way too contaminated to deal with using only in tank conditioner.

 

Your guy is right, he could chase all day and still may never find it, I wouldn't worry about it if it was mine.

desrtrat Senior Enthusiast

desrtrat

Posted
Posted

I'm not up on the newer motors, but don't they have water/fuel separators on them? I'm use to older commercial truck that had them. what we did was check/drain any water from the separator every week, and when we did a fuel filter change instead of filling the filter with diesel fuel, we filler it with Lucas fuel injector cleaner. I'm wondering if changing the fuel filter and using Lucas would help.. some of our trucks had over 450k on them

 

good luck

 

:thumbs:

Shawn T Enthusiast

Shawn T

Posted
  • Author
Posted
Update: No codes, no low injector pressures. Everything checks out from top to bottom. The mechanic seemed knowledgable and honest. We took it for spin cold, and it knocked. After it hit about 100 degrees it started to quiet and then at 180 it quit all together. He definately heard the knock and acknowledged it's there. The fact of the matter is, it's just injector knock caused by a couple of things

 

1. Ultra Low Sulfur diesel is very dry and has 0 lubricating properties.

2. When LBZ's get watered-down fuel, it usually only takes once to make an injector noisy

 

He stated that with his experience that the LBZ's seem to be the most tempermental about water induced fuel and the Ultra Low Sulfer diesel is hell on these motors. He told me there is a line of the old 6.5 diesels with problems stemming from it.

 

I left it with him, he is going to add some additive and run it through. I think it's called Benzanine? Anyway, he said theres a 50/50 chance it will quiet it down. If it does not, he said he will gladly chase down the chattery injector but it's not a guarantee it will ever quiet down.

 

Have you seen this a lot lately too?

 

I've noticed it on mine when using ULSD and have had customers with the same complaint. I have never had anyone question the fact that the ULSD is causing it, it's easy enough to figure if you are someplace that still has both.

 

+1 on water, it only takes once. I have not used any since last winter so I have not checked to see if it will slow down the knock with ULSD but as far as keeping water out I think Howes Diesel additive is the best stuff on the market. I've never gelled and I have a few customers with their own tanks that do not have the best fuel. Once I put them on the stuff we cleared up all the fuel related issues except on a couple that were way too contaminated to deal with using only in tank conditioner.

 

Your guy is right, he could chase all day and still may never find it, I wouldn't worry about it if it was mine.

 

 

 

Thanks,

I have been searching for Howe's retailers on the net and I'm not getting anything but distributers. It doesn't look like any of the mayor parts stores carries it either. Where can I pick me some up?

minibike132 Senior Enthusiast

minibike132

Posted
Posted
Update: No codes, no low injector pressures. Everything checks out from top to bottom. The mechanic seemed knowledgable and honest. We took it for spin cold, and it knocked. After it hit about 100 degrees it started to quiet and then at 180 it quit all together. He definately heard the knock and acknowledged it's there. The fact of the matter is, it's just injector knock caused by a couple of things

 

1. Ultra Low Sulfur diesel is very dry and has 0 lubricating properties.

2. When LBZ's get watered-down fuel, it usually only takes once to make an injector noisy

 

He stated that with his experience that the LBZ's seem to be the most tempermental about water induced fuel and the Ultra Low Sulfer diesel is hell on these motors. He told me there is a line of the old 6.5 diesels with problems stemming from it.

 

I left it with him, he is going to add some additive and run it through. I think it's called Benzanine? Anyway, he said theres a 50/50 chance it will quiet it down. If it does not, he said he will gladly chase down the chattery injector but it's not a guarantee it will ever quiet down.

 

Have you seen this a lot lately too?

 

I've noticed it on mine when using ULSD and have had customers with the same complaint. I have never had anyone question the fact that the ULSD is causing it, it's easy enough to figure if you are someplace that still has both.

 

+1 on water, it only takes once. I have not used any since last winter so I have not checked to see if it will slow down the knock with ULSD but as far as keeping water out I think Howes Diesel additive is the best stuff on the market. I've never gelled and I have a few customers with their own tanks that do not have the best fuel. Once I put them on the stuff we cleared up all the fuel related issues except on a couple that were way too contaminated to deal with using only in tank conditioner.

 

Your guy is right, he could chase all day and still may never find it, I wouldn't worry about it if it was mine.

 

 

 

Thanks,

I have been searching for Howe's retailers on the net and I'm not getting anything but distributers. It doesn't look like any of the mayor parts stores carries it either. Where can I pick me some up?

 

 

I'm not sure where you are at, I get mine at Farm N Fleet here. Where are you located?

minibike132 Senior Enthusiast

minibike132

Posted
Posted
I'm not up on the newer motors, but don't they have water/fuel separators on them? I'm use to older commercial truck that had them. what we did was check/drain any water from the separator every week, and when we did a fuel filter change instead of filling the filter with diesel fuel, we filler it with Lucas fuel injector cleaner. I'm wondering if changing the fuel filter and using Lucas would help.. some of our trucks had over 450k on them

 

good luck

 

:thumbs:

 

 

Yes there is a seperator and idealy they would get drained often but no one does that.

Shawn T Enthusiast

Shawn T

Posted
  • Author
Posted
I'm not up on the newer motors, but don't they have water/fuel separators on them? I'm use to older commercial truck that had them. what we did was check/drain any water from the separator every week, and when we did a fuel filter change instead of filling the filter with diesel fuel, we filler it with Lucas fuel injector cleaner. I'm wondering if changing the fuel filter and using Lucas would help.. some of our trucks had over 450k on them

 

good luck

 

:dunno:

 

 

Yes there is a seperator and idealy they would get drained often but no one does that.

 

 

 

Located in Pueblo CO. Ag stores are Big R. Maybe there? I have been using the stanadyne the dealer gave me, after 2 tanks of it, I want to try the Howes

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • newdude
      Seems to be Missing a lot of Updates

      By newdude · Posted

      Based on what I can tell, yes.   As for updating it, its a mixed bag.  Updates do fix a lot of issues, but occasionally can create some oddities.  They do more good than harm though overall.     Here's what the most current one does and a  V171 Improvements Important: Improvements will vary by model, build configuration, system, and sales region. Not all vehicles have all features. OnStar and Wi-Fi may not work after remote start CarPlay may not automatically reconnect Part of the Driver Attention messaging screen may be in English even though the language is set to something else XM may not work After a dead 12V the radio may set to Arabic at each startup Bluetooth contacts might not be able to sync with the vehicle During an OTA the 12V battery may drain Customer might see a screen telling them to return to the dealer After changing the Wi-Fi SSID or password a device may not disconnect If a device is connected on the 2.4Ghz band, nothing will connect to the 5Ghz one, which could show as slow Wi-Fi speeds Customers might have noticed Wi-Fi dropping in certain areas and reconnecting later Customer might see the top of the screen blinking during Android Auto Android Auto may not connect CarPlay audio might momentarily cut out The "Add Phone" button may be grayed out The radio may not start up   V167 Most Notable Improvements:   Outside Air Temperature is incorrect. -You may see a popup message for Engine Shift. (Corvette Only) After changing the exhaust sound they get a popup that "mode change not applied", even though it was. -When changing volume, the volume bar is for Traffic instead of Audio. -(Corvette Only) Improvements to the placement of buttons and text. -If the customer receives the message "Apple CarPlay Could not connect", the cursor might move in the opposite direction than expected when using the control knob. -Android Auto automatically starts playing their music, even though they have turned that off in settings. -Intermittently they have a red OnStar LED with no OnStar function and/or no audio. -The minimum length of the Wi-Fi password was increased to 12 characters. -The popup message "Driver Attention Check, check your mirrors or Super Cruise will shut down" may not have come up on the display when it should have. -Startup animation added for 20th anniversary of the V-Series on Cadillacs. -The Navigation app received location improvements when going under long underpasses. -In the Navigation app there are filters for charging points that the vehicle cannot use.   V164 Most Notable Improvements Most notable improvements contained in this release may include: Apps Intermittently, an “SD Card Removed” message will pop up in the Navigation app. While in the audio app, the radio may stop working. Trailer Tire Pressure sensors may not be learned in the Trailer app. Not being able to return to the home screen while in the Camera app. After an ignition cycle, the radio might go to a black screen or stop working if using Sirius XM. Spotify icon truncated on Audio app.   SXM When changing power modes with the ignition switch, the HVAC pop up might appear. During startup, the radio will show the brand splash screen then go blank. Receiving a confirmation pop-up when changing drive modes. A “Return to Dealer” message may appear on the radio screen. SuperCruise setting toggle may not work. System After an ignition cycle, the radio might go black or stop working if using Sirius XM (SXM). Settings When performing a factory reset, the radio may stop working. After performing a factory reset, the radio may stop working when trying to switch users. When trying to go into the Language section quickly after startup, the radio may stop working. Projection Wireless CarPlay cannot be connected after unpairing another wireless Android Auto device. When the Android Auto screen comes up to connect wirelessly, the screen may freeze if the Cancel button is pressed. Removed the Apple CarPlay Cannot Connect screen when a device fails to pair during the autoconnect process. CarPlay information may not show up in the audio app. Near Field Communications (NFC) chime may be heard when NFC does not work. The Cannot Connect screen does not pop up after the first connection on wireless CarPlay fails. Apple CarPlay is now functional in Guam. Over the Air (OTA) When a software update is cancelled, the downloading logo may still be displayed. Energy When using the Energy app, the radio may stop working. When plugging in the vehicle, the display might show “Now” instead of “Charging Upon Plug In.” Instrument Cluster Voice recognition can be started while on an OnStar or phone call. When downloading contacts, there is a progress bar and circles on the Recents page of the cluster. The temperature on the cluster and the display may be different. After receiving and ending a call on the secondary paired phone, the cluster may get stuck on the phone menu. Bluetooth Intermittent Bluetooth connection loss.
    • AndrewF
      Front End Rattle

      By AndrewF · Posted

      Looking for help troubleshooting a metallic like front end rattle. Figured I’d see if anyone had thoughts before I schedule an appointment with the dealer.   The rattle is fairly loud and occurs primarily when the front driver side wheel hits a bump, even fairly minor road seams. Sometimes does it when the passenger hits a bump but I don’t believe when the rear hits. Rattle still occurs when foot is pressing brake peddle so I think that rules out the caliper rattle I’ve read about. I’ve also checked the running boards and they are tight.   Most noticeable at slow speeds.    Any insight is appreciated. 
    • KARNUT
      What did you do to your "other" car (aka musclecar) today

      By KARNUT · Posted

      We try to make cruise the coast. It’s where our favorite casino is. I only want to spectate. Never took a car. Always had one to take. I belonged to a club once. Even when I used to drag raced. It was during test and tune. Probably because I’m not a night owl, party person. 
    • RyanbabZ71
      What did you do to your "other" car (aka musclecar) today

      By RyanbabZ71 · Posted

      We had a pretty big cars and coffee in Indy this past weekend.  Pretty much anything and everything was there.  
    • Atlas
      What did you do to your "other" car (aka musclecar) today

      By Atlas · Posted

      Good looking Olds, and TRX!   I haven't been into car shows either. I'm probably not a convert but I did push myself this year to attend a few select events to challenge some assumptions and try to experience car-based social clubs in a different way. I joined up with the local Hagerty group for some cars/coffee events, group drives. A month ago I showed my '94 Camaro I rescued last fall at Radwood. Had a good time, but, there was some sitting around with the car and that's the part of shows I don't enjoy as much. I prefer to be a spectator, walk the show, grab a burger, go home.   Radwood was the only era-limited event, but where it had strict model year limitations, it made it up in variety. Having Jason Camissa there was also a hoot.   Where I see old 50's car shows, doo-wop and winga dinga music stuff fading out, same with "only" vintage muscle clubs, it seems to be the activity-based clubs/events which are gaining strong popularity. Places where all cars and interests come together.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...